Enzymes

Question 1

Ends of a DNA fragment with no overhanging bases after being cut by an endonuclease

Answer 1

Blunt Ends

Question 2

Ends of a DNA fragment with overhanging bases after being cut by an endonuclease

Answer 2

Sticky Ends

Question 3

What is the purpose of an endonuclease?

Answer 3

To cleave a segment of DNA

Question 4

Outline how an endonuclease can be regulated within a biochemical reaction.

Answer 4

• Regulation may be achieved through a competitive or non-competitive inhibitor
• DNA cleavage only occurs at set recognition site

Question 5

Enzyme involved in synthesizing nucleic acids

Answer 5

Polymerase

Question 6

An enzyme that catalyses the joining of two double-stranded DNA fragments

Answer 6

Ligase

Question 7

Predict whether a DNA strand would be repaired by RNA Ligase

Answer 7

• No
• The RNA Ligase would not be complimentary in terms of shape to the DNA strand so no interaction would occur

Question 8

Outline the action of a non-competitive inhibitor

Answer 8

• The non-competitive inhibitor binds to the allosteric site of an enzyme
• This causes a conformational change to the shape of the active site
• As a result the substrate will no longer be able to bind to active site

Question 9

Explain a mechanism by which a plant may overcome the action of a competitive inhibitor targeting the Rubisco enzyme

Answer 9

• The primary substrate for Rubisco is Carbon Dioxide
• A competitive inhibitor competes with the substrate to bind to the active site of Rubisco
• By opening their stomata plant introduce more substrate to the cellular environment to outcompete the inhibitor and bind more Carbon Dioxide to the active site of Rubisco