Q5: Gene mutations and their effects

Question 1

Mutation

Answer 1

Any change to the quantity or the structure of the DNA of an organism.

Question 2

Gene mutation

Answer 2

Any change to one or more of the nucleotide bases, or any rearrangement of the bases in DNA.

Question 3

Types of mutations

6

Answer 3

substitution
deletion
addition
duplication
inversion
translocation

Question 4

Substitution of bases

Answer 4

A mutation in which a nucleotide in a section of a DNA molecules is replaced by another nucleotide that has a different base.

Question 5

Consequences of a substitution mutation

3

Answer 5

1. Formation of a stop codon which is premature
2. Formation of a different codon for a different amino acid
3. Formation of a different which produces the same amino acid

Question 6

Deletion of base(s)

Answer 6

The loss of a single nucleotide base from a DNA sequence

Question 7

Deletion of bases frame shift direction

Answer 7

to the left

Question 8

Addition of bases

Answer 8

An extra base is inserted in the DNA sequence

Question 9

Addition of of bases frame shift direction

Answer 9

to the right

Question 10

Duplication of bases

Answer 10

One or more bases are repeated

Question 11

Duplication of bases frame shift direction

Answer 11

to the right

Question 12

Inversion of bases

Answer 12

A group of bases become separated from the DNA sequence and rejoin at the same position but in the inverse order

Question 13

Translocation of bases

Answer 13

A group of bases becomes separated from the DNA sequence of one chromosome and become inserted into the DNA sequence of a different chromosome

Question 14

Gene mutations can arise … during DNA replication

Answer 14

spontaneously

Question 15

Spontaneous mutations

Answer 15

Permanent changes in DNA that occur without any outside influence.

Question 16

Despite being random occurrences…

Answer 16

mutations occur with a predictable frequency

Question 17

Mutagenic agents/ mutagens

Answer 17

increase the basic mutation rate

Question 18

Mutagenic agents/ mutagens

2 types

Answer 18

chemicals

high energy ionising radiation

Question 19

High energy ionising radiation

as a mutagen

Answer 19

Alpha and beta particles and short length radiation can disrupt the structure of DNA.

Question 20

Short length radiation which can be a mutagen

Answer 20

x-rays and UV light

Question 21

Chemicals

as mutagens

Answer 21

Directly alter the structure of DNA or interfere with transcription.

Question 22

Example of chemical mutagen

Answer 22

nitrogen dioxide

Question 23

Benefit of mutations

Answer 23

produce genetic diversity

Question 24

Disadvantage of mutations

2

Answer 24

almost always harmful

produce an organism less well suited to its environment