Unit 1 Topic 6

Question 1

What are three types of single gene mutations?

Answer 1

substitution
insertion
deletion

Question 2

What is a substitution mutation?

Answer 2

a substitution mutation means that one nucleotide is substituted for another and an incorrect amino acid may be inserted into a protein

Question 3

Give an example of a major problem that can be the result of a substitution mutation

Answer 3

sickle cell anaemia
however, usually these changes are minor

Question 4

What is an insertion mutation?

Answer 4

the addition of one or more nucleotides into a section of DNA

Question 5

What does an insertion lead to?

Answer 5

all subsequent triplets are read incorrectly therefore the protein made is likely to have many different amino acids and may not work at all

Question 6

What is a deletion mutation?

Answer 6

a deletion mutation refers to the removal of one or more nucleotides from the DNA

Question 7

What is the result of a deletion mutation?

Answer 7

a deletion mutation alters the pattern of base triplets in the DNA. This means that deletions of one or two nucleotides are likely to cause drastic changes to a protein

Question 8

What can both insertion and deletion mutations be known as?

Answer 8

frame shift mutations

Question 9

What does the effect of a mutation depend on?

Answer 9

its type and location

Question 10

What happens to a protein if it does not have the correct sequence of amino acids?

Answer 10

it doesn’t function properly

Question 11

What are three effects of a substitution mutation?

Answer 11

missense
nonsense
splice site mutations

Question 12

what is a missense mutation?

Answer 12

a missense mutation results in a single incorrect amino acid being inserted into a protein

Question 13

how bad is the effect of a missense mutation?

Answer 13

the effect the altered amino acid has on the function of the protein will vary depending on its location and chemical properties. this can result in abnormally short protein which may not function properly

Question 14

what is a splice site mutation

Answer 14

splice-site mutations result in some introns being retained and/or some exams not being included in the mature transcript and may result in a non-functional protein.

Question 15

What can splice site mutations alter?

Answer 15

post-transcriptional processing

Question 16

What do nucleotide insertions and deletions result in?

Answer 16

frame-shift mutations

Question 17

What usually has a greater effect and why:
insertions and deletions or substitutions

Answer 17

insertions and deletions because they result in frame-shift mutations

Question 18

what is mRNA read in?

Answer 18

groups of three
(codons)

Question 19

what makes an insertion/deletion mutation have a worse effect?

Answer 19

if the mutation occurs early in the sequence as more codons will be changed

Question 20

what also happens as a result from frameshift mutations?

Answer 20

the stop sequence will become misplaced which could result in the polypeptide being either too long or too short

Question 21

what can substitution cause which would make the polypeptide too short?

Answer 21

a premature stop codon

Question 22

what are four types of chromosome structure mutations?

Answer 22

translocation
deletion
duplication
inversion

Question 23

what is a translocation mutation?

Answer 23

a section of a chromosome is added to another chromosome, not it’s homologous partner

Question 24

what is a deletion mutation in chromosome structure mutations?

Answer 24

a section of a chromosome is removed

Question 25

what is a duplication chromosome?

Answer 25

a section of a chromosome is added from its homologous partner

Question 26

what is an inversion mutation?

Answer 26

where a section of chromosome is reversed

Question 27

why are mutations important?

Answer 27

mutations provide new variation. mutations bring about new variation by the production of new allele. without mutations there would be no new variation

Question 28

why is the duplication of an entire gene useful?

Answer 28

the second copy of the gene can become altered and provide new DNA sequences. this gene duplication is thought to be an important driving force in evolution