Unit 1 Key area 6

Question 1

Define the term “Mutation”?

Answer 1

A mutation is a change in DNA that result in no proteins or and “altered” protein being “synthesised”.

Question 2

What are the different types of single gene mutations?

Answer 2

• Insertion
• Deletion
• Substitution

Question 3

Give an account of the different types of mutations that can be caused by a substitution.

Answer 3

• Missense mutations occur when one nucleotide is changed for another. This can cause a minor change in the structure of a protein or result in the production of a non-functional protein.
• Nonsense mutations occur when a premature stop codon is created as a result of a mutation. This premature stop codon will cause the protein being produced to be shorter which may result in a non-functional protein being produced.
• Splice site mutations can occur in which a mutation at the splice site can cause certain introns to be retained in the mature mRNA transcript and other exons to be left out of the mature mRNA transcript. This results in the production of a protein with an altered structure and function.

Question 4

What type of mutations are caused by an insertion or deletion mutation?

Answer 4

Insertion or deletion mutations cause a frame-shift mutation, which cause all of the codons and all of the amino acids after the point of mutation to be altered. This type of mutation has a major impact on the protein produced.

Question 5

Name the different types of chromosome structure mutations?

Answer 5

• Duplication
• Translocation
• Inversion
• Deletion

Question 6

What happens during an duplication mutation?

Answer 6

In a duplication mutation a section of a chromosome is added to the chromosome from its “homologous partner”

Question 7

What happens during a deletion mutation?

Answer 7

In a deletion mutation a section of a chromosome will be removed

Question 8

What happens during an Inversion mutation?

Answer 8

In an inversion mutation a section of a chromosome will be inverted 180 degrees.

Question 9

What happens during a translocation mutation?

Answer 9

During a translocation mutation a section of a chromosome is added to the chromosome not from its homologous partner.

Question 10

What is the end result of most chromosome structure mutations?

Answer 10

Due to the substantial changes made to the organism’s DNA the chromosome structure mutations are often fatal.

Question 11

Explain why duplication mutations can be advantageous for an organism?

Answer 11

As duplication allows for potentially beneficial mutations to occur in the duplicated gene while the original gene can still be expressed to produce the proteins required.