Chapter 5: Key Terms

Question 0

The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input of energy (often as ATP)

Answer 0

Active Transport

Question 1

The part of an enzyme molecule where a substrate molecule attaches (by means of weak chemical bonds); typically, a pocket or groove on the enzyme’s surface

Answer 1

Active Site

Question 2

Main energy source for cells

Answer 2

Adenosine Triphosphate

Question 3

A transport protein in the plasma membrane of some plant or animal cells that
facilitates the diffusion of water across the membrane (osmosis)

Answer 3

Aquaporin

Question 4

The aerobic harvesting of energy from food molecules; the energy- releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form that cells can use to perform work; involves glycolysis, the citric acid cycle, and oxidative phosphorylation (the electron transport chain and chemiosmosis)

Answer 4

Cellular Respiration

Question 5

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

Answer 5

Chemical Energy

Question 6

An organic molecule serving as a cofactor. Most vitamins function as coenzymes in important metabolic reactions

Answer 6

Coenzyme

Question 7

A nonprotein molecule or ion that is required for the proper functioning of an enzyme. See also coenzyme

Answer 7

Cofactor

Question 8

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

Answer 8

Competitive Inhibitor

Question 9

An increase or decrease in the density of a chemical substance in an area. Cells often maintain concentration gradients of ions across their membranes. When a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated

Answer 9

Concentration Gradient

Question 10

The spontaneous tendency of a substance to move down its concentration gradient from where it is more concentrated to where it is less concentrated

Answer 10

Diffusion

Question 11

An energy-requiring chemical reaction, which yields products with more potential energy than the reactants. The amount of energy stored in the products equals the difference between the potential energy in the reactants and that in the products

Answer 11

Endergonic Reaction

Question 12

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

Answer 12

Endocytosis

Question 13

The capacity to perform work, or to rearrange matter

Answer 13

Energy

Question 14

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction

Answer 14

Energy Coupling

Question 15

A measure of disorder. One form of disorder is heat, which is random molecular motion

Answer 15

Entropy

Question 16

A protein (or RNA molecule) that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed into a different molecule in the process

Answer 16

Enzyme

Question 17

An energy-releasing chemical reaction in which the reactants contain more potential energy than the products. The reaction releases an amount of energy equal to the difference in potential energy between the reactants and the products

Answer 17

Exergonic Reaction

Question 18

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

Answer 18

Exocytosis

Question 19

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

Answer 19

Facilitated Diffusion

Question 20

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

Answer 20

Feedback Inhibition