Gene Expression- Mutations

Question 1

What is a mutation?

Answer 1

Any change to the base sequence

Question 2

How can mutations be caused?

Answer 2

By errors during DNA replication

Question 3

How can the rate of mutation be increased?

Answer 3

By mutagenic agents

Question 4

What are the types of mutations that can occur?

Answer 4

Substitution, deletion, addition, duplication, inversion and translocation

Question 5

What is a substitution mutation?

Answer 5

One or more bases are swapped for another

Question 6

What is a deletion mutation?

Answer 6

One or more bases are removed

Question 7

What is an addition mutation?

Answer 7

One or more bases are added

Question 8

What is a duplication mutation?

Answer 8

One or more bases are repeated

Question 9

What is an inversion mutation?

Answer 9

A sequence of bases is reversed

Question 10

What is a translocation mutation?

Answer 10

A sequence of bases is moved from one location in the genome to another- could be a movement within the same chromosome or movement to a different chromosome

Question 11

Why is the order of DNA bases in a gene important?

Answer 11

Determines the sequence of amino acids in a particular polypeptide

Question 12

What could happen if a mutation occurs?

Answer 12

The sequence of amino acids in the polypeptide that it codes for could be changed

Question 13

What might a change in amino acid sequence of a polypeptide cause?

Answer 13

A change in tertiary structure of the protein which could mean it doesn’t work properly

Question 14

What are genetic disorders?

Answer 14

Inherited disorders caused by abnormal genes or chromosomes

Question 15

What can some mutations increase the likelihood of?

Answer 15

Developing certain cancers

Question 16

What does the degenerate nature of the genetic code mean?

Answer 16

Not all types of mutation will always result in a change to the amino acid sequence of the polypeptide

Question 17

Which mutations will almost always change the amino acid sequence of a polypeptide?

Answer 17

Additions, duplications and deletions because these mutations change the number of bases in the DNA code

Question 18

What does changing the number of bases in the DNA code cause?

Answer 18

A shift (frameshift) in the base triplets that follow so the triplet code is read in a different way

Question 19

What are some mutagenic agents?

Answer 19

Ultraviolet radiation, ionising radiation, chemicals and viruses

Question 20

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

Answer 20

1. Acting as a base- chemicals called base analogs can substitute for a base during DNA replication, changing base sequence for new DNA
2. Altering bases- some chemicals can delete or alter bases
3. Changing structure of DNA- some types of radiation can change structure of DNA and cause problems in DNA replication