Exam 2 - Chapter 8

Question 1

Energy

Answer 1

the capacity to do work

Question 2

Work

Answer 2

any activity involving mental or physical effort to achieve a result

Question 3

Kinetic energy

Answer 3

energy of motion

Question 4

Potential energy

Answer 4

stored energy

Food is chemical energy

Question 5

First law of thermodynamics

Answer 5

energy cannot be created or destroyed but it can be changed from one form to another

•Also called law of conservation of energy

Question 6

Second Law of Thermodynamics

Answer 6

with each energy transformation, some energy becomes unable to perform work (usually lost as heat)

•Every energy transformation increases entropy

Question 7

entropy

Answer 7

measure of randomness or disorder in a system

Question 8

Energy transfers

Answer 8

• most energy lost as heat
• sun ultimate source of energy on Earth
• total amount of useable energy decreases as entropy increases

Question 9

Metabolism

Answer 9

all chemical reactions taking place in a cell

Question 10

Metabolic pathway

Answer 10

series of interconnected biochemical reactions which convert a substrate into a product through a series of stepwise reactions

Question 11

Catabolic pathway

Answer 11

release energy by breaking down complex molecules, breaking bonds

Question 12

Anabolic pathway

Answer 12

input of energy required to build up complex molecules from simpler ones, forming bonds

Question 13

Gibbs free energy (G)

Answer 13

amount of energy available to do wor

Question 14

Endergonic reaction

Answer 14

requires an input of energy
non-spontaneous
positive ∆G (energy to do work)
potential energy of products greater than reactants

Question 15

Exergonic reaction

Answer 15

net release of free energy
spontaneous
negative ∆G (energy to do work)
potential energy of reactants is greater than products

Question 16

Equilibrium

Answer 16

cells are open systems which require a constant input of energy, energy coupling between exergonic and endergonic reactions

cells will never reach equilibrium

Question 17

Cellular Work

Answer 17

chemical (endergonic anabolic reactions)
transport (moving materials against chemical gradient)
mechanical (movement)

Question 18

Activation energy (Ea)

Answer 18

• the minimum amount of energy required to get a chemical reaction started
• usually supplied in the form of heat from the surroundings
• The amount of heat that can be absorbed is usually the rate limitingstep of a chemical reaction

Question 19

Transition state

Answer 19

contorted high energy unstable state which must be achieved before a chemical reaction proceeds

Question 20

Enzymes

Answer 20

a catalytic protein that speeds up a reaction without being consumed by the reaction

are very specific

ends in -ase

Question 21

how do enzymes work

Answer 21

by lowering activation energy barrier NOT by changing ∆G, or the energy of the reactants and products

Question 22

Conditions that effect enzyme activity

Answer 22

• substrate concentration (enzyme saturation)
• temperature & pH (optimal ranges, extremes can cause denaturation)
• cofactors & coenzymes

Question 23

Enzyme Activity Controlers

Answer 23

• Inhibitors
• Allosteric regulation
• Feedback inhibition