U1:KA6 - Mutations

Question 1

What is a mutation?

Answer 1

A mutation is a random change to genetic material they do not happen very frequently

Question 2

What can mutations result in?

Answer 2

They can result in no protein or an altered protein being synthesised

Question 3

What is a single gene mutation?

Answer 3

A mutation which only affects a few bases

Question 4

What is a chromosome structure mutation?

Answer 4

A mutation which can affect the structure of one or more chromosomes

Question 5

What do single gene mutations involve?

Answer 5

They involve a change in one of the base pairs in the DNA sequence of a single gene

Question 6

What are the 3 different types of point mutations?

Answer 6

Substitution, insertion, deletion

Question 7

What happens in a substitution mutation?

Answer 7

One nucleotide is substituted for another within a DNA sequence and a wrong amino acid may be inserted into a protein

Question 8

What happens in an insertion mutation?

Answer 8

A certain number of nucleotides are inserted into a DNA sequence and all subsequent triplets are read incorrectly

Question 9

What happens in a deletion mutation?

Answer 9

Deletion means a certain number of nucleotides are removed from the DNA sequence and all the subsequent triplets are read incorrectly

Question 10

What are the 3 different effects of substitutions?

Answer 10

Silence, missense, nonsense

Question 11

What does silence mean?

Answer 11

Has no effect on the protein sequence

Question 12

What does missense mean?

Answer 12

Replacing one amino acid codon with another (non functioning protein/little effect)

Question 13

What does nonsense mean?

Answer 13

Replacing an amino acid codon with a premature stop codon - no amino acids made an process stops (shorter protein)

Question 14

What can mutations at splice sites result in?

Answer 14

They can result in the inclusion of an intron in a mature mRNA which should not be, and may result in a non-functional protein

Question 15

What are 4 examples of mutations?

Answer 15

Sickle cell anaemia, cystic fibrosis, duchenne muscular dystrophy, phenylketonuria

Question 16

What is sickle cell anaemia and what is it caused by?

Answer 16

It is caused by a single substitution mutation on the haemoglobin gene, causing changes in the shape of red blood cells, thus reduced oxygen flow in the body.

Question 17

What is cystic fibrosis and what is it caused by?

Answer 17

It is caused by a 3 base deletion, removing a codon and causing a frame shift to occur results in thick mucus in respiratory system

Question 18

What is duchenne muscular dystrophy and what is it cause by?

Answer 18

It is caused by several deletions within a gene, causing a frame shift mutation resulting in no dystrophin protein being made with no protein, muscles are weak and development is affected

Question 19

What is phenylketonuria and what is it cause by?

Answer 19

It is caused by a deletion, resulting in a frame shift and earlier stop codon the resulting protein in non-functional and results in phenylalanine to build up to a toxic level, affecting brain development, treatable if caught early

Question 20

What do chromosome mutations arise through?

Answer 20

Changes in the structure of chromosomes

Question 21

When can changes in the structure of chromosomes occur?

Answer 21

They can occur when a chromosome breaks the cell then attempts to repair the break, but in doing so may not restore the chromosome to its original structure.

Question 22

What does duplication allow?

Answer 22

It allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce protein