Biology Test 2

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Cell

Back 1

"the structural and functional unit of an organism; the smallest structure capable ofperforming all the functions necessary for life."

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Unicellular

Back 2

an organism composed of a single cell.

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Multicellular

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an organism composed of many cells.

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Cytology

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(or cell biology) the science involved with the study of the cell.

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Robert Hooke

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first used word cell to describe the compartments he saw in cork underhis microscope.

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Anton van Leeuwenhoek

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first described living cells

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Matthias Schleiden

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stated that plants are composed of cells.

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Theodor Schwann

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stated that animals are composed of cells

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Rudolf Virchow

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stated that cells come only from pre-existing cells (bio genesis: lifebegins from life).

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Louis Pasteur

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disproved the theory of spontaneous generation (life from non-life), aview held even by scientists for many centuries.

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Cell Theory

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all living things are composed of cells, and (2) all living cells arise from pre-existingliving cells.

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Microscopy

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cells, except for a few, are generally too small to see with the naked eye. Thedevelopment and use of the microscope was essential for the study of cells

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Resolution

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the ability to distinguish two small objects set close together as separate objects.

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Naked eye

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able to see (resolve) something as small as about 150 microns (100-200 microns).[1 micron = 0.001 mm] micron = micrometer = ìm

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Light microscope

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gives a view of general detail at the cell level--not much of internal cellstructure. Resolution to 0.2 microns. Limited by the wavelength of visible light. Magnificationlimit about 1600 X (Most microscopes available provide 1000X.)

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Photomicrograph

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picture taken through a light microscope

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Electron microscope

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Uses a beam of electrons for illumination instead of visible light. Provides a highly detailedview of cell structure

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Transmission E.M

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view of interior structure. Resolution to less than 1 Angstrom (.1 nm)[1 nano-meter (nm) = 0.001 micron (ìm)]

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Scanning E. M

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view of surface details.Resolution to 1-5 nm

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Advantages of E. M

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(1) Better magnification: bigger picture.

(2) Better resolution: sharper picture.

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Electron micrograph:

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picture taken with electron microscope

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Common Features of All Cells

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1. DNA is the cell's genetic information

2. RNA participates in t he production of proteins

3. Ribosomes are structures that manufacture proteins

4. Proteins carry out all of the cell's work

5. Cytoplasm is the fluid substance that occupies much of the volume of the cell

6. Cell Membrane (or plasma membrane) forms a boundary between the cell and its environment

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Size of Cells

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Prokaryotic Cells: 1 - 10 microns in diameter. Eukaryotic Cells: 10 - 100 microns

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Why are cells so small?

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Surface to volume ratio. Nutrients enter, waste exits. The larger the cell the more nutrients are needed. At a certain weight the cell cannot pass nutrients and waste to support the needs of the cell.

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Largest cell in human body

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Ovum (egg)...10-100 trillion human cells in our bodies.

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Prokaryotic

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Before nucleus, domain Archean and bacteria. All are unicellular.

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Eukaryotic

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possessing a membrane-bound nucleus and other organelles: DNA is located in a membrane bound structure called the nucleus

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Organelles:

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("little organs") specialized structures in the cell performing specific cellularfunctions. Examples: the four kingdoms of Domain Eukarya: Plantae, Animalia, Fungi, Protista

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Structure of prokaryotic (external)

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cell membrane, cell wall, capsule (adds protection), flagella, pili (attachment)

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Structure of prokaryotic (internal)

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Nucleoid (where chromosome is), chromosome (DNA), Plasmids (segments of DNA in cytoplasm), ribosomes (protein production), Thylakoids (sacs with chlorophyll and help photosynthesis)

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Eukaryotic Cell Structure

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All cells are surrounded by a barrier that separates the contents of the cell from the environment outside the cell. Thin, weak.

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Functions of the cell membrane

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Encloses cell to maintain wholeness, controls passage in and out of cell, and receives and responds to external stimuli.

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composition of the cell membrane

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phospholipid bilayer, protein, and most contain a steroid.

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Phospholipid Bilayer

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2 layers arranged head (hydrophilic) out, tail (hydrophobic) in. Interior is fatty acids (lipid) like light oil. Molecules are able to move around, pull apart, and reform.

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Protein

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Form a mosiac pattern and vary in shape, size, location and function.

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Steroid

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Humans and other animals have cholesterol which strengthens the membrane.

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Fluid Mosaic Model

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Current model of membrane structure. Proposed by S. Singer andG. Nicolson in 1972. Phospholipid bilayer has oily, fluid consistency, proteins are scattered in amosaic pattern

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What do carb chains attach to to form?

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Glycolipids and glycoproteins

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Transport proteins

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Form passageways through which substances may cross the membrane. May be an open channel or the protein may combine with substance to help it move across the membrane.

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Enzymes

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Make chemistry happen. Carry out metabolic reactions.

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Recognition proteins

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Glycoprotein. Cell-to-cell recognition, immune system recognizes its own cellls. Allows our bodies to get rid of foreign cells.

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Adhesion proteins

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Membrane proteins that enable cells to stick to one another.

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Receptor Proteins

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special shape allows specific molecule to fit into it that may cause protein make a specific cellular response

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Endomembrane system

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Interconnected intra-cellular system of membrane boundorganelles. composed of nuclear envelope, ER, Golgi Apparatus, and various vesicles. Divides cell into functional areas and restricts chemical reactions to specific places.

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Nucleus

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stores the genetic material which then directs cell activities; "Control Center of theCell": without a nucleus, eukaryotic cells cannot continue to function for long, and cannotreproduce themselves.

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nuclear envelope

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double layered membrane

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Nuclear pores

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channels through which certain substances can readily enter/leave thenucleus.

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Nucleolus

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one or more small bodies within the nucleus;an area specialized for ribosomal RNA synthesis; an area of concentrated RNA.

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Chromatin

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long threadlike strands of genetic material in a non-dividing cell

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Chromosomes:

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visible bodies formed when the genetic material coils and shortensduring cell reproduction (mitosis & meiosis).

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Gene:

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a single genetic instruction; a single functional unit of a DNA molecule.; thebasic "unit of heredity

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Ribosomes

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Small particles of RNA/Protein, protein synthesis in the cell**, may be free in cytoplasm or attached to the ER

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Endoplasmic Reticulum

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Complicated system of membranous channels and saccules (little membrane bound sacs) andtubules (little tubes)

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Rough ER

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ER with attached ribosomes. Involved in protein synthesis (provides a "worksurface" for ribosomes), modification of newly formed protein, and transport of same to other locations in cell.Abundant in cells secreting protein products

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Smooth ER

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Various functions depending on cell type. Synthesizes phospholipids to produce newmembrane. Produces testosterone (male), estrogen (female) and other lipids. Involved inlipid and steroid metabolism. Abundant in cells secreting steroid based hormones.

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transport vesicles

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small membrane bound structures for transporting large moleculesfrom the ER to other locations within the cell.

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Golgi Apparatus

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processing, packaging, storage, and distribution

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Secretory vesicles/Transport vesicles

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membrane bound vesicles formed by the Golgi apparatus; contains materialto be released from cell; vesicle moves to cell membrane, merges with it and releasessubstance.

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Lysosomes

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Contain digestive enzymes, functions in digestion and auto digestion (self digestion)

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Phagocytosis

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a process by which some cells engulf particles

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Vacuoles

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large membrane bound sacs (a vesicle is a small vacuole). Found sometimes in animalcells but much more prominent in plant cells

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central vacuoles

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May contain chemicals to function like animals, support cell by turgor pressure, storage, may contain toxins to protects against the plant being eaten.

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Functions of Vacuoles

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Degrade or recycle enzymes

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Contractile Vacuoles

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specialized for ridding cell of excess water

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Food Vacuoles

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Specialized for breaking down nutrients

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What are peroxisomes?

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Similar to lysosomes; contain enzymes that form hydrogen peroxide; especially prevalent in cells that are synthesizing or breaking down fats.

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Chloroplast Function

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Photosynthesis; solar energy to chemical energy

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What is chlorophyll?

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The actual chemical molecule that captures solar energy for photosynthesis to occur. Located in the thylakoid membranes

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Reaction of photosynthesis

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Glucose

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How many layers of membrane surround the chloroplast?

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Double (2)

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Stroma

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space

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Thylakoid

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stacked like pancakes; flattened sacs

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Granum

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stacks of thylakoid

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Amyloplasts. What do they contain and where can they be found?

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organelles that store starch; common in roots of plants, potatoes, and corn kernals

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chromoplasts? What do they contain and where can they be found?

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organelles that store pigments, particularly red, orange, and yellow; common in leaves; (autumn)

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Plastids

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Contain their own DNA and ribosomes

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Nickname for mitochondria

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Powerhouse of the cell

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Site of major reactions of cellular respiration

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Mitochondria

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What is cellular respiration?

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the process by which chemical energy of carbs is converted to ATP

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General reaction of Cell Respiration

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Carbon dioxide, water, and energy

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ATP

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Storage of energy in covalent bonds then using the energy to power reactions

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Do all organisms have mitochondria?

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Yes

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How many layers of membrane surround the mitochondrion?

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2 layers; outer and inner

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Matrix

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space

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Cristae

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Folds of inner membrane

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Do mitochondria have their own DNA and ribosomes?

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yes

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Cytoskelton

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network of protein tracks and tubes - transports, physical support, aids in cell division, helps connect cells, and enables movement

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Microfilaments

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long rods of protein acid, about 7 nano meters, that help with muscle contraction, strength, and anchorage to other cells.

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Intermediate filaments

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10 nano meters, variety of proteins, cell shape by forming in cytosol and resisting mechanical stress, and help bind some cells together

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microtubules

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23 nano meters, track way, motor proteins. centrosomes organize micorotubules that produce cilia and flagella.

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How are micro tubules related to the spindle in cell division?

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Microtubules form the spindle in dividing cells.

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Cilia

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hair-like projections which function in movement. Shorter and usually more numerous. EX: Paramecium & Lining of respiratory tract

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Flagella

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Typically long and few in number. Hair-like projections which function in movement. EX: Sperm, Euglena, Volvox

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Cell Wall

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A rigid, protective wall outside the cell membrane. Supports and gives strength to cell, holds the cell shape, prevents cell from bursting when there's too much water

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Cellulose

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In cell wall to add strength

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Lignin

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Adds strength to cell wall

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Chitin

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Adds strength to cell wall

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Plasmodesmata

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Channels that connect adjacent plant cells - "tunnels"

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Tight Junction

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Form impermeable barrier between cells - join cells into sheets. (allow body to control biochemical movement)

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Anchoring Junction

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Animal cells connect to neighbors like a rivet. Proteins span cell membrane and link each cells cytoskelton. (hold skin cells in place by anchoring them to extracellular matrix - space -)

Front 101

Gap junction

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Protein channel that links cytoplasm of adjacent cells to exchange ions, nutrients, and other small molecules. Allows groups of cells to contract together, such as the heart.

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What doesn't have cell walls?

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Animals and some protists