Module 8- Module 8 - Alteration of the sequence of bases in DNA can alter the structure of proteins

Question 1

What is a mutation?

Answer 1

This is when there is a change to the base nucleotide sequence of DNA

Question 2

What is substitution deletion?

Answer 2

This is when one or more bases is swapped for another

Question 3

What is a deletion mutation?

Answer 3

This is when one or more bases are removed causing a frameshift

Question 4

What is an addition mutation?

Answer 4

This is when one or more bases are added causing a frameshift

Question 5

What is a duplication mutation?

Answer 5

One or more bases are repeated

Question 6

What is an inversion mutation?

Answer 6

The DNA of a single gene is cut in 2 place. The cut portion is inverted 180degrees then rejoined to the same place within the gene
Frequently result in a non- functional protein

Question 7

What is a translocation mutation?

Answer 7

A sequence of bases which is moved from one location in the genome to another. This can be a movement within the same chromosome or a movement to a different chromosome

Question 8

Why do some mutations not lead to a change in the amino acid sequence?

Answer 8

Some amino acids are degenerate meaning that it doesn’t always cause a evident change

Question 9

What mutations will have the least impact on an amino acid sequence?

Answer 9

Substitution and inversion

Question 10

What are mutagenic agents?

Answer 10

These are factors that increase the likelihood of a mutation happening

Question 11

What are the 4 main examples of a mutagenic agent?

Answer 11

• Ultraviolet radiation
• Ionising radiation
• Chemicals
• Viruses

Question 12

What are the 3 ways mutagenic agents can increase the rate of mutations?

Answer 12

• Acting as a base
• Altering bases
• Changing the structure of DNA

Question 13

How does a mutation of human genes that code for tumour suppressor genes cause cancer?

Answer 13

A mutation in a tumour suppressor proteins could cause a change in the DNA base sequence resulting in a change in the tertiary structure of the tumour suppressor proteins resulting in uncontrolled cell division

Question 14

3 marks

Explain how a single base substitution causes a change in the structure of this polypeptide.
Do not include details of transcription and translation in your answer.

Answer 14

1. Change in sequence of amino acids
2. Change in hydrogen/ionic/disulfide bonds
3. Alters tertiary structure