DNA replication Flashcards

1
Q

Role of Magnesium ions (Mg 2+)

A

Required for DNA polymerase activity

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2
Q

Zidovudine can:

A

-Prolong life in HIV infected individuals
-Reduce mother to baby transmission by more than 20%

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3
Q

Initiator proteins (DNaA protein)

A

Binds to origin of replication and breaks hydrogen bonds between bases

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4
Q

DNA helicase (DNaB)

A

Opens helix and binds primase to form primosome

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5
Q

Helicase inhibitor (DNaC)

A

Delivers helicase to DNA template

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6
Q

DNA primase

A

An RNA polymerase that synthesizes a RNA primer on the lagging strand to enable DNA polymerase to synthesize DNA strand

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7
Q

DNA polymerase I

A

Remove RNA primer and replace with DNA

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8
Q

DNA polymerase III

A

Synthesis of leading and lagging strands

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9
Q

Single stranded binding protein (ssb)

A

Binds to single stranded DNA in the replication bubble and prevents it from reannealing or forming secondary structure

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10
Q

How are the Okazaki fragments joined together

A

DNA ligase

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11
Q

Lagging strand synthesis

A

Each Okazaki fragment requires a separate primer

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12
Q

How is DNA polymerase III loaded and maintained on the single stranded DNA template, and unloaded when it reaches double stranded DNA

A

Clamp protein

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13
Q

Clamp protein

A

Tightly holds the DNA polymerase onto the template for synthesis of long templates (increases expressivity), and releases DNA pol when it stalls at a region of double stranded DNA

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14
Q

For a bacterial replication fork moving at 500 bp per second, the parental DNA helix ahead of the fork must rotate at 50 revolutions per minute. This generates positive supercoils ahead of the replication fork.

A

Swivel the DNA using Topoisomerase enzymes

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15
Q

DNA gyrase (type II topoisomerase)

A

This enzyme introduces negative supercoils into the DNA. This reduces the positive supercoils introduced by the opening of the DNA. Also aids in the separation of the DNA during replication and transcription.

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16
Q

Ciprofloxacin

A

Is a quinolone drug that inhibits bacterial DNA gyrase. It is used in the treatment of respiratory and UTI and can be used to treat anthrax.

17
Q

Camptothecin

A

An anticancer drug, binds to and inhibits topoisomerase I activity. The result is DNA breakage

18
Q

Etoposide

A

Another anticancer drug, inhibits the activity of topoisomerase II

19
Q

SNP

A

Single Nucleotide Polymorphism: Formally defined as a variant that is found at least in 1% of the population. Single base pair change between individuals.

20
Q

SSR (Simple Sequence Repeat)

A

These are the most simple type of repetitive sequence; and most polymorphic

21
Q

VNTR

A

Short tandem repeats. A bit longer than the SSR.

22
Q

LCR

A

Low copy repeat

23
Q

Pleiotropy

A

Many different features (phenotypic manifestations, all ascribed to a single genetic cause)

24
Q

Myotonia

A

Reduced ability to relax after a muscle contraction

25
Q

Myoclonus

A

Quick, involuntary muscle jerk

26
Q

Haplo-insufficiency

A

Loss-of-function mutations in which half normal levels (50%) of the gene product result in phenotypic effects. Reduced protein levels (50%) are not sufficient to carry out the normal functions of that protein.

27
Q

Dominant-Negative mutations

A

A mutant gene product interferes with function of the normal gene product. In some cases, assembly of the multimeric protein is affected (hindered) by the presence of the mutant protein.
-Produce a more severe phenotype than autosomal dominant by haploinsufficiency