enzymes

Question 1

What forms when substrate enters the active site of an enzyme?

Answer 1

An enzyme-substrate complex forms.

Question 2

What happens after the enzyme-substrate complex forms?

Answer 2

An enzyme-product complex forms, and the product leaves the active site.

Question 3

What is the lock and key hypothesis?

Answer 3

The shape of the substrate’s active site and the shape of the enzyme are complementary, making the enzyme specific.

Question 4

What is the induced fit model?

Answer 4

The enzyme’s active site changes shape to accommodate the substrate once it binds.

Question 5

How does temperature affect enzyme activity?

Answer 5

Higher temperatures increase kinetic energy, leading to more successful collisions and enzyme-substrate complexes. Lower temperatures decrease kinetic energy, resulting in fewer complexes.

Question 6

What is the optimum temperature for enzymes?

Answer 6

Enzymes have an optimum temperature, and small increases above this can affect the bonds in the tertiary structure, altering the active site.

Question 7

What happens to enzymes at high temperatures?

Answer 7

High temperatures can result in denaturation of the enzyme, which is irreversible.

Question 8

What role do cofactors and prosthetic groups play in enzyme activity?

Answer 8

They bind to the enzyme temporarily to change the shape of the active site, increasing the likelihood of substrate binding.

Question 9

What are enzymes known as?

Answer 9

Enzymes are known as biological catalysts.

Question 10

What do enzymes do in metabolic pathways?

Answer 10

They alter the rate of chemical reactions by lowering the activation energy.

Question 11

What is an extracellular enzyme?

Answer 11

An enzyme that works outside of cells.

Question 12

How does an enzyme break down a substrate?

Answer 12

The substrate fits into the active site via the induced fit model, forming an enzyme-substrate complex that destabilizes the substrate’s bonds.

Question 13

Can an enzyme break down different compounds?

Answer 13

Yes, if they are similar in shape and can fit into the active site.

Question 14

Why are vitamins and minerals needed in small amounts?

Answer 14

They act as cofactors and can be recycled in the body.

Question 15

How can you test cofactor action?

Answer 15

• You can test cofactor action by carry out the reaction with and without the cofactor, and testing at least 3 different concentrations of cofactor, and also running one reaction without the cofactor to act as a control.
• You would keep the enzyme and substrate concentration constant, and also keep the temperature and pH at optimum for all trials and would measure the rate of product production at set intervals over a set time period (i.e: one hour) for each trial.
• You would do repeats of each trial for reliability’s sake

Question 16

What happens at optimum temperature for enzyme activity?

Answer 16

Enzyme and substrate molecules have high kinetic energy, leading to frequent collisions and maximum product production.

Question 17

What is a better method for sourcing enzymes from plants?

Answer 17

Use a single source and thoroughly mix and purify to ensure exact concentration.

Question 18

What occurs at temperatures higher than optimum?

Answer 18

Enzyme molecules vibrate excessively, breaking bonds and altering the tertiary structure, leading to denaturation.

Question 19

Why are different enzymes involved in digestion?

Answer 19

Different stages of digestion have substrates of different shapes, requiring specific enzymes.

Question 20

What happens to enzyme activity at extreme pH levels?

Answer 20

Enzyme activity falls to zero as the charge of the active site changes, leading to denaturation.

Question 21

How do competitive inhibitors work?

Answer 21

They fit into the active site, blocking it as they are similar in shape to the substrate.

Question 22

What happens when substrate concentration increases?

Answer 22

More substrate molecules enter the active site, forming more enzyme-substrate complexes.

Question 23

What effect does a competitive inhibitor have on reaction rate?

Answer 23

It reduces the number of available active sites, but increasing substrate concentration can increase the reaction rate.

Question 24

Why might the initial rate of an enzyme-controlled reaction be faster?

Answer 24

Because the concentration of substrate is higher at the start, leading to more active sites being occupied.

Question 25

How do non-competitive inhibitors affect enzymes?

Answer 25

They bind to an allosteric site, changing the shape of the active site so the substrate no longer fits.

Question 26

What is an example of a non-competitive inhibitor?

Answer 26

An inhibitor that prevents mRNA production, affecting vital protein synthesis.

Question 27

How do chloride ions act as cofactors?

Answer 27

They bind to the enzyme, facilitating the formation of the enzyme-substrate complex.

Question 28

Why are the induced fit and lock and key hypotheses considered models?

Answer 28

They are simple representations of how the enzyme-substrate interaction works.

Question 29

Why do scientists prefer the induced fit model?

Answer 29

It is supported by more evidence than the lock and key model.

Question 30

What happens to enzyme-driven reactions below optimum temperature?

Answer 30

They occur more slowly due to lower kinetic energy and fewer collisions.

Question 31

How can a more flexible enzyme structure benefit its function?

Answer 31

It allows easier substrate entry and more bond formation due to greater surface area.

Question 32

What causes differences in proteins?

Answer 32

Differences arise from varying amino acid sequences, folding patterns, and bonding interactions.