Bioenergetics

Question 1

Anabolism vs catabolism. use/produce energy?

Answer 1

Anabolism: make macros. use Energy
Catabolism: break macros: produce E!

Question 2

Energy transduction –> 3 steps

Answer 2

Photosynthesis –> cellular respiration –> biological work

Question 3

Bioenergetics definition

Answer 3

quantitative study of energy transductions that occur in living cells/in nature

Question 4

2 laws of thermodynamics

Answer 4

1. conservation of energy; not created or destroyed but transformed. total energy remains constant
2. all spontaneous processes of energy transformation increase entropy of universe

Question 5

What do living systems do to maintain organization? (vs randomness of universe)

Answer 5

Extract useable energy from surroundings and release heat energy back into it

Question 6

Entropy? units

Answer 6

degree of randomness. entropy change: J/mol*k

Question 7

Enthalpy? reflects what? units

Answer 7

Heat content of system –> reflects number and kinds of chemical bonds in reactants and products
Units: J/mol or cal/mol

Question 8

Gibbs free energy? Units. Formula

Answer 8

amount of energy capable of doing work during a reaction.
Units: J/mol
(delta)G = (delta)H - T(delta)S

Question 9

negative vs positive deltaG

Answer 9

negative: reaction is favorable, spontaneous and moves forward –> exergonic
positive: rxn is unfavorable, not spontaneous, backwards –> endergonic

Question 10

delta G = 0 –> (2)

Answer 10

equilibrium –> when rates of forward and reverse reactions are the same

Question 11

positive S and negative H

Answer 11

spontaneous at all temp

Question 12

positive S and positive H

Answer 12

spontaneous at high temp

Question 13

negative S and negative H

Answer 13

spontaneous at low temp

Question 14

negative S and positive H

Answer 14

not spontaneous. Spontaneous backwards

Question 15

(delta)G’° –> what? formula? units?

Answer 15

(delta)G’° = -RT*ln(Keq)
Standard free E change at pH 7
J/mol or Kj/mol

Question 16

Reverse reaction –> what happens to (delta)G and (delta)E

Answer 16

(delta)G –> change sign
(delta)E –> remains the same

Question 17

(delta)G and (delta)E have _____________ relation! small change in (delta)G = ?

Answer 17

exponential
- big change in Keq

Question 18

For a net reaction with multiple half reactions:
Standard free E changes ((delta)G) are ________ VS Keq’ are ___________

Answer 18

(delta)G –> additive
(Keq) –> multiplicative

Question 19

How to drive forward a thermodynamically unfavorable reaction?

Answer 19

By coupling with a highly exergonic reaction through common intermediate!

Question 20

ATP to ADP + Pi is exergonic or endergonic?

Answer 20

Highly exergonic = spontaneous

Question 21

ATP structure (3)

Answer 21

Nitrogenous base (adenine) + ribose sugar + 3 PO4 groups bonded in series through phosphoanhydride bonds

Question 22

Why does ATP have high potential E?

Answer 22

because of 4 negative charges in 3 phosphate groups that repel each other

Question 23

Use of ATP’s energy: minority of cases vs more common

Answer 23

Minority: direct hydrolysis of ATP as energy source for endergonic conformational change
more common: transfer of Pi, PPi or adenyl group to a substrate or enzyme that couples energy of ATP breakdown to endergonic transformation of substances

Question 24

ATP can be recreated from ADP –> how? heterotroph vs autotrophs

Answer 24

Endergonic reaction –> need energy derived from food in heterotrophs and light in autotrophs

Question 25

Why is hydrolysis of ATP highly favorable under standard conditions?

Answer 25

1. better charge separation in products –> relieves electrostatic repulsion of phosphate groups
2. more favorable resonance stabilization of reactants (Pi) –> each of the 4 P-O bond have same degree of double bond
3. higher degree of solvation of products –> less repulsion btw negative charges = better interaction with water

Question 26

How does ATP drive endergonic reaction? (2)

Answer 26

1. substrate bind to specific locations in enzyme (glucokinase, hexokinase)
2. energy transferred during ATP hydrolysis is transferred to substrate by phosphorylation

Question 27

2-step group transfer facilitates ATP dependent reactions (2)

Answer 27

1. phosphoryl group transferred form ATP to glutamate
2. phosphoryl group is displaced by ammonia and replaced as Pi

Question 28

Redox reactions involve ?

Answer 28

electron transfer

Question 29

Oxidation vs reduction

Answer 29

Oxidized = lose electron
reduced = gain electron

Question 30

electron donor = ? agent and oxidized/reduced

Answer 30

reducing agent. and is oxidized

Question 31

electron acceptor = ? agent and oxidized/reduced

Answer 31

oxidizing agent. is reduced

Question 32

2 types of electron “movement”

Answer 32

1. electrons transferred completely from one atom to another
2. electrons shift their position in covalent bonds based on electronegativity of atoms

Question 33

C-C, C-H vs C-O bonds. which has highest potential energy

Answer 33

C-C and C-H: same electronegativity –> high potential E because hold electrons less tightly (share equally)
C-O bonds: O is more negative, holds electrons more tightly –> lower potential E

Question 34

Do carbs or FA or CO2 have more energy?

Answer 34

CO2 < Carbs < FA (bc more C-C and C-H bonds)

Question 35

The more reduced carbon atom is , (more or less) free E is released upon oxidation

Answer 35

more
(CH4 has more energy than CO2)

Question 36

most electron acceptors (lose/gain) potential energy as they are reduced

Answer 36

gain

Question 37

electrons go from (more/less) energetic to (more/less energetic in ETC

Answer 37

less to more

Question 38

Standard reduction potential (E) = ? Units?

Answer 38

measure of molecule’s affinity to electrons. in Volts