Chapter 8 - Bioenergetics and Enzymes

Question 1

define metabolism

Answer 1

consists of chemical reactions by which organisms acquire and use energy and transform materials

Question 2

define catabolic pathway

Answer 2

release energy by breaking down complex molecules into simple molecules

Question 3

define anabolic pathway

Answer 3

consume energy by using simple molecules to build more complex molecules

Question 4

define energy

Answer 4

the capacity to cause change

Question 5

define free energy (G)

Answer 5

energy that can do work in the cell when temperature and pressure are uniform in the system

Question 6

list the 3 types of work in a cell

Answer 6

chemical work, transport work, mechanical work

Question 7

what energy cannot do work?

Answer 7

thermal energy; it is a means to transfer energy but it does not do work

Question 8

define spontaneous reactions

Answer 8

release free energy (change in G is negative)

Question 9

define exergonic

Answer 9

“energy outward”

Question 10

define non-spontaneous reactions

Answer 10

absorb free energy (change in G is positive)

Question 11

define endergonic

Answer 11

“energy inward”

Question 12

define cellular metabolism

Answer 12

the sum of exergonic and endergonic reactions in a cell

Question 13

define energy coupling

Answer 13

using energy released from exergonic reactions to fuel endergonic reactions

Question 14

define kinetic energy

Answer 14

energy contained in a moving mass or particle

Question 15

define potential energy

Answer 15

stored energy

Question 16

define chemical energy

Answer 16

energy stored in chemical bonds

Question 17

define bond energy

Answer 17

the amount of energy required to break a bond (same as amount of energy released when the bond is formed)

Question 18

what is ATP?

Answer 18

adenosine triphosphate; an energy carrier in cells; “energy currencey”

Question 19

what does the hydrolysis of ATP do?

Answer 19

releases energy (is exergonic) because ADP and P is more stable than ATP due to charge repulsion in ATP

Question 20

what enzymes catalyze ATP hydrolysis and why?

Answer 20

ATPases; because the reaction has high activation energy

Question 21

what is the ATP cycle?

Answer 21

ATP synthesis requires energy, ATP hydrolysis releases energy

Question 22

define enzymes

Answer 22

proteins that catalyze biochemical reactions by lowering activation energy without being consumed by the reaction

Question 23

define “active site”

Answer 23

the small part of an enzyme that binds to its substrate

Question 24

define “induced fit”

Answer 24

substrate binding causes a change in the shape of the active site

Question 25

how can enzymes lower activation energy?

Answer 25

holding the reactants in a good orientation, providing a suitable micro-environment, directly employing amino acid side-chains

Question 26

list the factors that affect enzyme activity

Answer 26

substrate concentration, temperature, pH

Question 27

define cofactors

Answer 27

small, non-proteinaceous molecules required by some enzymes for catalytic activity - may bind to the active site tightly or loosely

Question 28

define competitive inhibitors

Answer 28

competes to bind to the active site

Question 29

define non-competitive inhibitors

Answer 29

change enzyme shape by binding somewhere that isn’t the active site

Question 30

define feedback inhibition

Answer 30

the product of a pathway inhibits the first enzyme of the pathway

Question 31

define negative feedback

Answer 31

as the concentration of product builds up, the product molecules themselves inhibit the process that induced them