DNA Replication II

Question 1

What are some mitochondrial DNA depletion syndromes, and what are some characteristics of them?

Answer 1

• progressive disease affecting: children, those treated for HIV-1 or HepB virus infections, young adults
• multi-organ disturbance
• considered rare, but difficult to diagnose and considered under represented
• Alpers syndrome, progressive external opthalmoplegia, ataxia-neuropathy syndrome

Question 2

What are the eukaryotic DNA polymerases?

Answer 2

Alpha- contains primase, initiates DNA synthesis, no proof reading
Beta- repair, no proof reading
Gamma- replicated mitochondrial DNA, proof reading
Delta- thought to elongate Okazaki fragments of lagging strand, proof reading
Epsilon- elongates leading strand, proof reading

-proofreading denotes 3’ to 5’ exonuclease activity

Question 3

In what part of the cell cycle does DNA replication occur?

Answer 3

S (DNA synthesis)

-Cancercanresultwhenchecks inthecellcycledonotproperlyoccurthatensurefidelityof thegenome.

Question 4

What are the differences in eukaryotic replication compared to prokaryotic?

Answer 4

Eukaryotic very similar in process but more complex. Proceeds at 50 bp/s compared to 1,000 bp/s, thought this is due to unpacking. Multiple origins of replication about every 30-300 kbp, with non-specific sequences that are AT rich (only 2 H bonds). Telomere replication differs. Polymerase nomenclature differs.

Question 5

Describe telomere structure?

Answer 5

Telomerestructurecontainsabufferregionof100‐300kbtelomereassociatedrepeats,
followedbya3-20kbregionoftandemTTAGGGrepeats,thenasinglestrandedregionofseveralhundredbasepairs(notshown)foldeduponitselfandboundbyproteins

• 2 types of repeated sequences that are lost with division, not important stuff
• protect the chromosome

Question 6

Describe Telomerase mechanism?

Answer 6

????? NC

Question 7

What’s important for mitochondrial DNA reading?

Answer 7

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