Metabolism and Bioenergetics Flashcards Preview

LDSCI211 (Biochem 1) > Metabolism and Bioenergetics > Flashcards

Flashcards in Metabolism and Bioenergetics Deck (38)
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1
Q

Define metabolism

A

sum of all chemical transformation that occur in living cells

metabolism = catabolism + anabolism

2
Q

1st law of thermodynamics?

A

e=mc^2

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

3
Q

2nd law of thermodynamics?

A

the universe has a tendency to increase disorder.

more disorder = spontaneity

4
Q

3rd law of thermodynamics?

A

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

5
Q

What happens during catabolism?

A

break down of energy containing compounds.

releases energy as ATP and reduced electron carriers (NADH)

6
Q

How can energy be released?

A

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

7
Q

Define Gibbs free energy

A

the energy available in a system

8
Q

What is the Gibbs free energy equation?

A

G = H - TS

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

9
Q

What is enthalpy?

A

heat content reflecting the number and type of bonds

10
Q

What is entropy?

A

extent of disorder in the system

11
Q

do organized systems have high or low entropy?

A

low entropy (low disorder)

12
Q

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

A

negative

yes

13
Q

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

A

positive

no

14
Q

What is delta G naught?

What is delta G prime naught?

A

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

15
Q

what is the delta G in oxidation of glucose?

A

deltaG = -2840kJ/mol

16
Q

is the oxidation of glucose spontaneous or not spontaneous?

A

spontaneous (because negative delta G)

17
Q

what is the terminal electron acceptor?

A

oxygen

because it

18
Q

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

A

T

19
Q

At equilibrium, delta G prime naught = ?

A

delta G prime naught = -RTln(K’eq)

K’eq = products / reactants

20
Q

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

A

directly proportional

21
Q

What does a small or big K’eq mean?

A

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

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

22
Q

why are reactions coupled together?

A

to drive unfavourable steps in a metabolic process

23
Q

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

A

multiply

24
Q

what are referred to as high energy compounds?

A

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

25
Q

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

A
  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)
26
Q

what is solvation

A

formation of sphere of hydration

27
Q

what is a hydride

A

proton with two electrons

H-

transports electrons in biological systems

28
Q

what is the general formula for half cell reactions?

A

Ared Aox + ne-
Box + ne- Bred

overall: Ared+box Bred + Aox

29
Q

what does the equilibrium point for REDOX reactions depend on?

A

relative affinity of Aox and Box for electrons

30
Q

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

A

Fe3+ is the electron acceptor (oxidizing agent)

Cu+ is the e donor (reducing agent

31
Q

which agent has an excess of e-?

A

reducing agent

32
Q

which agent picks up e-?

A

the oxidizing agent

33
Q

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

A

Cu+ Fe2+

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

34
Q

What is E naught?

A

reduction potential tendency to gain electrons

35
Q

does reducing potential decrease or increase down the ETC?

A

decrease

36
Q

what does a large positive Eprime naught mean?

A

bad reducing agent. good oxidizing agent

wants to take electrons

ex: oxygen

37
Q

what does a negative E prime naught mean?

A

good reducing agent. bad oxidizing agent

wants to give away electrons

ex: H2

38
Q

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

A

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