ATP Flashcards

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1
Q

What are the endergoni processes in metabolism driven by?

A

The exergonic reactions of nutrient oxidation with mediation by high-energy intermediates.

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2
Q

What is the structure of ATP?

A

An adenosine molecule linked by three phosphoryl groups, seperated by phosphoanhydride bonds.

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3
Q

What are the two general reaction pathways of ATP?

A

ATP + H20 <==> ADP +Pi
ATP + H20 <==> AMP +2 Pi

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4
Q

What is an example of ATP coupling?

A

Hexokinase G phosphorylation forming G6P.

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5
Q

Why is Hexokinase required for G phosphorylation?

A

Pi and G interaction is unfavourable so exergonic hydrolysis of ATP provides thermodynamic favourability.

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6
Q

What are the two key features of phosphoryl-transfer reactions?

A

Kinetic stability to hydrolysis and capacity to transmit large amounts of free energy.

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7
Q

Describe the functional importance of glycolysis in terms of energy?

A

Phosphoryl-transfer potential of glucose to G6P is -16.7kJ whilst PEP dephos to pyruvate is -61.9kJ.

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8
Q

Phosphoryl Transfer Potential

A

The standard free energy of hydrolysis.

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9
Q

What does phosphoryl transfer potential measure?

A

Tendency of phosphorylated compounds to transfer phosphoryl groups to water.

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10
Q

Why does phosphoryl transfer potential fluctuate with pH?

A

Increased divalent cation concentration of say Mg2+ of which has binding affinity for phosphoate.

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11
Q

What is a high energy bond?

A

A bond in which hydrolysis can generate 30kJ of energy to drive unfavourable reactions forwards.

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12
Q

Phosphoanhydride bond

A

A chemical bond formed between two phosphate groups.

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13
Q

What are the three characteristics of phosphoanhydride bonds of its high free energy release?

A

Its ressonance
Electrostatic repulsions between phosphate groups
Low solvation energy.

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14
Q

What does resonance allow for?

A

Electronic delocalisation with greater electronic occupation of volume so lower overall molecular energy.

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15
Q

What is increasing resonance proportional to?

A

More resonance more stability.

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16
Q

When does resonance occur?

A

When a system can store and transfer energy between different storage modes.

17
Q

What causes resonance in phosphoanhydride bonds?

A

The 2 electron withdrawing phosphoryl groups competing for the lone elcetron pair of the oxygen binding.

18
Q

Solvation energy

A

The amount of energy associated with dissolving a solute in a solvent.

19
Q

What makes ATP energetically suited to its function over other phosphate compounds?

A

In a hierarchy is sits in the middle of the rest, thus equally favours hydrolysis and phosphorylation.