2.1 - Generation of genetic diversity

Question 1

what is a mutation?

Answer 1

changes to base sequence in DNA

Question 2

how do mutations arise during DNA replication?

Answer 2

polymerase not perfect, sometimes incorrect base incorporated

Question 3

How is error rate reduced in DNA replication? (2)

Answer 3

1. polymerase have proofreading region
2. mismatch repair

Question 4

how have successful organisms evolved to repair their DNA?

Answer 4

efficiently but not too efficiently, leaving enough genetic variability on which natural selection can act

Question 5

What are purine and pyrimidine bases?

Answer 5

Purine - Adenine/Guanine
Pyrimidine - Cytosine/Thymine

Question 6

what is a transition mutation?

Answer 6

Purine/pyrimidine base replaced by another base of same class

Question 7

what is a transversion mutation?

Answer 7

Purine replaced by pyrimidine or vice versa

Question 8

What are the 3 types of mutations within genes? (3)

Answer 8

1. Silent mutation
2. Nonsense mutation
3. Missense mutation

Question 9

Describe silent mutations

Answer 9

Different base recruited that has impacted mRNA but no change to amino acid

Question 10

What is a silent mutation caused by?

Answer 10

Degeneracy - lots of different codons produce same amino acid

Question 11

describe nonsense mutations (2)

Answer 11

1. Different base recruited that gives codon that doesn’t recruit amino acid
2. stops protein production

Question 12

describe missense mutations (2)

Answer 12

1. change in DNA results in change of codon meaning different amino acid produced
2. sometimes protein can still function

Question 13

missense mutation nomenclature (3)

Answer 13

1. 1st letter - previous amino acid
2. number - amino acid position
3. 2nd letter - new amino acid

Question 14

what is the effect of frameshift mutations on protein production? (2)

Answer 14

• greater effect than substitution mutations
• often abolishes protein production

Question 15

where to frameshift mutations often occur?

Answer 15

tumor supressor genes

Question 16

Describe deletion (2)

Answer 16

• frameshift mutation
• removes at least 1 nucleotide from gene

Question 17

describe insertion

Answer 17

adds 1 or more nucleotides to gene

Question 18

how is evolutionary relatedness measured?

Answer 18

sequence similarity

Question 19

what genetic sequences are conserved?

Answer 19

sequences with vital functions

Question 20

example of a good mutation

Answer 20

• 35bp deletion in CCR5 gene
• confers resistance to HIV

Question 21

What are the 2 sources of genetic diversity? (2)

Answer 21

1. Mutation
2. Chromosomal changes

Question 22

When can chromosomal changes occur? (2)

Answer 22

1. Meiosis
2. viral integration

Question 23

what is a positive of genome instability?

Answer 23

major driver of evolution - provides variation on which natural selection can act

Question 24

karyotypic variation

Answer 24

more chromosomes doesn’t mean more genes

Question 25

how are amino acids grouped?

Answer 25

charge of R group

Question 26

what is a codon?

Answer 26

sequence of 3 nucleotides