Metabolism and Bioenergetics

Question 1

Define metabolism

Answer 1

sum of all chemical transformation that occur in living cells

metabolism = catabolism + anabolism

Question 2

1st law of thermodynamics?

Answer 2

e=mc^2

total energy of the universe is constant. It can’t be created or destroyed but can be transformed

Question 3

2nd law of thermodynamics?

Answer 3

the universe has a tendency to increase disorder.

more disorder = spontaneity

Question 4

3rd law of thermodynamics?

Answer 4

as the temp approaches absolute zero (0k or -273.8deg ) atomic motion stops (but electronic motion is not affected)

Question 5

What happens during catabolism?

Answer 5

break down of energy containing compounds.

releases energy as ATP and reduced electron carriers (NADH)

Question 6

How can energy be released?

Answer 6

as ATP of reduced electron carriers: NACH, NACPH, FADH2

Question 7

Define Gibbs free energy

Answer 7

the energy available in a system

Question 8

What is the Gibbs free energy equation?

Answer 8

G = H - TS

H=enthalpy
S=entropy
T=temp in K (25 C = 298k)

Question 9

What is enthalpy?

Answer 9

heat content reflecting the number and type of bonds

Question 10

What is entropy?

Answer 10

extent of disorder in the system

Question 11

do organized systems have high or low entropy?

Answer 11

low entropy (low disorder)

Question 12

When energy is released, what is the sign of delta G? Is this spontaneous?

Answer 12

negative

yes

Question 13

When energy is absorbed, what is the sign of delta G?

Answer 13

positive

no

Question 14

What is delta G naught?

What is delta G prime naught?

Answer 14

standard free energy change at 25C, 1atm, 1M initial conc of solutions. Used by chemists/physicists

biochemical standard free energy change at pH 7. used by biochemists

Question 15

what is the delta G in oxidation of glucose?

Answer 15

deltaG = -2840kJ/mol

Question 16

is the oxidation of glucose spontaneous or not spontaneous?

Answer 16

spontaneous (because negative delta G)

Question 17

what is the terminal electron acceptor?

Answer 17

oxygen

because it

Question 18

delta G gives no information on the reaction rates. T or F?

Answer 18

T

Question 19

At equilibrium, delta G prime naught = ?

Answer 19

delta G prime naught = -RTln(K’eq)

K’eq = products / reactants

Question 20

what is the relationship between delta G prime naught and K’eq?

Answer 20

directly proportional

Question 21

What does a small or big K’eq mean?

Answer 21

small K’eq = +delta G prime naught = not spontaneous = favours substrate

big K’eq = -delta G prime naught = spontaneous = favours product

Question 22

why are reactions coupled together?

Answer 22

to drive unfavourable steps in a metabolic process

Question 23

when you find the overall K’eq, do you multiply or add K’eq values?

Answer 23

multiply

Question 24

what are referred to as high energy compounds?

Answer 24

when delta G prime naught of hydrolysis is bigger than -25kJ/mol

Question 25

What are the 4 chemical basis for the high energy stored in the phosphoanhydride bonds?

Answer 25

1. 4 negative charges (repulsion is from bond stress. hydrolysis releases electrostatic stress) 2. Resonance delocalization of PO4^2- (delocalization = more molecules = more disorder = higher delta S = higher delta G) 3. ADP ionizes releasing H+ (more molecules = increases delta S) 4. ATP hydrolysis increases solvation of ADP and Pi (need less h20 molecules to solvate ATP than inorganic phosphate = increases randomness = increases E)

Question 26

what is solvation

Answer 26

formation of sphere of hydration

Question 27

what is a hydride

Answer 27

proton with two electrons H- transports electrons in biological systems

Question 28

what is the general formula for half cell reactions?

Answer 28

Ared Aox + ne- Box + ne- Bred overall: Ared+box Bred + Aox

Question 29

what does the equilibrium point for REDOX reactions depend on?

Answer 29

relative affinity of Aox and Box for electrons

Question 30

in the reduction of Fe3+ by Cu+, which is the oxidizing and reducing agent?

Answer 30

Fe3+ is the electron acceptor (oxidizing agent) Cu+ is the e donor (reducing agent

Question 31

which agent has an excess of e-?

Answer 31

reducing agent

Question 32

which agent picks up e-?

Answer 32

the oxidizing agent

Question 33

what are the half cell reactions of Fe3+ by Cu+?

Answer 33

Cu+ Fe2+ overall: Fe31+ + cu+ Fe2+ + Cu2+

Question 34

What is E naught?

Answer 34

reduction potential tendency to gain electrons

Question 35

does reducing potential decrease or increase down the ETC?

Answer 35

decrease

Question 36

what does a large positive Eprime naught mean?

Answer 36

bad reducing agent. good oxidizing agent wants to take electrons ex: oxygen

Question 37

what does a negative E prime naught mean?

Answer 37

good reducing agent. bad oxidizing agent wants to give away electrons ex: H2

Question 38

Is the beginning or the end of the ETC a better reducing agent?

Answer 38

the agent in the beginning of the chain will be the best reducing agent. (decreases as you move down)