Chapter 8 CMB Genetic Mutation

Question 1

Name the 2 mutations named after cell types

Answer 1

1) Germ line mutations
2) Somatic mutations

Question 2

What is a germ line mutation?

Answer 2

Changes in gametes - pass on to offspring

Question 3

What is a somatic mutation?

Answer 3

Changes in body cells - very important in causing cancer

Question 4

*What can mutations result in? (4 examples) NMDD

Answer 4

1) Neutral condition (no effect)
2) Malfunction/Loss of function/Gain of function
3) Diseases/Disorders
4) Lethal/Death

Question 5

*What are the causes of mutations? (6 causes)

Answer 5

(Only 3 causes tested)
1. Errors in DNA replication
2. Errors in cell cycle check points
3. Error in DNA repair mechanisms
4. Exposure to radiation, heavy metals and chemicals.
5. Organisms – Bacteria, pathogens and others.
6. Non-living thing – Virus

Question 6

What does the linear array of the nucleotides in DNA/mRNA determine?

Answer 6

It determines the fate of the protein structure and function

Question 7

What are the 3 types of mutations?

Answer 7

1. Point mutation
2. Frameshift mutation
3. Exon skipping

Question 8

*What is point mutation and what are the 3 types?

Answer 8

Point mutation is the replacement of single nucleotide pair (base pair)
1. Silent
2. Missense
3. Nonsense

Question 9

*What is frameshift mutation and what are the 2 types?

Answer 9

Frameshift mutation is the insertion or deletion of one or more nucleotide pairs
1. Deletion
2. Insertion

Question 10

What is exon skipping?

Answer 10

Mutation in splicing acceptor site

Question 11

What is silent mutation?

Answer 11

No change in amino acid in the protein sequence
Eg. GCA become GCG but codon still codes for arganine

Question 12

What are the consequences of silent mutation?

Answer 12

No consequences

Question 13

What is denaturation of proteins?

Answer 13

loss of secondary, tertiary, quarternary structure or loss of shape

Question 14

*State an example of denaturation of proteins

Answer 14

Single amino acid change in hemoglobin (from glutamic acid to valine) can cause sickle cell anemia due to the distortion which affects its ability to carry oxygen

Question 15

What is missense mutation?

Answer 15

A base substitution which results in an amino acid change.
May have very serious consequences (depends)

Question 16

Give an example of missense mutation

Answer 16

Sickle-cell anemia is caused by the change in amino acid in the hemoglobin (Glutamic > Valine) which affects its ability to carry oxygen.

Question 17

What is nonsense mutation (premature termination)?

Answer 17

Nonsense mutation is the base substitution in a protein coding region which may mutate an amino acid codon to a stop codon or vice versa. This results in a prematurely shortened protein.

Question 18

*What is frameshift mutation?

Answer 18

Frameshift mutation is due to insertion or deletion of one or more nucleotides in the coding region of a gene

Question 19

*What does frameshift mutation cause? (3 steps)

Answer 19

1) It can cause an alteration of the reading frame, since codons are groups of three nucleotides.
2) Changes all the amino acids downstream and may create a non-functional protein, which may differ greatly from the normal protein
3) Reading frames containing stop codons will shorten the mutant protein prematurely

Question 20

*What are the 2 chemicals altering DNA structure?

Answer 20

1. Psoralens
2. Peroxides

Question 21

What are Psoralens?

Answer 21

Found in some vegetables and used in treatments of some skin conditions which causes intra- and inter-strand cross links

Question 22

What are Peroxides?

Answer 22

Chemicals causing DNA strand breaks

Question 23

*What are some types of radiation that causes mutations? (3 types)

Answer 23

1. X ray, gamma and cosmic rays
2. Radioactive elements
3. UV radiation

Question 24

What are X ray, gamma and cosmic rays? (radiation)

Answer 24

They are energetic enough that the produce reactive ions (charged atoms or molecules) that can break the DNA duplex

Question 25

What are radioactive elements? (radiation)

Answer 25

C14, Cesium 137, (Lead Tags)

Question 26

What is UV radiation?

Answer 26

It is not ionizing but can react with DNA and make thymine dimer (T-T)

Question 27

What is the relationship between X-ray dose and X-linked recessive disease due to mutation?

Answer 27

Linear relationship