20.1: Gene mutations

Question 1

Mutation

Answer 1

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

Question 2

Gene mutation

Answer 2

Any change to 1 or more of the nucleotide bases or any rearrangement of the bases in DNA.

Question 3

Substitution of bases

Answer 3

Gene mutation when a nucleotide in a section of DNA is replaced by another nucleotide that has a different base.

Question 4

How many possible consequence of substitution of bases

Answer 4

3

Question 5

Effect of formation of a stop codon in substitution of bases

Answer 5

Causes polypeptide production to be stopped early.

Causes the final protein to be significantly different and unable to perform its normal function.

Question 6

Effect of formation of a codon for a different amino acid

Answer 6

Meaning that the structure of the polypeptide produced would differ in 1 amino acid.
This may cause the protein to differ in shape and not function properly.

Question 7

Effects of formation of a different codon but which codes for the same amino acid

Answer 7

(Due to the genetic code being degenerate)

No effect on the polypeptide produced and no overall effect.

Question 8

Deletion of bases

Answer 8

A base is deleted

Question 9

Frame shift in deletion

Answer 9

Created by deletion of 1 base and the reading frame that contains 3 letters has been shifted to the left by 1.

Question 10

Possible effect of deletion

Answer 10

Alteration of phenotype

Question 11

6 types of gene mutation

Answer 11

substitution
addition
deletion
duplication
inversion
translocation

Question 12

Addition of bases

Answer 12

An extra base is inserted into the sequence.

Question 13

Why won’t there be a frame shift in an addition mutation and possible effect

Answer 13

if any multiple of 3 bases are added there won’t be a frame shift but there could be a different polypeptide produced.

Question 14

Duplication of bases

Answer 14

One or more bases are repeated, causing a frame shift to the right

Question 15

Inversion of bases

Answer 15

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

Question 16

Inverse order

Answer 16

back to front

Question 17

Translocation of bases

Answer 17

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

Question 18

What can translocation of bases lead to

Answer 18

a different phenotype can cause development of some forms of cancer and reduced fertility

Question 19

How do mutations arise

Answer 19

spontaneously

Question 20

What type of occurrences are mutations

Answer 20

random occurrences but occur with a predictable frequency

Question 21

Mutagenic agents

Answer 21

outside factors that increase the basic mutation rate

Question 22

Another word form mutagenic agents

Answer 22

mutagens

Question 23

Two examples of mutagenic agents

Answer 23

high energy ionising radiation

chemicals

Question 24

High energy ionising radiation

Answer 24

for example alpha and beta particles as well as short wavelength radiation such as x-rays and ultraviolet light can disrupt the structure of DNA

Question 25

Chemicals as mutagenic agents

Answer 25

Such as NO2 may later the structure of DNA or interfere with transcription.