chapter 5

Question 1

fluid mosaic model

Answer 1

The currently accepted model of cell membrane structure, depicting the membrane as a mosaic of protein molecules, suspended in a fluid bilayer of phospholipid molecules

Question 2

selective permeability

Answer 2

A property of biological membranes that allows them to regulate the passage of substances across them

Question 3

diffusion

Answer 3

The tendency for particles of any substance to spread out into the available space

Question 4

concentration gradient

Answer 4

A gradual difference in the concentration of solute in a solution between two regions

Question 5

passive transport

Answer 5

The diffusion of a substance across a biological membrane with no energy

Question 6

osmosis

Answer 6

The diffusion of free water across the selective permeable membrane

Question 7

tonicity

Answer 7

The ability of a solution surrounding a cell to cause that cell to gain or lose water

Question 8

isotonic

Answer 8

Referring to a solution that when surrounding a cell causes no net movement of water into or out of the cell

Question 9

hypotonic

Answer 9

referring to a solution that went surrounding a cell will cause the cell to take up water

Question 10

hypertonic

Answer 10

referring to solution that went surrounding a cell will cause the cell to lose water

Question 11

facilitated diffusion

Answer 11

The passage of a substance, the specific transport protein across a biological membrane down its concentration gradient

Question 12

osmoregulation

Answer 12

The homeostatic maintenance of solute, concentration and water balance by a cell an organism

Question 13

aquaporin

Answer 13

A transport protein in the plasma membrane of an animal plant or microorganism cell that facilitates the diffusion of water across the membrane

Question 14

active transport

Answer 14

The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring energy

Question 15

exocytosis

Answer 15

The movement of materials out of a cell by the fusion of vesicles with the plasma membrane

Question 16

endocytosis

Answer 16

Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane

Question 17

phagocytosis

Answer 17

Cellular eating a type of endocytosis in which a cell engulf macromolecules other cells or particles into the cytoplasm

Question 18

receptor-mediated endocytosis

Answer 18

The movement of specific molecules into a cell by infolding of vesicles containing proteins with receptor site specific to the molecules being taken in

Question 19

kinetic energy

Answer 19

The energy associated with the motion of objects, moving matter, does work by imparting motion to other matter

Question 20

thermal energy

Answer 20

kinetic energy due to the random motion of atoms and molecules energy in its most random form

Question 21

heat

Answer 21

thermal energy in transfer from one body of matter to another

Question 22

potential energy

Answer 22

The energy that matter possesses because of its location or spatial arrangement, water behind a dam possesses potential energy and so do chemical bonds

Question 23

chemical energy

Answer 23

Energy available in molecules for release in a chemical reaction a form of potential energy

Question 24

thermodynamics

Answer 24

The study of energy transformation that occurs in a collection of matter

Question 25

first law of thermodynamics

Answer 25

The principle of conservation of energy energy can be transferred and transformed, but cannot be created or destroyed

Question 26

entropy

Answer 26

A measure of disorder or randomness

Question 27

second law of thermodynamics

Answer 27

The principal stating that every energy conservation reduces the order of the universe, increasing its entropy. ordered forms of energy are at least, partly converted to heat

Question 28

exergonic reaction

Answer 28

an energy releasing chemical reaction in which the reactants contain more potential energy than the products

Question 29

endergonic reaction

Answer 29

an energy requiring chemical reaction which yields products with more potential energy than the reactants

Question 30

metabolism

Answer 30

the totality of an organisms chemical reaction

Question 31

metabolic pathway

Answer 31

A series of chemical reactions that either builds a complex molecule or breaks down a complex molecule in to simple compounds

Question 32

energy coupling

Answer 32

in cellular metabolism, the use of energy released from an exogenic reaction to drive an endogenic reaction

Question 33

ATP

Answer 33

adenosine triphosphate the main energy source for cells. ATP releases energy when its phosphate bonds are hydrolyzed.

Question 34

phosphorylation

Answer 34

The transfer of a phosphate group usually from ATP to a molecule nearly all cellular work, depends on ATP energizing other molecules by phosphorylation

Question 35

activation energy

Answer 35

The amount of energy that reactants must absorb before a chemical reaction will start

Question 36

enzymes

Answer 36

A macromolecule usually a protein that serves as a biological catalyst, changing the rate of a chemical reaction without being consumed by the reaction

Question 37

substrate

Answer 37

A specific substance (reactant) on which an enzyme acts. Each enzyme recognizes only the specific substrate of the reaction a catalyzes. A surface in or on which an organism lives.

Question 38

active site

Answer 38

The part of an enzyme where a substrate molecule attaches

Question 39

induced fit

Answer 39

The change in shape of the active site of an enzyme caused by entry of the substrate so that it finds the substrate snuggly

Question 40

cofactor

Answer 40

A non-protein molecule or ion that is required for the proper functioning of an enzyme

Question 41

coenzyme

Answer 41

an organic molecule serving as a cofactor. Most vitamins function as co-enzymes in important metabolic reactions.

Question 42

competitive inhibitor

Answer 42

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate. A competitive inhibitor structure mimics that of an enzyme substrate.

Question 43

feedback inhibition

Answer 43

A method of metabolic control in which a product of a metabolic pathway act as an inhibitor of an enzyme within that pathway

Question 44

noncompetitive inhibitor

Answer 44

A substance that reduces the activity of an enzyme without entering an active site. By binding elsewhere on the enzyme, a non-competitive inhibitor changes the shape of the enzyme so that the active site no longer effectively catalyze the conversion of substrate to product.