MCGB - Mutations

Question 1

What is a mutation?

Answer 1

A change in the DNA sequence.

Question 2

Give some things that can cause mutations.

Answer 2

DNA replication errors during cell division, exposure to ionising radiation/chemicals, infection by viruses

Question 3

What are germ-line mutations?

Answer 3

Mutations that occur in the eggs/sperm which affect all cells in body and can be passed on to offspring

Question 4

Is a somatic mutation passed on to offspring?

Answer 4

No, as these occur in body cells and are therefore not passed on.

Question 5

Why are RNA errors more common than DNA errors?

Answer 5

RNA polymerase don’t proofread

Question 6

Why is it not as bad to have a mistake in the RNA compared to the genome?

Answer 6

RNA is not passed on from generation to generation, but the genome is

Question 7

True or false - mitochondrial DNA is also prone to somatic mutations?

Answer 7

True - it has a limited ability to repair itself so mutations build up over time

Question 8

Why is it unlikely for a spontaneous mutation to cause an autosomal recessive disorder?

Answer 8

The individual must have suffered a spontaneous mutation of the same gene on both chromosomes

Question 9

What can be caused by duplicated chromosomes not pairing properly at the metaphase plate?

Answer 9

Anaphase lag (one cell has two copies of chromosome while other has none).

Question 10

What is a primordial follicle?

Answer 10

A primary oocyte surrounded by flattened epithelial cells.

Question 11

Why do primordial germ cells only start to differentiate into spermatozoa at puberty?

Answer 11

They are only needed when oocytes are available to fertilise.

Question 12

True or false - not many miscarriages are due to chromosomal abnormalities?

Answer 12

False - 75% of clinically recognised pregnancy loss is due to this

Question 13

Give some causes of somatic mutations.

Answer 13

Mutagens, radiation, viruses

Question 14

Are tumours more likely to be due to somatic or germ-line mutations?

Answer 14

Somatic

Question 15

Is the majority of radiation received by the UK population natural or artificial?

Answer 15

Natural - 50% comes from radon gas in the ground

Question 16

What are “transposable elements”?

Answer 16

Sequences of DNA known as “jumping genes” that move from one location in the genome to another.

Question 17

Which is the odd one out? Deletion, duplication, inversion, substitution, translocation, non-disjunction.

Answer 17

Non-disjunction - the rest are all mutations.

Question 18

What is a transition single nucleotide base?

Answer 18

When a base is swapped for another of the same type, so purine to purine or pyramidine to pyramidine

Question 19

What is a transversion single nucleotide change?

Answer 19

Change to a different type of base - purine to pyramidine or vice versa.

Question 20

What causes sickle cell anaemia?

Answer 20

Mutation is amino acid sequence - glu to val

Question 21

What is a missense mutation?

Answer 21

Single nucleotide change that changes the amino acid

Question 22

What is a silent/neutral/synonymous mutation?

Answer 22

A mutation that has no effect

Question 23

What is a nonsense mutation?

Answer 23

When a stop codon is created prematurely.

Question 24

Why does it often not matter if the is a mutation in DNA?

Answer 24

Because a large amount of DNA is non-coding