Chapter 4: Enzymes

Question 1

What is an enzyme?

Answer 1

Biological protein. Globular proteins that interact with substrate molecules causing them to react. Without them we would die

Question 2

What is an anabolic enzyme?

Answer 2

Building up of molecules from smaller ones to larger ones

Question 3

What is a catabolic enzyme?

Answer 3

The breaking down of molecules from larger ones to smaller ones. Eg: Digestion

Question 4

Factors that affect enzyme activity?

Answer 4

Temperature, pH, concentration, pressure

Question 5

What is activation energy?

Answer 5

The minimum amount of energy needed to start a reaction

Question 6

Describe the Lock and Key model?

Answer 6

Enzyme has a tertiary structure with a complementary shape to a specific substrate molecule. This is called the active site. When substrate binds it’s called the enzyme-substrate complex then it reacts and forms the enzyme-product complex. The products then get released. There R-groups within the active site of the enzyme interact with substrate and form temporary bonds

Question 7

Explain the induced-fit hypothesis?

Answer 7

When an enzyme’s active site actually changes shape slightly as the substrate enters. Initial reaction between enzyme and substrate is relatively weak but then the interactions rapidly induce changes in the tertiary structure and strengthen. It lowers the activation energy

Question 8

What is an intracellular enzyme and examples?

Answer 8

An enzyme that acts within cells. The enzyme catalase ensures hydrogen peroxide is broken down into oxygen and water, preventing accumulation. IN animals and plants

Question 9

What is an extracellular enzyme example

Answer 9

Enzymes outside of cells that break larger molecules into smaller ones.

Question 10

How do single-celled organisms receive nutrients?

Answer 10

They release enzymes into the immediate environment and break down larger molecules such as proteins into amino acids and glucose to be absorbed into bloodstream

Question 11

How is starch digested?

Answer 11

Starch polymers are broken down into maltose with the enzyme amylase. Produced in the salivary gland. Maltose is then broken down into glucose. With the enzyme maltase.

Question 12

How are proteins digested?

Answer 12

Trypsin is a protease. A type of enzyme that catalyses the digestion of proteins into smaller peptides which is then broken down into amino acids. Trypsin is produced in the small intestine

Question 13

What does Q10 equal and mean?

Answer 13

For every 10 degrees the temperature increases the rate of reaction doubles

Question 14

How does temperature affect enzyme activity?

Answer 14

It increases the kinetic energy of the particles.Causes the particles to have more frequent successful collisions. Leads to an increase in rate of reaction

Question 15

What is optimum temperature?

Answer 15

The temperature at which the enzyme has the highest rate of activity. Animals tend to have an optimum of 40 degrees

Question 16

What happens if the enzyme temperature is too high?

Answer 16

Bonds holding the proteins break due to vibration. The breaking of the bonds causes the shape to change which means it has denatured

Question 17

What happens to enzymes in extreme temperatures?

Answer 17

Cells adapt to extremely cold or hot temperatures. Enzymes adapted to the cold have flexible structures making them less stable. Thermophiles (hot temp enzymes) are more stable and have hydrogen and sulphur bridges to strengthen bonds

Question 18

How does pH affect enzyme reactions?

Answer 18

A change in pH refers to a change in hydrogen ion concentration. The active site will only be in the right shape at certain hydrogen concentration. If the pH goes above optimum then the active site alters shape

Question 19

What happens to the enzyme physically with too much pH?

Answer 19

Structure is irreversibly altered. Active site is no longer complementary. Hydrogen ions interact with polar and charged R-groups. The more hydrogen ions present the less R-groups are available to interact so so bonds break.

Question 20

What happens if higher substrate concentration?

Answer 20

Increased number of substrate particles leads to higher collision rate with the active site and the enzyme making more enzyme-substrate complexes.

Question 21

What happens if higher enzyme concentration?

Answer 21

This increases the number of available active sites in a particular area leading to the formation of enzyme-substrate complexes at a faster rate

Question 22

What is an inhibitor?

Answer 22

Molecules that prevent enzymes from carrying out the normal function of a catalysis. Two types competitive and non-competitive

Question 23

How do competitive inhibitors work?

Answer 23

A molecule that has a similar shape to the substrate and can fit in the active site of an enzyme. This blocks the substrate from entering the active site preventing the enzyme from catalysing the reaction.

Question 24

What is a prosthetic group?

Answer 24

A cofactor that permanently bind to enzyme protein in order to activate them

Question 25

What does zinc do as a prosthetic group?

Answer 25

Inorganic and important part of the structure carbonic anhydrase and necessary for the metabolism of carbon dioxide

Question 26

what is an organic cofactor called?

Answer 26

A coenzyme

Question 27

What do coenzymes do?

Answer 27

Temporarily bind to enzyme active site and make it more complementary for the substrate

Question 28

How are inorganic cofactors obtained?

Answer 28

A mineral diet, for example: iron, calcium and chloride

Question 29

What is an inactive enzyme called?

Answer 29

Apoenzyme and an active one is holoenzyme

Question 30

What is end product inhibition?

Answer 30

Occurs when the product of an enzyme reacts as an an inhibitor in the enzyme that produces it. A negative feedback system. ATP is an example of this