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Introduction to Genetics & Biochemistry > Bioenergetics - Oxidation, Reduction & Free Energy > Flashcards

Bioenergetics - Oxidation, Reduction & Free Energy Flashcards

1
Q

What synthesise peptide bonds very effectively in translation?

A

Polyribosomes.

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2
Q

The synthesis of peptide bonds by polyribosomes in translation is ‘driven’ by the hydrolysis of which two molecules?

A

ATP and GTP.

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3
Q

When ATP or GTP is hydrolysed, what is added and what is removed?

A

Water is added and phosphate is removed.

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4
Q

ATP is hydrolysed to…?

A

ADP.

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5
Q

GTP is hydrolysed to…?

A

GDP.

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6
Q

What is energy coupling? Give an example.

A

Energy coupling is when the energy released by one reaction is used to ‘drive’ another reaction.

e.g. the energy released by the hydrolysis of GTP is used in the formation of peptide bonds between amino acids to make proteins.

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7
Q

In energy coupling, such as in the use of energy from GTP hydrolysis being used to form peptide bonds between amino acids, what THREE conditions must be met?

A
  1. Overall ΔG must be NEGATIVE.
  2. Free energy must INCREASE.
  3. Entropy must DECREASE.
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8
Q

In theory, how many molecules of ATP or GTP are used to form every peptide bond?

A

Three.

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9
Q

True or false? Creating peptide bonds increases entropy. Why?

A

False. Creating peptide bonds DECREASES entropy, because the amino acids are no longer free roaming. There is less chaos!

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10
Q

The overall ΔG, change in energy, must be what for a reaction to take place?

A

Negative.

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11
Q

If, in theory, there are three molecules of ATP or GTP used to create a peptide bond, how many are used in protein synthesis in real animals?

A

Approximately 10x the theoretical amount!

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12
Q

What are the three components of ATP?

A

Adenosine, ribose and phosphate group(s).

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13
Q

What do the following hydrolyse to?:

ATP -
ADP -
AMP -

A

ATP - ADP
ADP - AMP
AMP - Adenosine.

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14
Q

When ATP4- is ……………… with relief of ……………, it becomes ADP2-.

A

Hydrolysed, charge.

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15
Q

ADP2- can be …………… to form ADP3-.

A

Ionised.

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16
Q

Can the ionisation of ADP2- to ADP3- be reversed?

A

Yes.

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17
Q

Complete the equation:

ATP4- + H2O = …?

A

…ADP3- + Pi2- +H+.

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18
Q

How much energy is released when ATP4- is hydrolysed?

A

ΔG = -31kJ.

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19
Q

When ATP is hydrolysed, …………………. groups are transferred.

A

Phosphate.

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20
Q

What is ‘reference standard’?

A

Reference standard is a way of measuring redox reactions / electron transfer in terms of electricity by measuring the flow of electrons between two different salt solutions.

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21
Q

How does reference standard measure redox reactions?

A

By measuring the flow of electrons between two different salt solutions.

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22
Q

Some redox couples accept electrons, becoming…?

A

Reduced.

23
Q

Some redox couples donate electrons, becoming…?

A

Oxidised.

24
Q

What are standard redox potentials?

A

Standard redox potentials are a league table of redox couples which rank them to predict the likelihood of electrons transferring from one to the other.

25
Q

What is the significance of a redox couple having a high number standard redox potential?

A

It would take a lot of energy for a reaction between the couple to take place, so it is very unlikely that it would happen.

26
Q

Would a redox couple that requires relatively little energy input for a reaction to take place have a high standard redox potential, or a low standard redox potential?

A

A redox couple that requires little energy input for a reaction to take place would have a low standard redox potential.

27
Q

What equation is used to calculate standard redox potentials?

A

The Nernst Equation.

28
Q

Which equation is this?:

E = E0 + (RT/nF)ln(oxidised/reduced)

What does it calculate?

A

This is the Nernst Equation, it calculates standard redox potentials of redox couples.

E - actual potential.
E0 - midpoint potential.
R - gas constant (8.3).
T - absolute temperature.
n - number of electrons transferred.
F - Faraday constant (96,500 j/Vmol).

29
Q

What does this equation show?:

ΔG = -nFΔE0

Where -n is the number of electrons transferred, F is the Faraday constant.

A

This shows that the potential difference between two redox couples (ΔE0) is related to the equilibrium constant (Keq), so the standard free change in energy in a reaction is related to the difference in potential between the couples.

30
Q

What are the two redox couples involved in the electron transfer chain?

A

1/2 O2 and H2O.
NAD+ and NADH.

31
Q

What is the reaction that turns 1/2 O2 into H2O in the electron transfer chain?

A

1/2 O2 + 2H+ + 2e- = H2O.

32
Q

What is the reaction that turns NAD+ into NADH in the electron transfer chain?

A

NAD+ + H+ + 2e- = NADH.

33
Q

Complete the overall reaction that takes place in the electron transfer chain:

1/2 O2 + NADH + H+ …

A

… H2O + NAD+.

34
Q

NADH ………….. electrons to transport them into the ………………… and the electron transfer chain.

A

Stores, mitochondria.

35
Q

True or false? The more energy that is ‘wasted’ in a reaction, the more irreversible that reaction becomes.

A

True.

36
Q

What is ‘active hydrogen’? What has it got to do with NADH and NAD+?

A

Active hydrogen is the electrons that can be transferred back and forth to change NADH to NAD+ and vice versa.

37
Q

Why is the phosphate group not split off from NAD+ when it becomes NADH?

A

It is in the middle of the NAD+ molecule.

38
Q

The relief of charge / charge repulsion between ……………. groups results in ………..-…………… ………………. bonds.

A

Phosphate, high-energy phosphate.

39
Q

What does the ratio of ATP:ADP:AMP equal?

A

The ‘energy charge’ of a cell.

40
Q

ATP needs to be continuously …………………. by other ………………. reactions.

A

Recharged, coupling.

41
Q

ADP and phosphate are produced when ATP is hydrolysed; but can ADP and Pi be used to resynthesise ATP?

A

Yes.

42
Q

NADH and NADPH are more important in plants than mammals - what do they help plants to distinguish?

A

Their energy source - food or photosynthesis.

43
Q

Complete the reaction:

Glucose + 6O2 = …

A

…6CO2 + 6H2O.

44
Q

Complete the reaction:

38ADP + Pi = …

A

…38ATP + 38H2O.

45
Q

How much energy is released in glucose metabolism?:

a. 3,450 kJmol-1.
b. 2,870 kJmol-1.
c. 1,930 kJmol-1.

A

b. 2,870 kJmol-1.

46
Q

How much energy is released in the formation of ATP from ADP and Pi?

a. 5,120 kJmol-1.
b. 2,630 kJmol-1.
c. 1,140kJmol-1.

A

c. 1,140kJmol-1.

47
Q

How does OIL RIG help with oxidation and reduction?

A

Oxidation Is Loss, Reduction Is Gain (of electrons).

48
Q

In oxidation, does charge increase or decrease?

A

Oxidation is loss of electrons, so charge increases.

49
Q

In reduction, does charge increase or decrease?

A

Reduction is gain of electrons, so charge decreases.

50
Q

In open energy systems, what does a ‘sink’ refer to? Give examples.

A

Sources of energy loss. Examples are CO2, H2O, NH4, excretion and radiation into space.

51
Q

Oxidation of foodstuffs can be ………….. to ATP formation.

A

Coupled.

52
Q

Approximately how much energy is stored in ATP’s high energy phosphate bond?

A

30kJ.

53
Q
A

Introduction to Genetics & Biochemistry (21 decks)

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