Biology Terms Chapter 4 And 5

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chromosome

Back 1

a structure that consists of DNA and associated proteins; carries part or all of the cell's genetic information

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chromatin

Back 2

collective term for DNA molecules together with their associated proteins

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endomembrane system

Back 3

series of interacting organelles (endoplasmic reticulum, Golgi bodies, vesicles) between nucleus and plasma membrane; produces lipids, proteins.

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endoplasmic reticulum

Back 4

organelle that is a continuous system of sacs and tubes; extension of the nuclear envelope. Smooth ER makes lipids and breaks down carbohydrates and fatty acids; rough ER modifies polypeptides made by ribosomes on its surface.

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vesicles

Back 5

small, membrane-enclosed, saclike organelle; different kinds store, transport, or degrade their contents

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peroxisomes

Back 6

enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxic substance

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lysosomes

Back 7

enzyme-filled vesicle that functions in intracellular digestion

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vacuoles

Back 8

a fluid-filled organelle that isolates or disposes of waste, debris, or toxic materials

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central vacuole

Back 9

fluid-filled vesicle in many plant cells

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golgi body

Back 10

organelle that modifies polypeptides and lipids; also sorts and packages the finished products into vesicles

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mitochondria

Back 11

organelle that produces ATP by aerobic respiration in eukaryotes

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plastids

Back 12

category of double-membrane organelle in plants and algal cells. Different types specialize in storage or photosynthesis; e.g., chloroplast, amlyoplast

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chloroplasts

Back 13

organelle of photosynthesis in the cells of plants and many protists

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cytoskeleton

Back 14

dynamic framework of protein filaments that support, organize, and move eukaryotic cells and their internal structure

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microtubules

Back 15

cytoskeletal element involved in cellular movement; hollow filament of tubulin subunits

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microfilaments

Back 16

reinforcing cytoskeletal element; a fiber of actin subunits

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cell cortex

Back 17

reinforcing mesh of cytoskeletal elements under a plasma membrane

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intermediate filaments

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stable cytoskeletal element that structurally supports cells and tissues

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motor proteins

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type of energy using protein that interacts with cytoskeletal elements to move the cell's parts or whole cell

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cilium

Back 20

short, movable structure that projects from the plasma membrane of some eukaryotic cells

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centriole

Back 21

barrel-shaped organelle from which microtubules grow

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basal body

Back 22

organelle that develops from a centriole

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pseudopods

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a temporary protrusion that helps some eukaryotic cells move and engulf prey

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extracellular matrix (ECM)

Back 24

complex mixture of cell secretions; supports cells and tissues; has roles in cell signaling

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primary wall

Back 25

the first cell wall of young plant cells

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secondary wall

Back 26

lignin-reinforced wall that forms inside the primary wall of a plant cell

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lignin

Back 27

material that stiffens cell walls of vascular plants

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cuticle

Back 28

secreted covering at a body surface

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cell junctions

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structure that connects a cell to another cell or to extracellular matrix

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plasmodesmata

Back 30

cell junctions that connect the cytoplasm of adjacent plant cells

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tight junctions

Back 31

arrays of fibrous proteins; join epithelial cells and collectively prevent fluids from leaking between them

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adhering junctions

Back 32

cell junction composed of adhesion proteins; anchors cells to each other and extracellular matrix

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gap junctions

Back 33

cell junction that forms a channel across the plasma membrane of adjoining animal cells

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energy

Back 34

the capacity to do work

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kinetic energy

Back 35

the energy of motion

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first law of thermodynamics

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energy cannot be created or destroyed

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second law of thermodynamics

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energy tends to disperse spontaneously

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entropy

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measure of how much the energy of a system is dispersed

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potential energy

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stored energy

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reactants

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a molecule that enters a reaction

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products

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a molecule that remains at the end of a reaction

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endergonic

Back 42

describes a reaction that requires a net input of free energy to proceed (energy in)

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exergonic

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describes a reaction that ends with a net release of free energy (energy out)

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activation energy

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minimum amount of energy required to start a reaction

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catalysis

Back 45

the acceleration of a reaction by a molecule that is unchanged by participating in the reaction

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substrates

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a molecule that is specifically acted upon by an enzyme

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active sites

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of an enzyme, pocket in which substrates bind and a reaction occurs

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transition state

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point during a reaction at which substrate bonds reach their breaking point and the reaction will run spontaneously

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induced-fit model

Back 49

the concept that substrate binding to an active sit of an enzyme improves the fit between the two molecules

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metabolic pathway

Back 50

series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule

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feedback inhibition

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mechanism in which a change that results from some activity decreases or stops the activity

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allosteric

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describes a region of an enzyme that can bind a regulatory molecule and is not the active site

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redox reaction (oxidation reduction reactions)

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oxidation reduction reaction, in which one molecule accepts electrons (it becomes reduced) from another molecule (which becomes oxidized)

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electron transfer chain

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array of enzymes and other molecules that accept and give up electrons in sequence, thus releasing the energy of the electrons in usable increments

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anabolic pathways

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these pathways build molecules

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catabolic pathways

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these pathways break molecules

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cyclic pathway

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these pathways regenerate a molecule from the first step

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antioxidant

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substance that prevents oxidation of other molecules

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cofactor

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a metal ion or a coenzyme that associates with an enzyme and is necessary for its function

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coenzyme

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an organic molecule that is a cofactor

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phosphorylation

Back 61

transfer of a phosphate group from one molecule to another

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ATP

Back 62

the nucleotide adenosine triphosphate

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ATD/ADP cycle

Back 63

process by which cells regenerate ATP. ADP forms when ATP loses a phosphate group, then ATP forms again as ADP gains a phosphate group

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fluid mosaic

Back 64

model of a cell membrane as a two dimensional fluid of mixed composition

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adhesion proteins

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membrane protein that helps cells stick together in animal tissues

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recognition proteins

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plasma membrane protein that identifies a cell as belonging to self (one's own body)

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receptor protein

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plasma membrane protein that binds to a particular substance outside of the cell

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transport proteins

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protein that passively or actively assists specific ions or molecules accross a membrane

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diffusion

Back 69

spontaneous spreading of molecules or ions in a liquid or gas

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concentration

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number of molecules or ions per unit volume

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concentration gradient

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difference in concentration between adjoining regions of fluid

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hypotonic

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describes a fluid that has low overall solute concentration relative to another fluid

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hypertonic

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describes a fluid that has a high overall solute concentration relative to another fluid

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isotonic

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describes two fluids with identical solute concentrations

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osmosis

Back 75

the diffusion of water accross a selectivity permeable membrane in response to a concentration gradient

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turgor

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pressure that a fluid exerts against a wall, membrane, or other structure that contains it

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osmotic pressure

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amount of turgor that prevents osmosis into cytoplasm or other hypertonic fluid

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passive transport

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mechanism by which a concentration gradient drives the movement of a solute accross a cell membrane through a transport protein. Requires no energy input.

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active transport

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energy-requiring mechanism in which a transport protein pumps a solute accross a cell membrane against its concentration gradient

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calcium pump

Back 80

active transport protein; pumps calcium ions accross a cell membrane against their concentration gradient

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exocytosis

Back 81

process by which a cell expels a vesicle's contents to extracellular fluid

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endocytosis

Back 82

process by which a cell takes in a small amount of extracellular fluid by ballooning inward of its plasma membrane

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phagocytosis

Back 83

"cell eating"; an endocytic pathway by which a cell engulfs particles such as microbes or other cellular debris

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pinocytosis

Back 84

endocytosis of bulk materials