Biochemistry: Genetic material

Question 1

Enzyme in DNA synthesis that allows uncoiling of supercoiled strand:
One drug that inhibits topoisomerase in prokaryotes? Eukaryotes?

Answer 1

Topoisomerase
Fluoroquinolones = prokaryotic inhibitor
Etoposide = eukaryotic inhibitor (anti-CA drug)

Question 2

Direction in which DNA is synthesized:

Answer 2

5’ -> 3’

Question 3

This Ab is made against topoisomerase. What is the disease it is associated with?

Answer 3

Anti-Scl-70 = Ab vs. topoisomerase
Diffuse scleroderma
NOT CREST

Question 4

Two proteins make up the primeosome for DNA synthesis:

Answer 4

Primase

Helicase

Question 5

There are four eukaryotic DNA polymerases:

Answer 5

a, d, b, g

Question 6

How do thymine-thymine dimers happen?

Answer 6

Usually UV light damage.

Thymine - thymine is paired on the same DNA strand.

Question 7

This DNA repair mechanism repairs bulky helix-distorting lesions:
Name one disease associated with a defect in this repair mechanism:

Answer 7

Nucleotide excision repair.

Xeroderma pigmentosum.

Question 8

This DNA repair mechanism is important in repair of spontaneous deamination:

Answer 8

Base excision repair.

Question 9

This disease results from a defect in DNA helicase specifically. Name three features:

Answer 9

Bloom syndrome.
Leukemias / lymphomas
Cancer by age 25 on average
Sensitivity to sunlight

Question 10

What is the DNA repair defect in xeroderma pigmentosum? Three features of the disease:

Answer 10

Defect in nucleotide excision repair
Dry skin
Absolutely no sunlight, ever
Melanomas and other cancers

Question 11

This DNA repair mechanism is defective in HNPCC:

Answer 11

Mismatch repair

Question 12

What is the DNA repair defect associated with ataxia telangiectazia?

Answer 12

Defect in ds break repair / non-homologous end joining.

Question 13

In ataxia telangiectasia, what is the first physical sign? Possible laboratory abnormality one might see after 8mos? At what age would you see telangiectasias?

Answer 13

Ataxia / difficulty with smooth visual pursuit, may fail to develop social smile
Elevated AFP possibly around 8 months
Telangiectasias not until age 5

Question 14

What is the immune deficiency associated with ataxia telangectasia (2 components)?

Answer 14

Decreased numbers of T lymphocytes

Low IgA

Question 15

Children with this disease are very sensitive to ionizing radiation in particular:

Answer 15

Ataxia telangiectasia

Question 16

What is the DNA repair defect associated with BRCA1 and BRCA2?

Answer 16

dsDNA repair / non-homologous end joining

Question 17

The strand of DNA nucleotides that opposes this DNA strand:

5’ ATTGCGTA 3’

Answer 17

Remember to write it 5’ to 3’
3’ to 5’ would be TAACGCAT, so the answer is
5’ TACGCAAT 3’

Question 18

Main way in which UV light damages DNA:

Answer 18

Forms thymine-thymine dimers and the same strand of DNA

Question 19

The eukaryotic DNA polymerase responsible for replicating the lagging strand of DNA:

Answer 19

DNA polymerase alpha

Question 20

The eukaryotic DNA polymerase responsible for replicating the leading strand of DNA:

Answer 20

DNA polymerase Delta

makes leaDing strand

Question 21

The eukaryotic DNA polymerase responsible for replicating mitochondrial DNA:

Answer 21

DNA polymerase gamma

Question 22

The eukaryotic DNA polymerase responsible for repairing DNA:

Answer 22

DNA polymerase beta

Question 23

Test

Answer 23

Test