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Flashcards in Cell metabolism Deck (17)
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1
Q

The oxidation of Acetyl CoA provides

A

Large amounts of ATP

2
Q

What is the purpose of enzymes

A

Increase reaction rate without being consumed

3
Q

Describe enzymes

A

Not consumed, highly selective, bind specific substrate for 1 reaction. Usually named by substrate and -ase

4
Q

What is the Michaelis constant?

A

The concentration of a substrate that results in half-max reaction velocity. A high kM indicates a low affinity and a low kM indicates a high substrate-enzyme affinity

5
Q

What is a regulatory mechanism for enzymatic pathways?

A

Substrates are usually present in concentrations near their kM, so small changes in substrate concentration result in tight control of the pathway

6
Q

What is the main role of enzymes?

A

Decrease energy of activation for reaction

7
Q

What does the regulatory enzyme do?

A

Rate limiting step, committed step in reaction

8
Q

Are rate limiting enzymes always committed steps?

A

Yes, but committed steps are not always rate limiting

9
Q

What factors can affect enzyme activity?

A

pH and Temperature (positive relationship)

10
Q

Describe the enzyme activation pathway

A

Pronezymes (zygomens, not active) are activated to active enzymes. The activation of this enzyme may activate other enzymes from proenzymes (amplification pathway)

11
Q

Name enzyme regulatory roles

A

Controlling rate limiting steps, controlling committed steps, negative feedback on enzyme by excess subtrate

12
Q

Describe allosteric control of enzymes

A

A substrate will bind to a ligand at a place other than the active site on an enzyme and either up-regulate or down-regulate enzyme activity by changing enzynme’s affinity for the substrate

13
Q

Describe positive and negative feedback

A

An excess of product [B] will down regulate the enzyme, an excess of substrate [A] will upregulate the enzyme

14
Q

Name types of enzyme control

A

pH, temperature, Gentic control (slowest, via transcription), covalent modification (phosphorylation), allosteric (non-covalent ligand) control

15
Q

Name types of enzymes and function

A

Kinase (phosphorylation), Dehydrogenase (removal of hydrogen), Mutase (transfers functional group), Isomerase (converts ketose to aldose), Enolase ( dehydration)

16
Q

Characteristics of co-enzymes

A

Low molecular weight, non-protein and vitamin derivatives. Co-enzymes act as substrates in 2 substrate reactions. Co-enzymes are chemicaly altered during the reaction and then return to their original state

17
Q

How to calculate free energy change

A

^G Products - ^G Reactants