Ch 8

Question 1

Metabolism

Answer 1

the totality of an organism’s chemical reactions

Question 2

The beginning of the metabolic pathway

Answer 2

starting molecule or precursor

Question 3

The end of the metabolic pathway

Answer 3

product

Question 4

The middle steps of the metabolic pathway

Answer 4

intermediates

Question 5

What if the enzyme that catalyzed the reaction that turned C into D was shut off?

Answer 5

buildup of C

Question 6

Types of metabolic pathways

Answer 6

catabolic and anabolic

Question 7

catabolic pathway

Answer 7

release energy by breaking down molecules

Question 8

anabolic pathway

Answer 8

consume energy to build molecules

Question 9

Define energy

Answer 9

the capacity to cause change

Question 10

bioenergetics

Answer 10

the study of how energy flows through living organisms

Question 11

kinetic energy

Answer 11

energy associated with the relative motion of objects

Question 12

potential energy

Answer 12

energy that matter possesses because of its location or structure

Question 13

heat energy

Answer 13

aka thermal, kinetic energy associated with random movement of atoms

Question 14

light energy

Answer 14

powers photosynthesis

Question 15

chemical energy

Answer 15

potential energy available for release in a chemical reaction

Question 16

thermodynamics

Answer 16

study of the energy transformations that occur in a collection of matter

Question 17

First Law of Thermodynamics

Answer 17

Principle of Conservation of Energy: energy can be transferred or transformed, but it cannot be created or destroyed

Question 18

Second Law of Thermodynamics

Answer 18

Every energy transfer or transformation increases the entropy of the universe.

Question 19

Entropy

Answer 19

measure of disorder or randomness

Question 20

spontaneous process

Answer 20

process that can occur without an input of energy, increases the entropy of the universe

Question 21

Gibbs free energy

Answer 21

portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system

Question 22

Symbol for Gibbs free energy

Answer 22

G

Question 23

Change in free energy equation (symbols)

Answer 23

Delta G = Delta H - T Delta S

Question 24

Change in free energy equation (words)

Answer 24

change in free energy is equal to change in enthalpy minus temperature times change in entropy

Question 25

enthalpy

Answer 25

total energy

Question 26

In the delta G equation, temperature is measured in:

Answer 26

Kelvins

Question 27

A spontaneous reaction has a _______ delta G

Answer 27

negative

Question 28

exergonic reaction

Answer 28

net release of free energy, spontaneous, downhill

Question 29

endergonic reaction

Answer 29

absorbs free energy, uphill

Question 30

Exergonic reactions are more likely to occur because

Answer 30

they are spontaneous so don't require energy

Question 31

delta G at equilibrium

Answer 31

zero

Question 32

What happens when a system reaches equilibrium?

Answer 32

no work can be done, cell would be dead

Question 33

List types of work done by living cells

Answer 33

chemical work, transport work, and mechanical work

Question 34

Chemical work

Answer 34

push of endergonic reactions that would not occur spontaneously

Question 35

transport work

Answer 35

pumping of substances across membranes against direction of spontaneous movement

Question 36

mechanical work

Answer 36

beating of cilia, contraction of muscle cells, and movement of chromosomes during cellular reproduction

Question 37

energy coupling

Answer 37

downhill reactions can drive uphill reactions, one way cells manage energy resources

Question 38

Delta G in STP and cellular conditions. Why are they so different?

Answer 38

Standard: -7.3 kcal/mol Cell: -13 kcal/mol (78% greater) So different because cells have greater reactant and product concentrations than 1 M

Question 39

How do phosphorylated intermediates power otherwise impossible reactions?

Answer 39

A phosphorylated intermediate is formed when the phosphate group from an ATP transfers to another molecule like the reactant. The reaction that releases the energy is coupled with an endergonic reaction so that overall they are exergonic.

Question 40

enzymer

Answer 40

macromolecule that acts as a catlyst

Question 41

catalysts

Answer 41

chemical agents that speed up a reaction without being consumed

Question 42

Every chemical reaction involves what two processes?

Answer 42

bond breaking and forming

Question 43

What is activation energy (EA)?

Answer 43

the initial investment of energy required to start a reaction

Question 44

What is activation energy also called and why?

Answer 44

Energy barrier because it is a hill that the reaction must get over

Question 45

Heat or thermal energy is often sufficient to overcome activation energy of many reactions, but what makes heat inappropriate as a "catalyst" in living cells?

Answer 45

could denature the proteins/enzymes

Question 46

What do enzymes do and what don't enzymes do?

Answer 46

DO lower the activation energy barrier | DON'T change delta G

Question 47

What are reactants called in enzymatic reactions?

Answer 47

substrates

Question 48

Glucose and fructose have the same empirical formula but are very different compounds; these are called:

Answer 48

isomers

Question 49

An enzyme binds to a substrate to form:

Answer 49

an enzyme-substrate complex

Question 50

Where on the enzyme does the reaction take place?

Answer 50

active site

Question 51

Describe enzyme interaction with substrate

Answer 51

induced fit: enzyme shapes itself to fit substrate, like a hand in glove rather than a lock and key

Question 52

Mechanisms by which enzymes cause reactions to take place

Answer 52

1. template for substrate orientation 2. stretching and stressing substrates and stabilizing transition state 3. provide favorable microenvironment 4. direct participation in reaction

Question 53

environmental conditions that affect enzyme activity

Answer 53

temperature (37C) and pH (7.4)

Question 54

If environmental conditions reach extreme levels, then the enzymes could:

Answer 54

denature

Question 55

cofactors

Answer 55

nonprotein helpers for catalytic activity (better orient substrates)

Question 56

cofactor examples

Answer 56

metal ions: zinc, copper, iron, magnesium

Question 57

coenzymes

Answer 57

organic molecules cofactors

Question 58

coenzyme examples

Answer 58

vitamins

Question 59

competitive inhibitors

Answer 59

block substrate from entering active site

Question 60

noncompetitive inhibitors

Answer 60

bind to an allosteric site which changes the enzymes shape and makes it less effective

Question 61

How can competitive inhibition be counteracted?

Answer 61

increasing substrate concentration

Question 62

allosteric regulation

Answer 62

protein's function at one site is affected (inhibited or stimulated) by the binding of a regulatory molecule to a separate site

Question 63

How are allosteric regulation and noncompetitive inhibitors related?

Answer 63

both bind to an allosteric site to affect function AR: stabilizes inactive form NI: changes shape

Question 64

feedback inhibition

Answer 64

metabolic pathway shut off by the inhibitory binding of its end product to an enzyme that acts earlier in the pathway

Question 65

Compartmentalization for pathways

Answer 65

multi enzyme complex facilitates a sequence of reaction. often encased in a membrane to ensure that reactions don't affect each other

Question 66

What gives ATP its energy?

Answer 66

phosphate groups because the negative electrons are close together

Question 67

ATP is a:

Answer 67

RNA molecule