Mutations

Question 1

What is the definition of a mutation?

Answer 1

Any alteration to the genetic material (DNA or RNA) that produces a heritable change in the nucleotide sequence

Question 2

What are not mutations? (2)

Answer 2

1. Chemical damage/modifications to DNA that’s not inherited

2. Genetic recombination involving homologous chromosome pairs

Question 3

What are the 3 large-scale change mutations?

Answer 3

1. Chromosomal aberrations
2. Genome rearrangements
3. Changes in chromosome number (aneuploidy)

Question 4

What are the 4 types of chromosomal aberrations and what is special about them?

Answer 4

Deletions
Duplications
Insertions
Inversions

Can be seen under a microscope

Question 5

How do genome rearrangements occur? (2)

Answer 5

Re-distribution of genetic material between chromosomes

Arise from chromosome breakage (translocation form one to another)

Question 6

How do changes in chromosome number occur?

Answer 6

Arise from mistakes in chromosome segregation at cell division - Down’s syndrome
Many are lethal

Question 7

What are the 5 types of localised change mutations?

Answer 7

1. Point mutations (transition or transversion)
2. Deletion, insertion (loss or gain of a BP)
3. Duplication (sequence is repeated)
4. Inversion (sequence is inverted)
5. Transposition (translocation of one DNA to another location)

Question 8

What is the definition of a point mutation?

Answer 8

A mutation that results in the substitution of one base pair for a different base pair

Question 9

What is the definition of a transition mutation?

Answer 9

Changes a purine for a purine (G to A) or a pyrimidine for a pyrimidine (C to T)

Question 10

What is the definition of a transversion mutation?

Answer 10

Changes a purine for a pyrimidine or a pyrimidine for a purine (GC to AT)

Question 11

What are the 3 classes of point mutations?

Answer 11

Silent
Missense
Nonsense

Question 12

How does a frameshift occur?

Answer 12

Alteration of the reading frame due to an insertion/deletion of a nucleotide

Question 13

On an OFR graph of nucleotides, what represents stop codons and what represents start codons?

Answer 13

Stop: vertical bar
Start: ticks

Question 14

What can we create to compare base sequences?

Answer 14

Phylogenetic tree

Question 15

What are the effect of point mutations on protein produced? (3)

Answer 15

No effect: - samesense and missense
Change of function: missense, small deletions
Loss of function: missense, nonsense and frameshift

Question 16

What is the effect of point mutations on the organism? (4)

Answer 16

1. No observable effect
2. Loss of function
3. Altered phenotype
4. Genetic disease

Question 17

What is an example of mutations in organisms? (2)

Answer 17

Haploids such a yeast and bacteria

Diploids: - mutation prevents gene product syntheses; Mutation alters gene product

Question 18

What are the 3 types of mutant genotype classification?

Answer 18

1. wild type - recessive (masked)
2. Mutant - dominant
3. intermediate - co-dominant

Question 19

What is reversion and how can it get worse?

Answer 19

Reversion is when a purine or pyrimidine is swapped

It can get worse by reversion happening and then a frameshift occurring too