Session 15: Mutations

Question 1

What is a mutation?

Answer 1

A change in the DNA sequence

Question 2

A mutation can arise from what?

Answer 2

DNA replication errors made during cell division
Exposure to ionising radiation
Exposure to chemicals
Infection by viruses

Question 3

What is the name given to mutations that occur in the eggs or sperm, affect all cells in the body and can be passed on to offspring?

Answer 3

Germ line mutations

Question 4

What is the name given to a mutation that occurs in a boy cell and is not passed onto offspring

Answer 4

Somatic mutation

Question 5

Why do RNA polymerases not need to proofread like DNA polymerases?

Answer 5

The cell will be making multiple copies of the RNA, it is unlikely to make the same mistake again i exactly the same place
RNAs are quickly degraded so the bad copy will be removed
RNAs are not inherited molecules and won’t be passed down from generation to generation (Not as consequential)

Question 6

What is the role of the mitochondria?

Answer 6

To produce energy

Question 7

Mitochondria DNA can suffer from mutations in the germ line or somatic mutations?

Answer 7

Both

Question 8

Germ line mutations in the gene can be what three things?

Answer 8

Substitution
Insertion
Deletion

Question 9

Which gene mutations in the germ line leads to a frame shift?

Answer 9

Insertion and deletion

Question 10

Germ line mutations in the chromosome can result from what?

Answer 10

Structural: 
Deletion 
Duplication 
Inversion 
Translocation 

Number:
Non-disjunction

Question 11

What is the chromosome and chromatid number at meiosis I?

Answer 11

Chromsomes: 46
Chromatid: 92 (genetic material is doubled)

Question 12

What is the chromosome and chromatid number at meiosis II?

Answer 12

(Both halved)
Chromosome: 23
Chromatid: 46

Question 13

What is the chromosome and chromatid number at the end of Meiosis?

Answer 13

Chromosome: 23
Chromatid: 23

Question 14

Can mitosis produce a chromosomal mutation?

Answer 14

Yes, errors may occur during metaphase when the chromosomes align at the metaphase plate

Question 15

What could happen if there was a mitotic chromosomal mutation in one of the 2 cells at the 2 cells stage or 1 of the 4 cells at the 4 cell stage etc. during early embryogenesis?

Answer 15

Result in a mosaic individual: an individual with two or more populations of cells with different genotypes

Question 16

What are the possible outcomes if a very early embryo was exposed to radiation?

Answer 16

Death/aborted
Teterogenesis
Increased risk of cancer when born

Question 17

What features allow a germ cell mutation to be inheritable?

Answer 17

Not be lethal to the gamete
Not impair gamete function
Not be lethal at fertilisation
Allow the production of a viable adult with normal reproductive capacity

Question 18

Why do primordial germ cells in males only start to differentiate into spermatazoa at puberty?

Answer 18

They are only needed when oocytes are available to fertilise