Replication and Transcription Flashcards

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1
Q

what problem of DNA replication does helicase fix?

A

exposing the template strand

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2
Q

helicase

A

moves down the DNA and separates strands using energy from ATP, uses single stranded binding proteins

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3
Q

single stranded binding proteins

A

prevent bases from rebinding to each other which creates the replication fork

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4
Q

how does helicase move?

A

helicase moves in both directions which makes a replication bubble and 2 replication forks

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5
Q

origin of replication

A

specific DNA sequence where helicases and polymerases start replication

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6
Q

how many origins of replication does a prokaryote have?

A

one

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7
Q

what problem does topoisomerase fix?

A

supercoiling

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8
Q

supercoiling

A

unwinding of helix shape creates overwinding which hinders transcription and replication

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9
Q

topoisomerase

A

cuts strands, allows them to unwind, and then rejoins the 2 sides

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10
Q

what problem does RNA polymerase fix?

A

DNA polymerase does not know where to start

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11
Q

RNA polymerase/primase

A

builds a short RNA primer so DNA polymerase can add DNA to the primer; DNA polymerase comes from other side and replaces primer

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12
Q

what direction is DNA replicated (built) in?

A

5’ to 3’ (starts at 3’ end of parent strand)

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13
Q

DNA ligase

A

joins together 2 replicated DNA fragments

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14
Q

why do leading and lagging strands occur?

A

helicase unwinds both strands 3’ to 5’ and 5’ to 3’ but DNA polymerase only elongates new strands 5’ to 3’

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15
Q

leading strands

A

leading strands are already going in the 5’ to 3’ direction of the new strand; replication chases helicase

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16
Q

lagging strands

A

lagging strands are 3’ to 5’ so replication must keep restarting generating Okazaki fragments

17
Q

Okazaki fragments

A

the fragments created by the replication of lagging strands

18
Q

telomere

A

the ends of chromosomes/DNA strands, get shorter with age

19
Q

telomerase

A

adds nucleotides to template strand which makes an extension RNA primer can bind to, and no DNA will be lost (not all cells have it)

20
Q

which tells have telomerase?

A

germline cells, stem cells, cancer cells