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408 Cards in this Set
- Front
- Back
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Evolution
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is the process of change that has transformed life on earth
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Biology
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The scientific stufy of life
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The seven things about living organism
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order, regulation,energy processing,growth and development, reproductionevolutionary adaptation response to enviroment
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Biological organizations
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the biosphere, ecosystems,communities,populations,organisms,organs and organ systems,organelles tissues,cells,atoms,molecules
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biospehere?
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The planet
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ecosystem?
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the air and plants and animals
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Communities?
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interacting group of various species in a common location
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population
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A group of organisms of one species that interbreed and live in the same place at the same time (e.g. deer population).
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organism?
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The tree
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Organs and organ systems
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the leaves
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tissues
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stuff that makes up the leave
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emergent properties
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result from the arangement and interaction of parts within a system
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reductionism
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is the reduction of complex systems to simpler components that are more manageable to study
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Systems biology
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constructs models for the dynamic behavior of whole biological systems
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global warming is a major aspect of?
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global climate change
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the lowest level of organization that can perform all activities required for life
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cell
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all cells are enclosed by?
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a membrane
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cells use what as their genetic information?
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DNA
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Eukaryotic cell
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has a membrane enclosed organelles,the largest of which is usually the nucleus(DNA throughout)
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Prokayotic cell
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SImpler and usually smaller, and does not contain a nucleus or other membrane-encolsed organelles
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What contains most of a cells genetic material in the form of DNA?
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Chromosomes
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DNA is the substance of?
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genes
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what are the units of inheritance that transmit info from parents to offspring
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Genes
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DNA controls the ?
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Development and maintenance of orgnaisms
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Each DNA molecule is made up of two long chains arranged in a?
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double helix
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each link of a chain is one of four kinds of chemical building blocks called?
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Nucleotides
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nucleotides are nicknamed?
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A,G,C, and T
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DNA is inside the ?
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nucleus
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genes control what indirectly?
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protein production
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DNA is transcribed into what??
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RNA
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after DNA is transcribed it is then translated into a?
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Protein
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Gene expression
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is the process of converting information from gene to cellular product
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Genome
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is its enitre set of genetic instructions
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genomic is the study of?
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sets of genes within and between species
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bioinformatics
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is the use of computational tools to process a large volume of data
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feedback mechanisms allow biological processes to?
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self regulate
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Negative Feedback
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means that as more of a product accumulates,the process that creates it slows and less of the product is produced
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Positive feedback
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means that as more of a product accumulate the process that creates it speeds up and more of the product is produced
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Taxonomy
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is the branch of biology that names and classifies species into groups of increasing breath
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Domains followed by kingdoms are the what units of classification?
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broadest
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taxonomy levels in order from biggest to smallest
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Domain,kingdom,phylum,class,order,family,genus,species
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names of the groups in taxonomy levels biggest to smallest taxonomy levels
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Eukarya,animalia,chordata,mammalla,carnivora,uraldae,ursus,ursus americanus
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organisms are divided into three domains
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Bacteria and archaea-compose the prokaryotes ,eukarya
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domain eukarya
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includes all eukaryotic organisms
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Eukarya includes three multicellular kingdoms
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Plants-photosynthesis, fungi- absorb nutrients, and animals which ingest their food
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DNA is the universal genetic what ?
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language to all organism
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Charles Darwin published
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On the origin of species by means of natural selection
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In darwins book species showed evidence of ?
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descent with modification from common anncestors (natural selection)
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darwin said more offspring are what?
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produced than survived and competition is inevitable
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science is derived from latin means?
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to know
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Inquiry
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is the search for info and explanation
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scientific process includes?
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making observations,forming logical hypotheses,and testing them
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Data
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are recorded observations or items of info.
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Qualitatic
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descriptions
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quantitative
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or recorded measurements
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inductive reasoning
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draws conclusions through the logical process of induction
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hypothesis
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is a tentative answer to a well framed question
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deductive reasoning
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uses genereal premises to make specific predictions
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controlled experiment
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compares and experimental group with a control group
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theory is ?
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broader in scope than a hypothesis, can lead to new testable hypotheses, supported by a large body of evidence in comparison to a hypothesis
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matter
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anything that takes ip space and has mass
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element
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a substance that cannot be broken down to other substances by chemical reactions
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compound
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a substance consisting of two or more elements in a fixed ratio
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carbon hydrogen oxygen and nitrogen make up ?
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96 percent of living matter
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most of the remaining 4 percent of whats in living matter?
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calcium,phosphorus,potassium,and sulfur
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trace elements
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are those required by and organism in minute quantities
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atom is the?
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smallest unit of matter that still retains the properties of and element
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atoms are composed of subatomic particles
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Neutrons,Protons, Electrons
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neutrons and protons form what nucleus?
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atomic nucleus
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Electrons form a ?
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Cloud around the nucleus
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neutrons and protons mass are almost identical and are measured in ?
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daltons
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atomic number
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is the number of protons in a nucleus
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mass number
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is the sum of protons and neutrons in the nucleus
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atomic mass
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the atoms total mass,can be approximated by the mass number
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all atoms of an element have the same # of? but differ in?
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protons neutrons
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Isotopes
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two atoms of an element that differ in the number of neutrons
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radioactive isotopes
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decay spontaneously,giving off particles and energy
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radioactive isotopes in bio research?
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Dating fossils,tracing atoms through metabolic processes,diagnosing medical disorders
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energy
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the capacity to cause change
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potential energy
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is the energy that matter has because of its location or structure
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an electrons state of potential energy is called
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energy level or electron shell
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the chemical behavior of an atom is determined by?
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the distribution of electrons in electron shells
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valence electrons
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are those in the outermost shell or valence shell
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chemical behavior of an atom is mostly determined by
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valence electrons
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elements with a full valence shell are?
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Chemically inert
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orbital
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the three dimensional space where and electron is found 90% of the time
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atoms staying close together held by attractions?
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chemical bonds
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covalent bond
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is the sharing of a pair of valence electrons by two atoms
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molecule
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consists of two or more atoms held together by covalent bonds
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single bond
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is the sharing of one pair of valence electrons
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Double bond
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is the sharing of two pairs of valence electrons
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structural formula
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represents atoms and bonding
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molecular formula
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abbreviates the structural formula
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compound
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combination of two or more DIFFERENT elements
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Bonding capacity is called the atoms?
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valence
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Electronegativity
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is an atom’s attraction for the electrons in a covalent bond
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nonpolar covalent bond
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the atoms share the electron equally
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polar covalent bond
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one atom is more electronegative, and the atoms do not share the electron equally
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ion
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a charged atom (or molecule)
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cation
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is a positively charged ion
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anion
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is a negatively charged ion
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ionic bond
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attraction between and anion and cation
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compounds formed by ionic bonds are called
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ionic compounds,or salts
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covalent bonds are the strongest bond in an organism they form a cells?
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molecules
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weak chemical bonds are important because?
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weak chemical bonds reinforce shapes of large molecules and help molecules adhere to each other
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hydrogen bonds
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forms when a hydrogen atom covalently bonded to one electronegatice atom is also attracted to another electronegative atom
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In living cells, the electronegative partners are usually
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oxygen or nitrogen atoms
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hot spots are?
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electrons are distributed asymmetrically in molecules or atoms
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Van der waals interactions
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are attractions between molecules that are close together as a result of these charges
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molecules with similar shapes can have similar
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biological effects
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Chemical reactions
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are the making and breaking of chemical bonds
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Reactants
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The starting molecules of a chemical reaction are called
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products
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The final molecules of a chemical reaction are called
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Photosynthesis
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Sunlight powers the conversion of carbon dioxide and water to glucose and oxygen
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Chemical equilibrium
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is reached when the forward and reverse reaction rates are equal
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water molecule
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polar molecule
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polarity allows water molecules to form
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hydrogen bonds with eachother
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Four of water’s properties that facilitate an environment for life are
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Cohesive behavior Ability to moderate temperature Expansion upon freezing Versatility as a solvent
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cohesion
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Collectively, hydrogen bonds hold water molecules together,
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adhesion
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is an attraction between different substances, for example, between water and plant cell walls
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surface tension
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is a measure of how hard it is to break the surface of a liquid
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Kinetic energy
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energy of motion
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heat
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measure of the total amount of kinetic energy due to molecular motion
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temperature
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measures the intensity of heat due to the average kinetic energy of molecules
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calorie (cal)
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is the amount of heat required to raise the temperature of 1 g of water by 1°C
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kilocalories (kcal)
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1kcal=1000 cal
actually the calories on food packages |
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Joules
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unit of energy where 1j=.239 cal or 1cal =4.184j
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specific heat
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heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1ºC
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heat is absorbed when hydrogen bonds? an it is released?
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break, form
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Heat of vaporization
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is the heat a liquid must absorb for 1 g to be converted to gas
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evaporatice cooling
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As a liquid evaporates, its remaining surface cools
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hydrogen bonds in ice are more ordered making it?
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float
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at 4 degrees celcius
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water reaches its greatest density
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solution
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is a liquid that is a homogeneous mixture of substances
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solvent
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dissolving agent of a solution
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solute
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is the substance that is dissolved
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aqueous solution
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one in which water is the solvent
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When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a
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hydration shell
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water can also dissolve compounds made of
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nonionic polar molecules
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hydrophilic
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substance is one that has an affinity for water
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hydrophobic
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substance is one that does not have an affinity for water
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colloid
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is a stable suspension of fine particles in a liquid
© 2011 |
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Molecular mass
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is the sum of all masses of all atoms in a molecule
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number of molecules are usually measured in ?
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moles
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1mole(mol)=
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6.02 x 10^23 molecules
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1g=
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6.02x10^23 daltons
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Molarity
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is the number of moles of solute per liter of solution
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hydrogen ion (H+)
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The hydrogen atom leaves its electron behind and is transferred as a proton,
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hydronium ion(H3O)
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The molecule with the extra proton
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hydroxide ion (OH–)
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The molecule that lost the proton
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acid
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is any substance that increases the H+ concentration of a solution
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base
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is any substance that reduces the H+ concentration of a solution
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acidic solutions have pH values
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less than 7
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basic solutions have a pH value
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greater than 7
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biological fluids pH
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range from 6 to 8
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Buffers
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are substances that minimize changes in concentrations of H+ and OH– in a solution
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ocean acidification
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CO2 dissolved in sea water forms carbonic acid; this process is called
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Acid precipitation
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is rain, fog, or snow with a pH lower than 5.2
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living organisms consist mostly of
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carbon-based compounds
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Organic chemistry
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is the study of compounds that contain carbon
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Vitalism
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the idea that organic compounds arise only in organisms, was disproved when chemists synthesized these compounds
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Mechanism
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is the view that all natural phenomena are governed by physical and chemical laws
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Electron configuration is the key to an atom’s
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characteristics
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carbon chains form the skeletons of
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most organic molecules
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Hydrocarbons
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are organic molecules consisting of only carbon and hydrogen
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Isomers
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are compounds with the same molecular formula but different structures and properties
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Structural isomers
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have different covalent arrangements of their atoms
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Cis-trans isomers (Geometric)
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have the same covalent bonds but differ in spatial arrangements
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Enantiomers
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are isomers that are mirror images of each other
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Functional groups
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are the components of organic molecules that are most commonly involved in chemical reactions
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arrangement of functional groups
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give each molecule its unique properties
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the seven functional groups are?
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Hydroxyl,carbonyl,carboxyl,amino,sulfydryl,phospate,methyl
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hydroxyl
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has an -OH
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carbonyl
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c=o
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carboxyl
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OH-c=O
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amino
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h-n-h
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sulfhydryl
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-SH
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phosphate
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p double bonds to an O and single bong to one O+ and two O-
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methyl
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C:H3
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adenosine triphosphate (ATP)
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is the primary energy-transferring molecule in the cell
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ATP consists of an organic molecule called?
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adenosine attached to a string of three phosphate groups
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All living things are made up of four classes of large biological molecules:
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carbohydrates, lipids, proteins, and nucleic acids
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Macromolecules
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are large molecules composed of thousands of covalently connected atoms
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polymer
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is a long molecule consisting of many similar building blocks
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These small building-block molecules are called
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monomers
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Three of the four classes of life’s organic molecules are polymers
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carbohydrates,proteins,nucleic acids
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dehydration reaction
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occurs when two monomers bond together through the loss of a water molecule
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Polymers are disassembled to monomers by
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hydrolysis
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hydrolysis
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a reaction that is essentially the reverse of the dehydration reaction
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Carbohydrates
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include sugars and the polymers of sugars
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monosaccharides are the simplest carbohydrates or
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single sugars
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Carbohydrate macromolecules are
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polysaccharides
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polysaccharides
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polymers composed of many sugar building blocks
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Monosaccharides
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have molecular formulas that are usually multiples of CH2O
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glucose most common?
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monosaccharide
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Monosaccharides are classified by
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The location of the carbonyl group (as aldose or ketose) and the number of carbons in the carbon skeleton
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disaccharide
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is formed when a dehydration reaction joins two monosaccharides( glycosidic linkage)
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Polysaccharides
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the polymers of sugars, have storage and structural roles
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Starch
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a storage polysaccharide of plants, consists entirely of glucose monomers
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Plants store surplus starch as granules within
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within chloroplastds and other plastids
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simplest form of starch is
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amylose
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starch
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plant polysaccaride
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glycogen
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an animal polysaccharide
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cellulose (polysac)
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is a major component of the tough wall of plant cells (polymer of glucose)
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Polymers with α glucose are
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helical
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Polymers with β glucose
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are straight
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Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for
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plants
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Enzymes that digest starch by hydrolyzing α linkages can’t hydrolyze β linkages in
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cellulose
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Some microbes use enzymes to
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to digest cellulose
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Chitin
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another structural polysaccharide, is found in the exoskeleton of arthropods, (also provides structural support for the cell walls of many fungi)
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Lipids
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are the one class of large biological molecules that do not form polymers
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lipids are?
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hydrophobic ( contain hydrocarbons, which form nonpolar covalent bonds)
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most biologically impt lipids ?
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fats,phospholipids,and steroids
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Fats
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are constructed from two types of smaller molecules: glycerol and fatty acids
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Glycerol is a
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three-carbon alcohol with a hydroxyl group attached to each carbon
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fatty acid
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consists of a carboxyl group attached to a long carbon skeleton
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Fats separate from water because
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water molecules form hydrogen bonds with each other and exclude the fats
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triacylglycerol
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In a fat, three fatty acids are joined to glycerol by an ester linkage,
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Saturated fatty acids
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have the maximum number of hydrogen atoms possible and no double bonds
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Unsaturated fatty acids
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have one or more double bonds
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saturated fats are?
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solid at room temp
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most animal fats are?
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saturated
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unsaturated
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liquid at room temp
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plants fats and fish fats are usually?
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unsaturated
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Hydrogenation
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is the process of converting unsaturated fats to saturated fats by adding hydrogen
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Hydrogenating vegetable oils also creates unsaturated fats with
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trans double bonds
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Humans and other mammals store their fat in
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adipose cells
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Adipose tissues?
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cushions vital organs and insulates the body
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phospholipid
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two fatty acids and a phosphate group are attached to glycerol
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Steroids
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are lipids characterized by a carbon skeleton consisting of four fused rings
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Cholesterol
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an important steroid, is a component in animal cell membranes
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Proteins account for more than 50% of the
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dry mass of most cells
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Protein functions include
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structural support, storage, transport, cellular communications, movement, and defense against foreign substances
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Enzymatic proteins
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Selective acceleration of chemical reactions
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Storage proteins
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Storage of amino acids
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Hormonal proteins
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Coordination of an organism’s activities
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Contractile and motor proteins
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Movement
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Defensive proteins
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Protection against disease
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Transport proteins
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Transport of substances
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Receptor proteins
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Response of cell to chemical stimuli
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Structural proteins
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Support
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Polypeptides
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are unbranched polymers built from the same set of 20 amino acids
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protein
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is a biologically functional molecule that consists of one or more polypeptides
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Amino acids
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are organic molecules with carboxyl and amino groups
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Amino acids differ in their properties due to differing side chains called?
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R groups
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Amino acids are linked by
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peptide bonds
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polypeptide is a polymer of
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amino acids
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A functional protein consists of one or more polypeptides precisely
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twisted, folded, and coiled into a unique shape
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The sequence of amino acids determines a protein’s
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three dimensional structure (primary structure)
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protein’s structure determines
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its function
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Secondary structure,
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found in most proteins, consists of coils and folds in the polypeptide chain
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Tertiary structure
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is determined by interactions among various side chains (R groups:These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions)
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Quaternary structure
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results when a protein consists of multiple polypeptide chains
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Primary structure
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is determined by inherited genetic information
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The coils and folds of secondary structure result from
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hydrogen bonds between repeating constituents of the polypeptide backbone
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Typical secondary structures are a coil called
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an α helix and a folded structure called a β pleated sheet
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may reinforce the protein’s structure (strong covalent bonds)
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disulfide bridges
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Quaternary structure
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results when two or more polypeptide chains form one macromolecule
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Collagen is
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a fibrous protein consisting of three polypeptides coiled like a rope
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Hemoglobin
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is a globular protein consisting of four polypeptides: two alpha and two beta chains
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Sickle-cell disease
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an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin
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Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein
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to unravel
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This loss of a protein’s native structure is called
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denaturation (biologically inactive)
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Chaperonins
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protein molecules that assist the proper folding of other proteins
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X-ray crystallography
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determine a protein’s structure
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Another method to determine a proteins structure is nuclear magnetic resonance (NMR) spectroscopy which does not require?
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protein crystallization
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Bioinformatics
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uses computer programs to predict protein structure from amino acid sequences
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The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a
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gene
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Genes are made of DNA, a
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nucleic acid made of monomers called nucleotides
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two types of nucleic acids
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Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA |
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DNA provides directions for its own
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replication
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DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls
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protein synthesis
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protein synthesis occurs on
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ribosomes
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Nucleic acids are polymers called
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polynucleotides
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Each polynucleotide is made of monomers called
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nucleotides
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Each nucleotide consists of
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a nitrogenous base, a pentose sugar, and one or more phosphate groups
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The portion of a nucleotide without the phosphate group is called
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a nucleoside
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Nucleoside =
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nitrogenous base + sugar
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There are two families of nitrogenous bases
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Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring
Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring |
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In DNA, the sugar is
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deoxyribose
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in RNA, the sugar is
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ribose
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Nucleotide =
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nucleoside + phosphate group
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Nucleotide polymers are linked together to build
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polynucleotide
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The sequence of bases along a DNA or mRNA polymer is
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unique for each gene
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RNA molecules usually exist as
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single polypeptide chains
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DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a
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double helix
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In the DNA double helix, the two backbones run in opposite 5′→ 3′ directions from each other, an arrangement referred to as
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antiparallel
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The nitrogenous bases in DNA pair up and form hydrogen bonds:
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adenine (A) always with thymine (T), and guanine (G) always with cytosine (C)
(COMPLIMENTARY BASE PAIRING) |
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Complementary pairing can also occur between
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two RNA molecules or between parts of the same molecule
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In RNA, thymine is replaced by
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uracil (U) so A and U pair
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The cell is the
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simplest collection of matter that can be alive
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Cell structure is correlated to
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cellular function
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All cells are related by their descent from
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earlier cells
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light microscope (LM),
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visible light is passed through a specimen and then through glass lenses
(lenses refract (bend) the light, so that the image is magnified) |
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Three important parameters of microscopy
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magnification,resolution,contrast
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LMs can magnify effectively to about
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1,000 times the size of the actual specimen
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Most subcellular structures, including organelles (membrane-enclosed compartments), are
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too small to be resolved by an LM
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Two basic types of electron microscopes (EMs) are used to study
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subcellular structures
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Scanning electron microscopes (SEMs)
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focus a beam of electrons onto the surface of a specimen, providing images that look 3-D
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Transmission electron microscopes (TEMs)
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focus a beam of electrons through a specimen,TEMs are used mainly to study the internal structure of cells
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Recent advances in light microscopy
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Confocal microscopy and deconvolution microscopy provide sharper images of three-dimensional tissues and cells
– New techniques for labeling cells improve resolution |
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Cell fractionation
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takes cells apart and separates the major organelles from one another
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Centrifuges fractionate cells into
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their component parts
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Cell fractionation enables scientists to determine
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Cell fractionation enables scientists to determine
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Biochemistry and cytology help correlate cell function
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with structure
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The basic structural and functional unit of every organism is one of two types of cells:
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prokaryotic and eukaryotic
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Basic features of all cells
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Plasma membrane
– Semifluid substance called cytosol – Chromosomes (carry genes) – Ribosomes (make proteins) |
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Prokaryotic cells are characterized by having
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No nucleus – DNA in an unbound region called the nucleoid – No membrane-bound organelles – Cytoplasm bound by the plasma membrane |
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Eukaryotic cells are characterized by having
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DNA in a nucleus that is bounded by a membranous nuclear envelope – Membrane-bound organelles – Cytoplasm in the region between the plasma membrane and nucleus |
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plasma membrane
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is a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
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The general structure of a biological membrane is a
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double layer of phospholipids
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Metabolic requirements set upper limits on
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size of the cell
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As the surface area increases by a factor of ..., the volume increases by a factor of...
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n^2, n^3
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Small cells have a greater surface area relative
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to volume
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A eukaryotic cell has internal membranes that partition the cell into
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organelles
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Plant and animal cells have most of the same
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organelles
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The nucleus contains most of the
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DNA in a eukaryotic cell
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Ribosomes use the information from the DNA to
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make proteins
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The nucleus
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contains most of the cell’s genes and is usually the most conspicuous organelle
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The nuclear envelope
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encloses the nucleus, separating it from the cytoplasm
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The nuclear membrane is a,
Each membrane consists of a |
double membrane
lipud bilayer |
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Pores
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regulate the entry and exit of molecules from the nucleus
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nuclear lamina
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The shape of the nucleus is maintained by the
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chromosomes
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In the nucleus, DNA is organized into discrete units called
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nuclear lamina
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which is composed of protein
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The DNA and proteins of chromosomes are together called
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chromatin
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chromatin condenses to form discrete.... as a cell prepares to divide
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chromosomes
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the nucleolus is located within
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the nucleus and is the site of ribosomal RNA (rRNA) synthesis
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Ribosomes
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are particles made of ribosomal RNA and protein
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Ribosomes carry out protein synthesis in two locations
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In the cytosol (free ribosomes) – On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes) |
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Components of the endomembrane system
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Nuclear envelope – Endoplasmic reticulum – Golgi apparatus – Lysosomes – Vacuoles – Plasma membrane |
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These components are either continuous or connected via transfer by
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vesicles
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The endoplasmic reticulum (ER)
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accounts for more than half of the total membrane in many eukaryotic cells
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The ER membrane is continuous with the
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nuclear envelope
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there are two distinct regions of ER what are they?
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Smooth ER, which lacks ribosomes
– Rough ER, surface is studded with ribosomes |
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The smooth ER does?
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Synthesizes lipids – Metabolizes carbohydrates – Detoxifies drugs and poisons – Stores calcium ions |
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The rough ER does?
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Has bound ribosomes, which secrete glycoproteins (proteins covalently bonded to carbohydrates)
– Distributes transport vesicles, proteins surrounded by membranes – Is a membrane factory for the cell |
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The Golgi apparatus
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consists of flattened membranous sacs called cisternae
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functions of the golgi apparatus?
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Modifies products of the ER – Manufactures certain macromolecules – Sorts and packages materials into transport vesicles |
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A lysosome
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is a membranous sac of hydrolytic enzymes that can digest macromolecules
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Lysosomal enzymes can hydrolyze
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proteins, fats, polysaccharides, and nucleic acids
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Lysosomal enzymes work best in
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the acidic environment inside the lysosome
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Some types of cell can engulf another cell by
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phagocytosis (forms a food vacuole)
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A lysosome fuses with the food vacuole and?
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digests the molecules
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Lysosomes also use enzymes to recycle the cell’s own
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organelles and macromolecules, a process called autophagy
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A plant cell or fungal cell may have one or several? derived from what?
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vacuoles
endoplasmic reticulum and Golgi apparatus |
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Food vacuoles
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are formed by phagocytosis
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Contractile vacuoles
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found in many freshwater protists, pump excess water out of cells
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Central vacuoles,
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found in many mature plant cells, hold organic compounds and water
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The endomembrane system is a complex and dynamic player in the cell’s
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compartmental organization
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Mitochondria
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are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP
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Chloroplasts,
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found in plants and algae, are the sites of photosynthesis
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Peroxisomes are
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oxidative organelles
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Mitochondria and chloroplasts have similarities with bacteria
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Enveloped by a double membrane – Contain free ribosomes and circular DNA molecules – Grow and reproduce somewhat independently in cells |
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Mitochondria are in nearly all
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eukaryotic cells
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(mitochondria) They have a smooth outer membrane and an inner membrane folded into
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cristae
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(mitochondria) The inner membrane creates two compartments: intermembrane space and
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mitochondrial matrix
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Some metabolic steps of cellular respiration are
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catalyzed in the mitochondrial matrix
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Cristae present a large surface area for
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enzymes that synthesize ATP
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Chloroplasts contain the green pigment called?
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chlorophyll, as well as enzymes and other molecules that function in photosynthesis
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Chloroplast structure includes
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Thylakoids, membranous sacs, stacked to form a granum
– Stroma, the internal fluid |
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The chloroplast is one of a group of plant organelles, called
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plastids
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Peroxisomes
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are specialized metabolic compartments bounded by a single membrane
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Peroxisomes produce hydrogen peroxide and convert it
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to water
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The cytoskeleton
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is a network of fibers extending throughout the cytoplasm
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cytoskeleton
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It organizes the cell’s structures and activities, anchoring many organelles
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cytoskeletons is composed of three types of molecular structures
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Microtubules – Microfilaments – Intermediate filaments |
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The cytoskeleton helps to
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support the cell and maintain its shape
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cytoskeleton interacts with?
to produce? |
motor proteins
motility |
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Inside the cell, vesicles can travel along
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monorails provided by the cytoskeleton
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Microtubules
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are hollow rods about 25 nm in diameter and about 200 nm to 25 microns long
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Functions of microtubules
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Shaping the cell – Guiding movement of organelles – Separating chromosomes during cell division |
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In many cells, microtubules grow out from a
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centrosome
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The centrosome is a?
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"microtubule-organizing center"
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In animal cells, the centrosome has a pair of?
each with nine triplets of ? |
centrioles
microtubules arranged in a ring |
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Microtubules control the beating of?
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cilia and flagella, locomotor appendages of some cells
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Cilia and flagella differ
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differ in their beating patterns
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Cilia and flagella share a common structure
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A core of microtubules sheathed by the plasma membrane – A basal body – A motor protein called dynein |
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basal body
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that anchors the cilium or flagellum
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dynein
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which drives the bending movements of a cilium or flagellum
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Microfilaments
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are solid rods about 7 nm in diameter, built as a twisted double chain of actin subunits
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The structural role of microfilaments
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is to bear tension, resisting pulling forces within the cell
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microfilaments They form a 3-D network called the
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cortex just inside the plasma membrane to help support the cell’s shape
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Bundles of microfilaments make up the core of
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microvilli of intestinal cells
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Microfilaments that function in cellular motility contain the protein
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myosin in addition to actin
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In muscle cells, thousands of actin filaments
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are arranged parallel to one another
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Pseudopodia
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(cellular extensions) extend and contract through the reversible assembly and contraction of actin subunits into microfilaments
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Cytoplasmic streaming
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is a circular flow of cytoplasm within cells
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In plant cells, actin-myosin interactions and sol-gel transformations drive
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cytoplasmic streaming
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Intermediate filaments
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range in diameter from 8–12 nanometers, larger than microfilaments but smaller than microtubules, they support cell shape and fix organelles in place.
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Most cells synthesize and secrete materials that are external to
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the plasma membrane
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These extracellular structures include
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Cell walls of plants – The extracellular matrix (ECM) of animal cells – Intercellular junctions |
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The cell wall
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is an extracellular structure that distinguishes plant cells from animal cells
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Prokaryotes, fungi, and some protists also have
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cell walls
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Plant cell walls are made of
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cellulose fibers embedded in other polysaccharides and protein
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Plant cell walls may have multiple layers
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Primary cell wall: relatively thin and flexible – Middle lamella: thin layer between primary walls of adjacent cells – Secondary cell wall (in some cells): added between the plasma membrane and the primary cell wall |
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Plasmodesmata are
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channels between adjacent plant cells
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Animal cells lack cell walls but are covered by an elaborate
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extracellular matrix (ECM)
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The ECM is made up of glycoproteins such as
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collagen, proteoglycans, and fibronectin
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ECM proteins bind to receptor proteins in the plasma membrane called
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integrins
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Functions of the ECM?
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Support – Adhesion – Movement – Regulation |
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Intercellular junctions
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they help facilitate this contact (neighboring cells in tissues, organs, or organ systems interact)
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There are several types of intercellular junctions
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Plasmodesmata – Tight junctions – Desmosomes – Gap junctions |
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Plasmodesmata
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are channels that perforate plant cells walls
(water and small solutes can pass from cell to cell) |
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tight junctions
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membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
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Desmosomes
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(anchoring junctions)fasten cells together into strong sheets
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Gap junctions
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(communicating junctions) provide cytoplasmic channels between adjacent cells
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Cells rely on the integration of
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structures and organelles in order to functon
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