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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