Mod 9- Effects Of DNA Mutations

Question 1

What are the effects of mutations on the information content of a gene?

Answer 1

Mutations can alter the information content by changing the sequence of nucleotides, potentially affecting gene expression and function.

This includes point mutations, insertions, deletions, and other types of mutations.

Question 2

Define point mutation.

Answer 2

One base pair is replaced with another (one base pair changes)

This can be classified into transitions and transversions.

Question 3

What is a transition mutation?

Answer 3

A mutation where a purine is replaced by another purine (A ↔ G) or a pyrimidine is replaced by another pyrimidine (T ↔ C).

Question 4

What is a transversion mutation?

Answer 4

A mutation where a purine is replaced by a pyrimidine or vice versa (A or G ↔ T or C).

Question 5

What occurs during an insertion mutation?

Answer 5

One or more base pairs are inserted into the DNA sequence.

Question 6

What occurs during a deletion mutation?

Answer 6

One or more base pairs are deleted from the DNA sequence.

Question 7

Define inversion mutation.

Answer 7

Two or more base pairs are excised and reinserted in the opposite orientation.

Question 8

What is a synonymous mutation?

Answer 8

A mutation that has no effect on the amino acid sequence, also called a silent mutation.

Question 9

What is a non-synonymous mutation?

Answer 9

A mutation that changes the amino acid sequence, also known as a missense mutation.

Question 10

What is a nonsense mutation?

Answer 10

A mutation that changes a codon for an amino acid into a stop codon.

this is detrimental

Question 11

What is a readthrough mutation?

Answer 11

A mutation that changes a stop codon to a codon for an amino acid.

This could change its function

Question 12

What is a frameshift mutation?

Answer 12

A mutation that changes the reading frame, altering all downstream codons.

Question 13

What are suppressive mutations?

Answer 13

Mutations that can reverse the effects of an earlier mutation, such as second site reversion.

Question 14

What are monogenic disorders?

Answer 14

Inherited diseases caused by defects in individual genes.

Question 15

What is one of the most common monogenic disorders in the UK?

Answer 15

Cystic Fibrosis.

Question 16

What does the cystic fibrosis transmembrane regulator (CFTR) gene do?

Answer 16

It directs the synthesis of the CFTR protein, which is a chloride channel responsible for the proper balance of salt and water within a cell.

Question 17

What is the most common mutation in CFTR among UK patients?

Answer 17

ΔF508 or F508del (68% of cases), which is a deletion of three nucleotides.

Question 18

What does the ΔF508 mutation remove?

Answer 18

A codon for phenylalanine (F), which is the 508th amino acid in the polypeptide.

Question 19

What is the second commonest CFTR mutation?

Answer 19

G542X (2.5% of cases), which is a nonsense mutation that changes glycine (G) at position 542 to a stop codon (X).

Question 20

What is the third commonest CFTR mutation?

Answer 20

G551D (1.5% of cases), a non-synonymous point mutation that changes glycine (G) at position 551 to aspartic acid (D).

Question 21

What is the treatment for Cystic Fibrosis that includes Ivacaftor and Lumacaftor?

Answer 21

Orkambi.

Question 22

What are mutations important for in organisms?

Answer 22

Evolution and diversity of organisms

Some mutations may also cause disease.

Question 23

What are monogenic disorders?

Answer 23

Inherited diseases caused by defects in individual genes.

Question 24

What does phenotype refer to?

Answer 24

Biological characteristics.

Question 25

What does it mean that most organisms are diploid?

Answer 25

They have two copies of each chromosome and gene.

Question 26

What are alleles?

Answer 26

Alternate forms of a gene.

Question 27

What is haploinsufficiency?

Answer 27

A condition where a mutation in just one gene causes disease.

Question 28

What is an example of a disorder caused by haploinsufficiency?

Answer 28

Mandibulofacial Dysostosis Guion Almeida type (MFDGA).

Question 29

What is a common result of large deletion mutations?

Answer 29

Diseases such as deletion of about 500 kb from the X chromosome.

Question 30

What is trisomy?

Answer 30

Three copies of a chromosome.

Question 31

What condition is caused by trisomy of chromosome 21?

Answer 31

Down syndrome.

Question 32

What is monosomy?

Answer 32

Where one chromosome is missing.

Question 33

What does a chromosome translocation involve?

Answer 33

Part of one chromosome becomes attached to another chromosome.

Question 34

What is the Philadelphia chromosome?

Answer 34

A common cause of leukemia associated with the bcr-abl gene.

Question 35

What happens when the bcr-abl gene is switched on all the time?

Answer 35

Cell division becomes uncontrolled.

Question 36

True or False: Not all human mutations are harmful.

Answer 36

True.

Question 37

What is the Apolipoprotein A-I ‘Milano’ variant associated with?

Answer 37

Low prevalence of cardiovascular disease in carriers.

Question 38

What mutation is associated with high bone density?

Answer 38

G171V missense mutation in LDL-Receptor–Related Protein 5 (LRP5).

Question 39

What is the relationship between red hair and pain sensitivity?

Answer 39

Individuals with red hair often require more anaesthesia due to a loss of MC1R function.

Question 40

What is a characteristic of natural short sleepers?

Answer 40

Lifelong short sleep with no obvious adverse outcomes.

Question 41

What mutation is associated with natural short sleep?

Answer 41

Missense mutation in DEC2 (DEC2-P384R).