Module 2: Section 4 - enzymes

Question 1

what are enzymes

Answer 1

biological catalysts and proteins

Question 2

what is the difference between intracellular and extracellular enzymes

Answer 2

intracellular-within the cell
extracellular-outside the cell

Question 3

what is an example of an intracellular enzyme and what does it do

Answer 3

Catalase is an enzyme that works inside the cells to catalyse the breakdown of hydrogen peroxide to harmless oxygen and water

Question 4

what is hydrogen peroxide

Answer 4

is the toxic by product of several cellular reactions, if left to build up it can kill cells

Question 5

what are extracellular enzyme examples and what do they do

Answer 5

-Amylase and Trypsin
-Amylase catalyses the breakdown of starch to maltose
-Trypsin catalyses the breaking down of peptide bonds

Question 6

what type of proteins are enzymes

Answer 6

Globular

Question 7

what is the specific shape of the active site determined by

Answer 7

enzymes tertiary structure

Question 8

How do enzymes speed up the rate of the reaction

Answer 8

by lowering the activation energy
(its the formation of the enzyme substrate complex that lowers the activation energy)

Question 9

what is activation energy

Answer 9

the minimum amount of energy required for a reaction to occur

Question 10

why does the formation of the enzyme substrate complex cause the activation energy to be lowered

Answer 10

1)if 2 substrate molecules need to be joined, attaching to an enzyme holds them closer together, reducing repulsion between the molecules
2)if enzyme is catalysing a breakdown reaction, fitting inti the enzyme puts a stain on the bonds so it breaks easier

Question 11

explain the lock and key theory

Answer 11

when a substrate binds to a complementary active site and forms an enzyme-substrate complex

Question 12

explain the induced fit model

Answer 12

the substrate and active site a different shapes so as the substate binds the active site changes shape forming an enzyme substrate complex

Question 13

what are the factors that affect enzyme activity

Answer 13

temperature
PH
enzyme concentration
substrate concentration
competitive and non competitive inhibitors

Question 14

how does temp affect enzyme activity

Answer 14

more kinetic energy so molecules move faster so more chances for successful collisions(the energy of the collisions also increases so more likely to result in a reaction)

Question 15

why does a reaction stop if the temperature gets too high

Answer 15

the rise in temp makes the enzymes vibrate more and if the temp is too high the vibration breaks some of the bonds and the active site changes shape

Question 16

what is Q10 also known as

Answer 16

the temperature coefficient

Question 17

what does the temperature coefficient or Q10 show

Answer 17

how much the rate of the reaction changes when the temperature is raised by 10 degrees

Question 18

how does Ph affect enzymes activity

Answer 18

above the optimum Ph the H+ ions and below the optimum PH the OH- ions can mess up the ionic and hydrogen bonds that hold the enzymes tertiary structure in place so the active site changes shape and the enzyme denatures

Question 19

How does enzyme concentration affect the rate of reaction

Answer 19

the more enzyme molecules the more likely the substrate is to collide with on of them and for an enzyme substrate complex.

Question 20

How does the substate concentration affect the rate of the reaction

Answer 20

more substrates so a collision between the substrate and enzyme is more likely. This is until the saturation point(all the active sites are full) and increasing substrate concentration doesn’t make a difference

Question 21

What is a competitive inhibitor?

Answer 21

A competitive inhibitor is a molecule that competes with the substrate for binding to the active site of the enzyme.

-It binds to the active site, preventing the substrate from attaching.
-The effect can be overcome by increasing substrate concentration, as this increases the chance of substrate molecules binding to the enzyme instead.

Question 22

How does a competitive inhibitor affect enzyme activity?

Answer 22

Reduces the rate of reaction because fewer substrate molecules can bind to the enzyme.
The maximum rate of reaction (Vmax) remains the same as if no inhibitor is present, but it takes longer to reach this rate.

Question 23

What is a non-competitive inhibitor?

Answer 23

A non-competitive inhibitor is a molecule that binds to a site other than the active site (called the allosteric site) on the enzyme.

This binding changes the shape of the enzyme and the active site, preventing the substrate from binding effectively, even if the substrate concentration is high.
It does not compete with the substrate for the active site.

Question 24

How does a non-competitive inhibitor affect enzyme activity?

Answer 24

Decreases the rate of reaction because the enzyme’s active site is no longer in the correct shape for substrate binding.
The maximum rate (Vmax) is lowered, meaning the enzyme can never reach the same rate of reaction as without the inhibitor, no matter how much substrate is present.

Question 25

what is a co factor

Answer 25

cofactor is a non-protein substance that helps an enzyme perform its catalytic activity.

Question 26

what are the types of cofactors

Answer 26

organic or inorganic

Question 27

how do inorganic cofactors work

Answer 27

helping the enzyme substrate to bind together

Question 28

do inorganic enzymes get used up and explain

Answer 28

No, as they don’t directly participate in the reaction they are not used up or changed in any way

Question 29

what are organic and inorganic cofactors derived from

Answer 29

organic cofactors are derived for vitamins and inorganic metal ions

Question 30

what are coenzymes

Answer 30

are organic molecules that bind to enzymes to increase the rate of the reaction
(coenzymes are a type of cofactors)

Question 31

do organic enzymes get used up and explain

Answer 31

yes, as they participate in the reaction by often acting as carriers, moving chemical groups between different enzymes

Question 32

what is a prosthetic group

Answer 32

are inorganic molecules that permeant bind to the enzyme to form part of the structure and increase the rate of the reaction
(type of cofactor)

Question 33

what determines weather an inhibitor is reversible or non reversible

Answer 33

strengths of the bonds between the enzyme and inhibitor
if they are strong covalent bonds the inhibitor cant be removed easily so is non reversible and if its weaker hydrogen or ionic its reversible

Question 34

give an example of a non reversible inhibitor and what does it do

Answer 34

Cyanide is a non reversible inhibitor of cytochrome and c oxidase , an enzyme that catalyses respiration reactions

Question 35

Malonate does what

Answer 35

inhibits succinate dehydrogenase which also catalyses respiration reactions

Question 36

What is end-product inhibition?

Answer 36

End-product inhibition is a type of feedback inhibition where the final product of a metabolic pathway inhibits an earlier enzyme in the pathway, preventing overproduction of the product.

Question 37

How does end-product inhibition regulate metabolic pathways?

Answer 37

When the end product accumulates in high concentrations, it binds to an enzyme involved earlier in the pathway, reducing or stopping its activity. This prevents the pathway from producing more of the product than the cell needs.

Question 38

Why is end-product inhibition important?

Answer 38

It helps to regulate the amount of product made in a pathway, preventing the cell from wasting energy and resources by overproducing substances it doesn’t need.

Question 39

How does end-product inhibition work at the molecular level?

Answer 39

The final product of the metabolic pathway binds to an allosteric site on an enzyme involved in the pathway. This binding causes a change in the enzyme’s shape, reducing its ability to bind to the substrate and slowing or stopping the reaction.

Question 40

What type of enzyme is involved in end-product inhibition?

Answer 40

Allosteric enzymes, which have an active site and one or more allosteric sites. The end product binds to the allosteric site, affecting the enzyme’s function.

Question 41

Is end-product inhibition reversible?

Answer 41

Yes, when the concentration of the final product decreases, the inhibition can be reversed, allowing the enzyme to function again and the pathway to continue.