Week 2-DNA REPLICATION AND REPAIR

Question 1

What is the central dogma of molecular biology?

Answer 1

DNA - RNA - Protein

Question 2

What are the three types of stop codons?

Answer 2

• UAA
• UAG
• UGA

Question 3

How many codons are there in the genetic code?

Answer 3

64 codons

Question 4

How many amino acids are encoded by the genetic code?

Answer 4

20 amino acids

Question 5

What does the ‘wobble hypothesis’ refer to?

Answer 5

1 tRNA may bind with +1 codons

Question 6

What is a mutation?

Answer 6

A permanent alteration in genetic structure

Question 7

What are the two types of mutations?

Answer 7

• Gross change involving several/many nucleotides
• Change involving a single nucleotide

Question 8

What is a point mutation?

Answer 8

Change involving a single nucleotide

Question 9

What are the three types of base substitutions?

Answer 9

• Silent mutation
• Nonsense mutation
• Missense mutation

Question 10

What is a silent mutation?

Answer 10

No change in amino acid translated

Question 11

What is a nonsense mutation?

Answer 11

‘Stop’ codon formed

Question 12

What is a missense mutation?

Answer 12

Change in amino acid translated

Question 13

What is a frameshift mutation?

Answer 13

Extensive codon changes downstream from insertion or deletion

Question 14

What is cystic fibrosis inherited in?

Answer 14

Autosomal recessive manner

Question 15

What is the cytogenetic location of the CFTR gene for cystic fibrosis?

Answer 15

7q31.2 base pairs 117,120,016 to 117,308,718

Question 16

What does mutagenesis refer to?

Answer 16

The process by which mutations arise

Question 17

What are the two types of mutation origins?

Answer 17

• Spontaneous
• Induced

Question 18

What is a tautomeric shift?

Answer 18

Transient change in base structures

Question 19

What is the role of DNA polymerase during replication?

Answer 19

Synthesizes DNA 5’ to 3’ and has 3’ to 5’ exonuclease activity

Question 20

What happens if a spontaneous mutation is not corrected?

Answer 20

May undergo mismatch repair following replication

Question 21

What is xeroderma pigmentosum?

Answer 21

Rare autosomal recessive disorder with elevated risk of developing sunlight-induced cancers

Question 22

What is the primary defect in xeroderma pigmentosum?

Answer 22

Deficiency in nucleotide excision repair complex

Question 23

What is the first step toward gene therapy for xeroderma pigmentosum?

Answer 23

Correction of 2 base pair deletion in XPC gene

Question 24

What is the genetic disorder caused by a defect in the CFTR protein?

Answer 24

Cystic fibrosis

Question 25

Fill in the blank: The genetic code is _______.

Answer 25

[degenerate]

Question 26

True or False: All mutations lead to genetic disorders.

Answer 26

False