Lippincott - DNA Structure, Replication, Repair Flashcards Preview

[OS 201] 3rd Exam > Lippincott - DNA Structure, Replication, Repair > Flashcards

Flashcards in Lippincott - DNA Structure, Replication, Repair Deck (85)
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1

DNA

polymer of deoxyribonucleoside monophosphates covalently linked by 3'-->5' phosphodiester bonds

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main bond in DNA

phosphodiester bond

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phosphodiester bond connects:

3'-hydroxyl group of one nucleotide to 5' hydroxyl group of adjacent nucleotide

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3' end

end with the free hydroxyl

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5' end

end with the free phosphate

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what enzyme family cleaves DNA

deoxyribonucleases

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what enzyme family cleaves RNA

ribonucleases

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orientation of single stranded DNA in double helix

antiparallel

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type of bond that mediates base pairing

hydrogen bond

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DNA - adenine pairs with:

thymine

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DNA - guanine pairs with:

cytosine

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DNA - thymine pairs with:

adenine

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DNA - cytosine pairs with:

guanine

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methods of DNA denaturation

altering pH (ionization), melting DNA

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number of H bonds between guanine and cytosine

3

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number of H bonds between adenine and thymine

2

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which bases are purines

adenine, guanine

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which bases are pyrimidines

thymine, cytosine

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number of rings in purines

2

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number of rings in pyrimidines

1

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what base pairing denatures at higher temperatures? why?

GC, because of greater number of H bonds

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process of reforming the double helix from single strands of DNA

renaturation or reannealing

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process of separating the double helix of DNA

denaturation

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major stuctural forms of the double helix

B form, A form, Z form

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B form

right handed helix with 10 residues per turn, main form of chromosomal DNA

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A form

right handed helix with 11 residues per turn, produced by dehydrating the B form

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Z form

left handed helix with 12 residues per turn, occur naturally in regions with alternating purines and pyrimidines (ex. poly GC)

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region where active DNA synthesis occurs

replication fork

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DnaA protein

binds to specific nucleotide sequences at origin, causing AT rich regions in the origin to melt

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DNA helicase

actively unwinds the double helix