Module 16: Mutations

Question 1

What are mutations?

Answer 1

Changes in the nucleotide sequence of DNA.

Question 2

Do mutations always cause disease?

Answer 2

No.
Some mutations have no effect on phenotype.

Question 3

What are germline mutations?

Answer 3

Mutations that occur in sex cells (sperm or egg) and are transmitted to the offspring.

Question 4

Are somatic cell mutations inherited between generations?

Answer 4

No.

Question 5

What are cancer-causing mutations?

Answer 5

Somatic cell mutations that interfere in cell cycle regulation.

Question 6

What is non-disjunction?

Answer 6

The failure of sister chromatids to separate properly during cell division.

Question 7

What are the 4 types of large-scale mutations?

Answer 7

1. Deletion.
2. Duplication.
3. Inversion.
4. Translocation.

Question 8

What are large-scale mutations?

Answer 8

Mutations involving the partial rearrangement or even non-disjunction of chromosomes.
Includes multiple genes.

Question 9

What would a large-scale mutations in a germ cell likely cause?

Answer 9

A miscarriage.

Question 10

What are small-scale mutations?

Answer 10

Mutations involving only one or a few base pairs.

Question 11

What are point mutations?

Answer 11

A mutation in a single nucleotide in a DNA sequence.

Question 12

What are the types of point mutations?

Answer 12

1. Substitution.
2. Insertion.
3. Deletion.

Question 13

What are silent mutations?

Answer 13

A mutation in the DNA sequence that has no observable effect on the produced protein.
e.g. a substituted nucleotide produces a codon that codes for the same amino acid

Question 14

What are missense mutations?

Answer 14

A mutation in the DNA sequence that results in a change in amino acid production.
This can have minimal or major effects depending on specific amino acid properties

Question 15

What mutation occurs when a stop codon is put into place prematurely?

Answer 15

A nonsense mutation.

Question 16

What mutation occurs when a stop mutation mutates and gets lost?

Answer 16

A sense mutation.

Question 17

What are agents that increase mutation rates?

Answer 17

Mutagens.

Question 18

When do deletion and insertion mutations have minimal impact?

Answer 18

When they occur in intron or non-coding nucleotide sequences.

Question 19

Why do deletion and insertion mutations often have a disastrous effect on encoded proteins?

Answer 19

The codon reading frame is altered if the deletion or insertion does not involve a multiple of 3 nucleotides.

Question 20

Do mutations occur spontaneously?

Answer 20

Yes.

Question 21

Do mutations occur spontaneously?

Answer 21

Yes.
However, there is a higher frequency of mutations when mutagens are present.

Question 22

Are most mutations harmful?

Answer 22

Yes.

Question 23

What is a potential benefit of mutations?

Answer 23

Genetic variation.

Question 24

What are the types of mutagens?

Answer 24

1. Physical agents. includes UV and ionising radiation
2. Chemical agents. includes chemicals that interact with DNA

Question 25

What types of mutations cause human genetic disorders?

Answer 25

Germline mutations.

Question 26

What are oncogenes?

Answer 26

Mutated genes involved in cell growth or cell division.
Normal cells are proto-oncogenes.

Question 27

What are tumour suppressor genes?

Answer 27

Protein products that inhibit cell division.

Question 28

What are the 3 stages of tumour growth?

Answer 28

1. Benign. Starts with single mutation and contained.
2. Malignant. Begining to penetrative surrounding tissue.
3. Metastatic. Spreading throughout the body.

Question 29

What is polymorphism?

Answer 29

A DNA variant that is acceptable.

Question 30

What are translocation mutations?

Answer 30

The changing of segments from one chromosome to a nonhomologous chromosome.
Can be reciprocal or non-reciprocal.

Question 31

What most commonly causes defects in genes that control cell growth or division?

Answer 31

Environmental factors.