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BIO 1200 > Chapter 11: DNA Replication And DNA Structure > Flashcards

Chapter 11: DNA Replication And DNA Structure Flashcards

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Biology 101 flashcards
1
Q

what are nucleotides made of?

A

nucleotides: 5 carbon sugar, phosphate, and nitrogenous base

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2
Q

what sugar is in RNA?

A

ribose in ribonucleotides

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3
Q

what sugar is in DNA?

A

deoxyribose in deoxyribosenucleotides

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4
Q

what are purines and examples?

A

bases with 2 rings
adenine and guanine

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5
Q

what are the nitrogenous bases?

A

purines and pyrimidines

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6
Q

what are pyrimidines and examples?

A

based with only 1 ring
cytosine, thymine, uracil

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7
Q

what are the bases in RNA and DNA?

A

rna: AGCU
dna: AGCT

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8
Q

what does the first and last nucleotides have?

A

1st: 5’ phosphate group
Last: 3’ OH

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9
Q

what are phosphodiester bonds?

A

connect nucleotides on the same strand

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10
Q

what do h bonds connect?

A

bases in opposite strands to make base pairs

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11
Q

In DNA, what are the complementary bases base pairs?

A

AT
GC

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12
Q

what is the purpose of DNA replication?

A

make a new dna molecule identical to original dna

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13
Q

what does 1 double stranded dna become during replication?

A

2

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14
Q

what does the old strand of dna act as in dna replication?

A

template for the new strand of dna

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15
Q

which process is semi conservative?

A

dna replication

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16
Q

why is dna replication bidirectional?

A

dna opens up at ORI and replication proceeds towards both ends the dna

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17
Q

how many ORI do eukaryotic dna have?

A

multiple dispersed the length of the chromosome

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18
Q

dna replication proceeds ___ from each ORI until the ____

A

outward
newly made pieces of dna meet and are connected together

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19
Q

what is helicase?

A

enzyme: unwinds dsDNA

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20
Q

what is topoisomerase?

A

enzyme: unwinds dsDNA, introduces temporary single stranded nicks in DNA to unlink it

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21
Q

what is single stranded DNA binding proteins?

A

bind to unwound ssDNA and prevent it from reforming a double helix

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22
Q

makes cuts in one strand of DNA
DNA rotates quickly to remove kinks then break in
DNA is repaired

A

topoisomerase

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23
Q

what wedges the double strand open?

A

helicase

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24
Q

what is primate?

A

synthesizes short RNA primers

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25
Q

what is a primer?

A

short piece of RNA to which dNTPs (deoxyribonucleotide triphosphates) are added

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26
Q

what are the steps for primase?

A

1) rna primer is made
2) dNTPs are added to end of primer to make new strand of DNA by new enzyme

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27
Q

how are primers and other RNAs synthesized by RNA polymerase from scratch?

A

by adding the first nucleotide complementary to the DNA template

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28
Q

what can primers and other RNAs be synthesized by?

A

RNA polymerase

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29
Q

the enzyme that makes DNA (___) can only add nucleotides to ____

A

DNA polymerase
the end of the primer or existing piece of DNA

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30
Q

where does RNA polymerase start from?

A

scratch

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31
Q

which directions is DNA synthesis?

A

5-3 direction in strand that is being made

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32
Q

what is DNA polymerase?

A

an enzyme that adds dNTPs to a piece of nucleic acid

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33
Q

what does 5-3 polymerase activity add?

A

nucleotides to end of RNA primer or piece of DNA to make new strand of DNA

34
Q

what is DNA polymerase III?

A

main enzyme involved in synthesizing DNA

35
Q

what type of activity is 3-5 and what is it?

A

exonuclease activity
removes mismatched bases- proofreading

36
Q

what is nuclease?

A

breakdown or digest nucleic acid

37
Q

what strands does DNA polymerase III make DNA on?

A

leading and lagging

38
Q

what is a leading strand?

A

makes a very long piece of DNA

39
Q

what is lagging strands?

A

is made in pieces (Okazaki fragments)

40
Q

what does polymerase I do?

A

removes RNA primer and fills in gap with DNA

41
Q

what adds nt to piece of newly made DNA on both leading and lagging strands of DNA?

A

5-3 polymerase activity

42
Q

how many primers do the leading and lagging strands have?

A

leading- 1
lagging- multiple

43
Q

what is DNA ligase?

A

connects pieces of DNA together by making the last phosphodiester bond

44
Q

what is step 1A in dna replication and which enzymes?

A

DNA is unwound at origins of replication

helicase and topoisomerase

45
Q

what is step 1B of DNA replication and enzyme?

A

proteins bind to DNA and keep it single stranded (unwound) until it can be replicated

single stranded DNA binding proteins

46
Q

what is step 2 in DNA replication and enzyme?

A

makes the RNA primer

primase

47
Q

what is a short piece of RNA that acts as a starter for DNA synthesis?

A

primer

48
Q

what enzymes unwind DNA?

A

helicase and topoisomerase

49
Q

what is step 3 in DNA replication and enzyme?

A

dna is synthesized in the 5-3 direction on the newly made strand

DNA polymerase III (adds dNTPs to the RNA primers)

50
Q

long continuous piece of DNA that dna is made on?

A

leading

51
Q

short pieces of DNA (Okazaki fragments) that DNA is made on?

A

lagging

52
Q

what direction is leading strand made in?

A

the direction the template is unwound

53
Q

what direction is lagging strands made in?

A

opposite direction

54
Q

what is step 3A in DNA synthesis?

A

DNA polymerase makes a long continuous piece of DNA on the leading strand

55
Q

what is step 3B in DNA synthesis?

A

DNA polymerase III makes short pieces of DNA on the lagging strand

56
Q

what is step 3C in DNA replication and enzyme?

A

mismatched bases are removed by proofreading

DNA polymerase III using the 3-5 exonuclease activity

57
Q

what is step 4 in DNA replication and enzyme?

A

primers are removed and the gap filled with DNA

DNA polymerase I

58
Q

what removes primers and fills in the gaps?

A

polymerase I

59
Q

in step 4, all nucleotides are present but the 2 fragments are not connected to each other until next step because it’s missing

A

the last phosphodiester bond

60
Q

what is step 5 in DNA replication and enzyme?

A

dna fragments are joined together by making the last phosphodiester bond

dna ligase

61
Q

does DNA ligase add any nts?

A

no, it only makes phosphodiester bond

62
Q

what is the result of DNA replication?

A

2 identical molecules of DNA
each molecule has one old and new strand

63
Q

what is chromatin?

A

complex of DNA and protein
DNA is in the less folded, uncondensed form (partially unwound)

64
Q

what are chromosomes?

A

complex of DNA and protein
DNA is in the most tightly packed, condensed form of

65
Q

during the cell cycle DNA alternates from ___ to ____

A

chromatin (less compactly folded, uncondensed) and chromosome (most tightly folded condensed)

66
Q

when are chromosomes visible?

A

During mitosis and meiosis

67
Q

most of the time dna is in what form? And why?

A

chromatin
to use dna for replication it needs to be accessible therefore in the less tightly packed chromatin form

68
Q

what does chromatin form?

A

the nucleosome structure, the 10 nm fiber - beads on a string

69
Q

what are nucleosomes?

A

dna and protein

70
Q

how are nucleosomes formed?

A

dna is wrapped around a core of proteins

71
Q

how many times is DNA wrapped around the nucleosome?

A

1.65 turns- roughly 1.5

72
Q

what is the core of histone protein?

A

nucleosomes

73
Q

how many histone proteins do nucleosomes consist of and the names of them?

A

2 of each
H2A, H2B, H3, H4

74
Q

what does histone H1 do?

A

binds to the linker region of DNA

75
Q

what are nucleosomes connected by?

A

linker regions of dna

76
Q

the nucleosome structure looks like

A

beads on a string

77
Q

what is level 3 of the chromosome structure?

A

the nucleosome structure is folded in a zigzag pattern to form the 30 nm fiber

78
Q

what is level 1 of chromatin structure?

A

dna double helix- 2 nm

79
Q

what is level 2 of chromatin structure?

A

nucleosomes, beads on a string - 10 nm

80
Q

what is level 4 of chromatin structure?

A

radial loop domains
the 30 nm is folded into radial loop domains, that are attached to proteins in the nuclear matrix

81
Q

what is the last level of chromatin structure?

A

chromosome
radial loops are folded up into chromosomes

82
Q

what do both polymerase do?

A

proofread- exonuclease activity

BIO 1200 (17 decks)

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