Chapter 11: Thermodynamics and General Metabolism

Question 1

what is metabolism?

Answer 1

the mechanism of living cells to extract, convert and store energy from nutrients.

Question 2

what is a metabolic pathway?

Answer 2

a series of enzyme-mediated reactions where the product of one reaction is used as the substrate in the next

Question 3

what is Bioenergetics the study of?

Answer 3

study of how cells transform energy, often by producing, storing or consuming adenosine triphosphate (ATP)

Question 4

what does ‘exergonic’ mean?

Answer 4

spontaneous

Question 5

what does ‘endergonic’ mean?

Answer 5

non-spontaneous (the reverse/opposite rxn/interaction is spontaneous

Question 6

does a negative delta H value mean that a rxn/interaction is favorable or UNfavorable?

Answer 6

favorable

Question 7

is a positive delta S value mean that a rxn/interaction is favorable or UNfavorable?

Answer 7

favorable

Question 8

if a rxn/interaction has a negative delta H value and a a postive delta S value, is the rxn/interaction favorable or UN favorable?

Answer 8

favorable

Question 9

what 2 things does a negative delta G value mean?

Answer 9

1. rxn/interaction is spontaneous

2. products have lower energy than substrates (equilibrium leans forward/towards products)

Question 10

are metabolic processes usually spontaneous or NON spontaneous?

Answer 10

They’re usually NON spontaneous (but the non-sponteneity is overcome through coupling rxns)

Question 11

what does it mean to ‘couple’ are rxn?

Answer 11

it means you combine a spontaneous rxn with a non-spontaneous rxn in order to drive the non-spontaneous rxn

the net energy of these couple rxns is negative?

Question 12

why do living organisms use coupled rxns?

Answer 12

to drive otherwise non-spontaneous rxn (that are critical for viability)

Question 13

is the first step of glycolysis an example of a coupled reaction?

Answer 13

yes

Question 14

what is glycolysis?

Answer 14

metabolic process involving the break down of glucose

Question 15

why it ATP so often used as part of coupled rxns?

there are 2 reasons

Answer 15

it is a very high energy molecule

release of each phosphate group is highly energetically favorable

Question 16

what do you call the bond between the phosphate groups in ATP?

Answer 16

phosphoanhydride bond

Question 17

what are 2 ways ATP is used in metabolism?

Answer 17

1. cleaving its phosphate groups (energetically favorable) is coupled with/used to drive non-spontaneous rxns
2. Phosphate groups are used as phosphate sources for phosphorylation rxns

Question 18

what are 4 reasons it’s so energetically favorable to cleave phosphate groups off of ATP?

Answer 18

1. ATP has localized negative charges whose charge-charge repulsion is reduced when phosphate groups are cleaved
2. ADP and AMP have more resonance structures/more delocalization of charges than ATP
3. Breaking ATP into multiple pieces increases entropy
4. Breaking ATP into pieces results in better (favorable) solvation of each piece

Question 19

when you hydrolyze an ATP, are the products lower in energy than the substrate?

Answer 19

yes

Question 20

where do living organism get ATP?

Answer 20

they make it.

they break down larger molecules into smaller molecules to make ATP

Question 21

what are 2 larger molecules whose breakdown can be coupled with ATP synthesis in order to offset the unfavorability of ATP synthesis?

Answer 21

phosphoenolpyruvate

1,3-Bisphosphoglycerate

Question 22

why do we care about thioesters?

Answer 22

they have bonds that release energy similar to when you break the bonds in ATP

Question 23

what is meant by ‘ATP production potential’?

Answer 23

describes the ability to produce ATP

Question 24

are catabolic rxns oxidative or reducing?

Answer 24

oxidatitve

generally: oxidizing carbons

Question 25

are anabolic rxns oxidative or reducing?

Answer 25

reducing

generally: oxidizing carbons

Question 26

what is the significance of reduced NADH?

Answer 26

it has/stores extra electrons that can be used in ATP production

Question 27

what is the difference between catabolic and anobolic metabolism?

Answer 27

catabolic breaks molecules down

anobolic builds molecules up

Question 28

If a rxn’s enthaply is negative and entropy is positive (- +), at what temperatures is it spontaneous?

Answer 28

all temperatures

Question 29

If a rxn’s enthaply is negative and entropy is negative (- -), at what temperatures is it spontaneous?

Answer 29

temperatures lower than T = delta H/delta S

Question 30

If a rxn’s enthaply is positive and entropy is positive (+ +), at what temperatures is it spontaneous?

Answer 30

temperatures ABOVE T = delta H/delta S

Question 31

If a rxn’s enthaply is positive and entropy is negative (+ -), at what temperatures is it spontaneous?

Answer 31

Never.

It is un-spontaneous at all temperatures