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135 Cards in this Set
- Front
- Back
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Acid |
A substance that increases the hydrogen ion concentration of a solution |
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Adhesion |
The clinging of one substance to another, such as water to plant cell walls, by means of hydrogen bonds |
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Base |
a substance that reduces the hydrogen ion concentration of a solution |
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Bond |
Weak attractions between two molecules (or two regions of a large molecule) with polar covalent bonds
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Buffer |
A solution that contains a weak acid and its corresponding base. A buffer minimizes changes in pH when acids or bases are added to the solution.
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Cohesion |
The linking together of like molecules, often by hydrogen bonds.
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Heat of vaporization |
The quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state.
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Hydrophilic |
Having an affinity (An attraction or force between particles that causes them to combine) for water
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Hydrophobic |
Having no affinity for water; tending to coalesce and form droplets in water.
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pH |
A measure of hydrogen ion concentration equal to –log [H1] and ranging in value from 0 to 14.
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Polar |
A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive
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Non Polar |
A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.
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Salt |
a substance that dissolves into ions in water
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Solute |
the dissolved substances
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Solution |
solutes PLUS the liquid solvent
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Solvent |
a chemical medium capable of causing some substances to dissolve within it
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Surface Tension |
The attractive force exerted upon the surface molecules of a liquid by the molecules beneath that tends to draw the surface molecules into the bulk of the liquid and makes the liquid assume the shape having the least surface area
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Anion |
a negatively charged ion |
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Atomic number |
The number of protons in the nucleus of an atom, unique for each element and designated by a subscript
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Atomic Weight |
average mass number in a sample, due to the variation in number of neutrons
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Covalent Bond |
A type of strong chemical bond in which two atoms share one or more pairs of valence electrons
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Ionic Bond |
A chemical bond resulting from the attraction between oppositely charged ions
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Hydrogen Bond |
A type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule.
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Cation |
positively charged ion |
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Electron |
A subatomic particle with a single negative electrical charge and a mass about 1/2,000 that of a neutron or proton. One or more electrons move around the nucleus of an atom
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Electronegative |
Relating to or charged with negative electricity
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Element |
Any substance that cannot be broken down to any other substance by chemical reactions
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Ion |
An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge
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Isotope |
One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass.
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Macromolecule |
A giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction. Polysaccharides, proteins, and nucleic acids are macromolecules
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Mass Number |
The total number of protons and neutrons in an atom’s nucleus
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Molecule |
Two or more atoms held together by covalent bonds
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Molecular Formula |
tell us the elementsand numberof atomsin a molecule
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Neutron |
A subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7 3 10224 g, found in the nucleus of an atom.
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Nucleus |
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin. (3) A cluster of neurons.
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Orbital |
represents a different energy level
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Proton |
(1) Mass Number = 1 (2) positive electrical charge (3) defines the chemical element; never lost or gained |
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Valence Electron |
An electron in one of the outer shells of an atom that can participate in forming chemical bonds with other atoms
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Valence Shell |
the outermost shell of an atom containing the valence electrons
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Biosphere |
The entire portion of Earth inhabited by life; the sum of all the planet’s ecosystems.
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Cell |
The basic structural, functional, and biological unit of all known living organisms
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Consumer |
organisms of an ecological food chain which receive energy by consuming other organisms
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DNA |
A nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell’s proteins
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Domain |
(1) A taxonomic category above the kingdom level. The three domains are Archaea, Bacteria, and Eukarya. (2) A discrete structural and functional region of a protein.
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Ecosystem |
All the organisms in a given area as well as the abiotic factors with which they interact; one or more communities and the physical environment around them.
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Energy |
The capacity to cause change, especially to do work (to move matter against an opposing force).
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Eukaryote |
Any of the single-celled or multicellular organisms whose cell contains a distinct, membrane-bound nucleus.
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Evolution |
Descent with modification; the idea that living species are descendants of ancestral species that were different from the present-day ones; also defined more narrowly as the change in the genetic composition of a population from generation to generation
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Genes |
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)
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Genetic Information |
The heritable biological information coded in the nucleotide sequences of dna or rna (certain viruses)
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Genetic Variation |
Differences among individuals in the composition of their genes or other DNA segments
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Genus |
A taxonomic category above the species level, designated by the first word of a species’ two-part scientific name.
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Heritable Trait |
A trait or character that is genetically inherited or passed down from generation to generation
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Kingdom |
A taxonomic category, the second broadest after domain.
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Kingdom Animalia |
multicellular; consumers that ingest nutrients |
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Kingdom Archaebacteria |
rare, exotic prokaryotes, live in extreme environments |
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Kingdom Bacteria |
common, widespread prokaryates |
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Kingdom Fungi |
Multi-cellular decomposers, absorb nutrients from the outside
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Kingdom Plantae |
multicellular producers (photosynthetic - convert light energy to chemical energy) |
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Kingdom Protista |
most are single-celled organisms: highly diverse group |
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Metabolism |
The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.
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Mutation |
A change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus.
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Natural Selection |
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
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Nucleus |
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin. (3) A cluster of neurons.
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Nutrient (chemical) Cycling |
a cycle of nutrients among living organisms and the environment
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Organ |
A specialized center of body function composed of several different types of tissues.
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Organ System |
A group of organs that work together in performing vital body functions.
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Population |
A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.
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Producer |
An organism that produces organic compounds from CO2 by harnessing light energy (in photosynthesis) or by oxidizing inorganic chemicals (in chemosynthetic reactions carried out by some prokaryotes).
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Resistance |
fundamental category of taxonomic classification, ranking below a genus or subgenus
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Tissue |
a cellular organizational level intermediate between cells and a complete organ
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variation |
Differences among individuals in the composition of their genes or other DNA segments.
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Active Transport |
The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy.
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Aquaporin |
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane.
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ATP |
An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells.
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Bulk Transport |
The movement of macromolecules such as proteins or polysaccharides into or out of the cell
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Carrier Protein |
In genetics, an individual who is heterozygous at a given genetic locus for a recessively inherited disorder. The heterozygote is generally phenotypically normal for the disorder but can pass on the recessive allele to offspring
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Channel Protein |
protein that allows the transport of specific substances across a cell membrane
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Diffusion |
The random thermal motion of particles of liquids, gases, or solids. In the presence of a concentration or electrochemical gradient, diffusion results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated
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Endocytosis |
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.
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Fluid Mosaic Model |
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids.
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Gated Channels |
A transmembrane protein channel that opens or closes in response to a particular stimulus.
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Concentration Gradient |
A region along which the density of a chemical substance increases or decreases.
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Hypertonic |
Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
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Hypotonic |
Referring to a solution that, when surrounding a cell, will cause the cell to take up water.
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Integral Proteins |
A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein).
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Isotonic |
Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell.
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Lysis |
the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity
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Na-K Pump |
An enzyme found in the plasma membrane of all animal cells that pumps sodium out of cells while pumpingpotassium into cells, both against their concentration gradients
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Osmosis |
The diffusion of free water molecules across a selectively permeable membrane.
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Passive Transport |
The diffusion of a substance across a biological membrane with no expenditure of energy.
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Peripheral Proteins |
A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.
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Phagocytosis |
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells).
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Pinocytosis |
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
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Plasmolysis |
A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment.
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Receptor Protein |
having a high specific affinity for binding agents known to stimulate cellular activity, such as a steroid hormone
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Selectively Permeable |
membrane that will allow certain molecules or ions to pass through it by diffusion
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Signal Transduction |
set of chemical reactions in a cell that occurs when a molecule, such as a hormone, attaches to a receptor on the cell membrane
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Transmembrane Protein |
membrane protein that spans the entirety of the biological membrane to which it is permanently attached.
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Actin |
A globular protein that links into chains, two of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells.
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Autophagy |
process in the body that deals with destruction of cells in the body. It maintains homeostasis or normal functioning by protein degradation and turnover of the destroyed cell organelles for new cell formation
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Cell Wall |
A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of cell walls.
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Chlorophyll |
A green pigment located in membranes within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.
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Chloroplast |
An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water.
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Chromatin |
The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
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Chromosome |
A cellular structure consisting of one DNA molecule and associated protein molecules. (In some contexts, such as genome sequencing, the term may refer to the DNA alone.) A eukaryotic cell typically has multiple, linear chromosomes, which are located in the nucleus. A prokaryotic cell often has a single, circular chromosome, which is found in the nucleoid, a region that is not enclosed by a membrane. See also chromatin.
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Cilia |
A short appendage containing microtubules in eukaryotic cells. A motile cilium is specialized for locomotion or moving fluid past the cell; it is formed from a core of nine outer doublet microtubules and two inner single microtubules (the “9 + 2” arrangement) ensheathed in an extension of the plasma membrane. A primary cilium is usually nonmotile and plays a sensory and signaling role; it lacks the two inner microtubules (the “9 + 0” arrangement).
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Cisternae |
space containing fluid, such as those occurring between the membranes of flattened sacs of the Golgi apparatus and the endoplasmic reticulum, also between the two membranes of the nuclear envelope
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Cytoplasm |
The contents of the cell enclosed by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus.
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Cytoskeleton |
A network of microtubules, microfilaments, and intermediate filaments that extends throughout the cytoplasm and serves a variety of mechanical, transport, and signaling functions.
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Cytosol |
The semifluid portion of the cytoplasm.
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Desmosome |
A type of intercellular junction in animal cells that functions as a rivet, fastening cells together.
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Extracellular Matrix (ECM) |
The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by the cells.
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Endoplasmic Reticulum (Rough) |
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane composed of ribosome-studded (rough)
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Endoplasmic Reticulum (Smooth) |
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membraneand ribosome-free (smooth)
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Flagellum |
A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic flagella have a core with nine outer doublet microtubules and two inner single microtubules (the “9 + 2” arrangement) ensheathed in an extension of the plasma membrane. Prokaryotic flagella have a different structure.
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Gap Junction |
A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells.
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Golgi Apparatus |
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates.
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Glycoproteins |
A protein with one or more covalently attached carbohydrates.
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Intermediate Filaments |
cytoskeletal components found in the cells of vertebrate animal species, and perhaps also in other animals, fungi, plants, and unicellular organisms. They are composed of a family of related proteins sharing common structural and sequence features
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Lysosome |
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.
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Microfilaments |
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction; also known as an actin filament.
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Microtubules |
a tubular aggregate of protein subunits that forms structures, such as the mitotic spindle or the cilia of animal cells or of protozoans, in which the protein interacts with other proteins to generate various cellular movements
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Mitochondria |
spherical or elongated organelle in the cytoplasm of nearly all eukaryotic cells, containing genetic material and many enzymes important for cell metabolism, including those responsible for the conversion of food to usable energy
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Nuclear Envelope |
In a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum.
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Nucleoid |
A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.
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Nulceolus |
A specialized structure in the nucleus consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly. See also ribosome.
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Organelle |
Any of several kinds of membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells.
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Phospholipid Layer |
A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes.
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Plasma Membrane |
The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition.
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Protein Synthesis |
The process by which amino acids are linearly arranged into proteins through the involvement of ribosomal RNA, transfer RNA, messenger RNA, and various enzymes
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Ribosome |
A sphere-shaped structure within the cytoplasm of a cell that is composed of RNA and protein and is the site of protein synthesis
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Tight Junction |
closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid
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Vacuole |
A cavity within the cytoplasm of a cell, surrounded by a single membrane and containing fluid, food, or metabolic waste. Vacuoles are found in the cells of plants, protists, and some primitive animals.
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Vesicle |
a small structure within a cell, consisting of fluid enclosed by a lipid bilayer.Vesicles form naturally during the processes of secretion (exocytosis), uptake (phagocytosis and endocytosis) and transport of materials within the cytoplasm
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