1.6

Question 1

Metabolic Pathways

Answer 1

A metabolic pathways is the name given to a series of reactions that occur within a cell
E.g. respiration, protein synthesis and photosynthesis

Question 2

Reversible steps metabolic pathways

Answer 2

Reversible steps in a metabolic pathway prevent over production of an end product.

Question 3

Irreversible steps metabolic pathways

Answer 3

Irreversible steps help to make sure that enough final product is produced.

Question 4

Alternative routes metabolic pathways

Answer 4

A metabolic pathway may use an alternative route if there is a large supply of a particular metabolite (too much for the enzymes in that pathway to cope with) or only a particular substrate available for a metabolic pathway , helps reduce buildup

Question 5

Anabolic reaction

Answer 5

Smaller molecules are joined into a larger molecule

Energy used/required
E.g. protein synthesis

Question 6

Catabolic reaction

Answer 6

Larger molecule broken down into smaller molecules

Energy released
E.g. catalase breakdown of hydrogen peroxide

Question 7

Activation energy

Answer 7

The energy needed to start a reaction is called the activation energy.

Question 8

Enzyme effect on activation energy

Answer 8

Enzymes lower activation energy - they make it easier for the reaction to happen - this speeds the reaction uo

Question 9

Enzymes and affinity

Answer 9

Enzymes and substrates have higher affinity for eachother. They are attracted to eachother. Products hage low affinity for the active site: this means they move away

Question 10

Induced fit

Answer 10

When an enzyme substrate complex is formed, the enzymes active site changes to fit the substrate better.

Question 11

Factors which effect enzyme reaction rate

Answer 11

Temperature
pH
Substrate concentration
Product concentration
Inhibitors

Question 12

Substrate concentration effect on enzyme activity

Answer 12

More substrate present will mean more opportunities for a substrate to collide with an enzyme. When all enzyme molecules are occupied the reaction rate cannot increase

Question 13

Product concentration on enzyme activity

Answer 13

With reversible reactions, sometimes a high product concentration can cause the reaction to slow down or reverse

Question 14

Enzyme inhibitors types

Answer 14

Non competitive
Competitive
Feedback

Question 15

Competitive inhibitors

Answer 15

Competitive inhibitors compete for the active site of the enzyme. It is a similar shape to the active site. If active site occupied, substrate cannot bind, reaction rate slows

Question 16

How to reverse effect of competitive inhibitors

Answer 16

Increase substrate concentration

Question 17

Non-competitive inhibitors

Answer 17

Non competitive inhibitors bind to a different site than the active site but change the shape of the active site. Substrate does not fit.

Question 18

Feedback inhibition

Answer 18

Some products of a metabolic pathway can inhibit an earlier enzyme if their concentrations get too high. This helps to reduce over production of a metabolite / end product .