Module 2- Enzymes

Question 1

What is the definition and function of enzymes?

Answer 1

-proteins that speed up reactions in living organisms
-biological catalysts

Question 2

What does the lock and key theory propose?

Answer 2

-that enzyme and substrate fit together perfectly
-the substrate is the key fitting in the enzyme lock

Question 3

What does the induced fit model suggest?

Answer 3

-there is more of a dynamic interaction between enzyme and substrate
-when the enzyme and substrate come together, their interaction causes a small shift in enzyme structure

Question 4

What is the specificity of enzymes determined by?

Answer 4

-every enzyme has a specific active site that is complementary to a specific substrate
-environmental changes can change the tertiary structure of the active site and can stop the enzyme from working properly if it becomes denatured

Question 5

What determines the shape of the active site?

Answer 5

the 3D tertiary structure of the polypeptide chain

Question 6

How does temperature affect enzyme activity?

Answer 6

-increased temperature will increase the kinetic energy of molecules
-this increase the chance of collision between enzyme and substrate and so more collisions are likely in a set amount of time-R.O.R is faster

Question 7

What does the temperature coefficient (Q10) measure?

Answer 7

the change in the rate of reaction when the temperature increase by 10 deg C

Question 8

What is the Q10 generally around?

Answer 8

2

Question 9

How does pH affect enzyme activity?

Answer 9

-changing the pH changes the number of hydroxide and hydrogen ions surrounding the enzyme
-these interact with the charges on the enzymes amino acids which affect hydrogen and ionic bonding resulting in changes to the tertiary structure

Question 10

How does enzyme concentration affect enzyme activity?

Answer 10

-increasing it means there are more enzyme molecules availability to catalyse the substrate in a given amount of time

Question 11

What are coenzymes?

Answer 11

coenzymes are organic molecules that bind to enzymes to increase the speed of the reaction
-are a type of cofactor

Question 12

What are cofactors?

Answer 12

-small molecule that increases the activity of enzymes
-when a cofactor binds to an enzyme it undergoes a conformational change and the enzyme scan now catalyse a reaction
-can be either organic or inorganic

Question 13

What are prosthetic groups?

Answer 13

-inorganic molecules that permanently bind to enzymes to form part of the structure and increase the speed of the reaction
-type of cofactor

Question 14

Give an example of a cofactor

Answer 14

When Cl- binds to amylase it breaks down starch into sugars

Question 15

What does the enzyme amylase do?

Answer 15

amylase in your saliva catalyses the break down of starch into sugars when you eat

Question 16

What is an example of a source for coenzymes?

Answer 16

vitamins are an important source of coenzymes however they are not naturally produced in the body and must be supplied in the diet. If an individual doesn’t have enough vitamins in their diet the enzymes can’t catalyse the necessary reactions so may lead to health problems

Question 17

What are inhibitors?

Answer 17

chemicals that slow down the rate or stop the reaction all together so ESCs can’t be formed or are formed at a much slower rate

Question 18

What do competitive inhibitors do?

Answer 18

-affect the active site directly blocking the access for the formation of ESCs

Question 19

What can help combat the affects of competitive inhibitors?

Answer 19

-increasing substrate concentration can compensate for the effects of a competitive inhibitor as there’s no permanent damage to the shape of the active site

Question 20

Function of non competitive inhibitors?

Answer 20

-some have reversible effects but others are irreversible and denature the enzyme
-they affect another part of the enzyme molecule causing a change to the shape of the active site so it’s no longer complementary to substrate molecules

Question 21

What is an inactive precursor to an enzyme?

Answer 21

zymogen

Question 22

What is the function of a zymogen?

Answer 22

-needs to be cleaved to be activated and the activation is irreversible

Question 23

What does an end product inhibitor do and when is it used?

Answer 23

-product of a reaction acts as an inhibitor to the enzyme that produces it
-this means excess products are not made and resources are not wasted