Biochemistry: Genetic material Flashcards Preview

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Flashcards in Biochemistry: Genetic material Deck (23)
1

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

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

2

Direction in which DNA is synthesized:

5' -> 3'

3

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

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

4

Two proteins make up the primeosome for DNA synthesis:

Primase
Helicase

5

There are four eukaryotic DNA polymerases:

a, d, b, g

6

How do thymine-thymine dimers happen?

Usually UV light damage.
Thymine - thymine is paired on the same DNA strand.

7

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

Nucleotide excision repair.
Xeroderma pigmentosum.

8

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

Base excision repair.

9

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

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

10

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

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

11

This DNA repair mechanism is defective in HNPCC:

Mismatch repair

12

What is the DNA repair defect associated with ataxia telangiectazia?

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

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?

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

14

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

Decreased numbers of T lymphocytes
Low IgA

15

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

Ataxia telangiectasia

16

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

dsDNA repair / non-homologous end joining

17

The strand of DNA nucleotides that opposes this DNA strand:
5' ATTGCGTA 3'

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

18

Main way in which UV light damages DNA:

Forms thymine-thymine dimers and the same strand of DNA

19

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

DNA polymerase alpha

20

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

DNA polymerase Delta
makes leaDing strand

21

The eukaryotic DNA polymerase responsible for replicating mitochondrial DNA:

DNA polymerase gamma

22

The eukaryotic DNA polymerase responsible for repairing DNA:

DNA polymerase beta

23

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