Enzymes

Question 1

What are enzymes?

Answer 1

Biological catalysts that speed up the rate of metabolic reactions

Question 2

What type of reactions determine structure and function of organisms?

Answer 2

Intracellular and extracellular which determines the structure and function from cellular to whole organism level

Question 3

What type of polymer are enzymes?

Answer 3

Proteins

Question 4

Give the structure of an enzyme

Answer 4

Enzymes have a specific 3D tertiary shape and active site

Question 5

What is the role of the active site?

Answer 5

To bind to complimentary substrate molecules to form enzyme-substrate complexes

Question 6

Give the three way word that gives at least one mark on enzymes

Answer 6

Enzyme- substrate complexes

Question 7

Define Activation energy

Answer 7

The amount of energy required to speed up the rate of reaction

Question 8

How does enzymes relate to activation energy?

Answer 8

Enzymes lower the activation energy of the reaction it catalyses

Question 9

Why are enzymes highly specific

Answer 9

Because of their tertiary structure

Question 10

What do enzymes combine to?

Answer 10

Complimentary substrates to form enzyme-substrate complexes

Question 11

What type of proteins are enzymes

Answer 11

Globular proteins

Question 12

Describe the ‘lock and key’ model

Answer 12

• The substrate fits into the active site like a key fits into a lock
• Active site is rigid

Question 13

Describe the ‘induced fit’ model

Answer 13

• The active site is flexible
• When substrate binds to active site, it changes its shape slightly to mound itself around the substrate

Question 14

What determines the active site shape?

Answer 14

The tertiary structure

Question 15

Different enzymes have….?

Answer 15

Different tertiary structures

Question 16

What factor can change the structure of enzyme produced?

Answer 16

Gene/ mutation in the primary structure

Question 17

What happens if the structure of enzyme is altered in any way?

Answer 17

It changes the shape of the active site and enzyme-substrate complexes can’t be formed

Question 18

List 3 factors affecting enzyme activity

Answer 18

• High/low Temperature
• pH
• Enzyme/substrate concentration

Question 19

How does an increase in temperature affect the rate of reaction?

Answer 19

It increases the rate of reaction

Question 20

How does temperature affect rate of reaction?

Answer 20

It increases the kinetic energy of enzyme and substrate molecules which lead to more collisions between enzyme and substrate molecules

Question 21

An increase leads to what?

Answer 21

More enzyme-substrate complexes binding

Question 22

At what temperature do enzymes become denatured

Answer 22

Optimum temperature/40C

Question 23

What happens if enzymes hit optimum Temperature (5)

Answer 23

• High amount of energy causes bonds to break
• Changes 3D structure
• Changes shape of active site
• Enzymes become denatured
• Enzyme substrate complexes can’t be formed

Question 24

Draw a graph on Temperature effect on enzyme-controlled reactions

Answer 24

Search if you got the answer right

Question 25

How does pH affect rate of enzyme activity? (5)

Answer 25

•Above/below pH can break hydrogen and ionic bonds that hold the tertiary structure
• It makes the enzyme change shape
• Active site looses its shape
• Enzyme becomes denatured
•Enzyme-substrate complexes can’t be formed

Question 26

How does substrate concentration affect rate of reaction?

Answer 26

• Increasing rate of substrate concentration increases rate of reaction
• More enzymes will bind to form enzyme-substrate complexes
• However, beyond a certain point, SATURATION will occur
• This is when there are no more enzyme molecules to catalyze substrate molecules

Question 27

How does enzyme concentration affect rate of reaction (4)

Answer 27

• Increasing enzyme molecules will increase the rate of reaction
• more substrates will bind to enzyme active site
• More enzyme-substrate complexes will be formed
• However beyond a certain saturation, rate will no longer be increased because all substrate molecules have been binded to enzyme active site

Question 28

Characteristics and functions of competitive inhibitors (4)

Answer 28

• They have a similar shape to substrate molecules
• They bind to the active site of enzymes to block substrate molecules, however no reaction happens
• They block so substrate molecules can’t fit in
• Increasing the substrate concentration will increase the rate of reaction. Competitive inhibitors can be cancelled by this because substrate molecules will reach the active site quicker
• Prevents complimentary base pairing

Question 29

Characteristics of Non-competitive inhibitors and functions (4)

Answer 29

• They bind away from the active site
• Causes the shape of the enzyme to change so substrate molecules cannot fit in
• Thus changes the shape of the active site
• Increasing the substrate concentration will not increase the rate of reaction. Enzyme activity will still be inhibited

Question 30

Describe 1 similarity and 1 difference between lock and key and induced fit model

Answer 30

• Substrate fits/ binds to active site
• Active site changes shape but does not change in lock and key