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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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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
what is a primer?
short piece of RNA to which dNTPs (deoxyribonucleotide triphosphates) are added
26
what are the steps for primase?
1) rna primer is made 2) dNTPs are added to end of primer to make new strand of DNA by new enzyme
27
how are primers and other RNAs synthesized by RNA polymerase from scratch?
by adding the first nucleotide complementary to the DNA template
28
what can primers and other RNAs be synthesized by?
RNA polymerase
29
the enzyme that makes DNA (___) can only add nucleotides to ____
DNA polymerase the end of the primer or existing piece of DNA
30
where does RNA polymerase start from?
scratch
31
which directions is DNA synthesis?
5-3 direction in strand that is being made
32
what is DNA polymerase?
an enzyme that adds dNTPs to a piece of nucleic acid
33
what does 5-3 polymerase activity add?
nucleotides to end of RNA primer or piece of DNA to make new strand of DNA
34
what is DNA polymerase III?
main enzyme involved in synthesizing DNA
35
what type of activity is 3-5 and what is it?
exonuclease activity removes mismatched bases- proofreading
36
what is nuclease?
breakdown or digest nucleic acid
37
what strands does DNA polymerase III make DNA on?
leading and lagging
38
what is a leading strand?
makes a very long piece of DNA
39
what is lagging strands?
is made in pieces (Okazaki fragments)
40
what does polymerase I do?
removes RNA primer and fills in gap with DNA
41
what adds nt to piece of newly made DNA on both leading and lagging strands of DNA?
5-3 polymerase activity
42
how many primers do the leading and lagging strands have?
leading- 1 lagging- multiple
43
what is DNA ligase?
connects pieces of DNA together by making the last phosphodiester bond
44
what is step 1A in dna replication and which enzymes?
DNA is unwound at origins of replication helicase and topoisomerase
45
what is step 1B of DNA replication and enzyme?
proteins bind to DNA and keep it single stranded (unwound) until it can be replicated single stranded DNA binding proteins
46
what is step 2 in DNA replication and enzyme?
makes the RNA primer primase
47
what is a short piece of RNA that acts as a starter for DNA synthesis?
primer
48
what enzymes unwind DNA?
helicase and topoisomerase
49
what is step 3 in DNA replication and enzyme?
dna is synthesized in the 5-3 direction on the newly made strand DNA polymerase III (adds dNTPs to the RNA primers)
50
long continuous piece of DNA that dna is made on?
leading
51
short pieces of DNA (Okazaki fragments) that DNA is made on?
lagging
52
what direction is leading strand made in?
the direction the template is unwound
53
what direction is lagging strands made in?
opposite direction
54
what is step 3A in DNA synthesis?
DNA polymerase makes a long continuous piece of DNA on the leading strand
55
what is step 3B in DNA synthesis?
DNA polymerase III makes short pieces of DNA on the lagging strand
56
what is step 3C in DNA replication and enzyme?
mismatched bases are removed by proofreading DNA polymerase III using the 3-5 exonuclease activity
57
what is step 4 in DNA replication and enzyme?
primers are removed and the gap filled with DNA DNA polymerase I
58
what removes primers and fills in the gaps?
polymerase I
59
in step 4, all nucleotides are present but the 2 fragments are not connected to each other until next step because it’s missing
the last phosphodiester bond
60
what is step 5 in DNA replication and enzyme?
dna fragments are joined together by making the last phosphodiester bond dna ligase
61
does DNA ligase add any nts?
no, it only makes phosphodiester bond
62
what is the result of DNA replication?
2 identical molecules of DNA each molecule has one old and new strand
63
what is chromatin?
complex of DNA and protein DNA is in the less folded, uncondensed form (partially unwound)
64
what are chromosomes?
complex of DNA and protein DNA is in the most tightly packed, condensed form of
65
during the cell cycle DNA alternates from ___ to ____
chromatin (less compactly folded, uncondensed) and chromosome (most tightly folded condensed)
66
when are chromosomes visible?
During mitosis and meiosis
67
most of the time dna is in what form? And why?
chromatin to use dna for replication it needs to be accessible therefore in the less tightly packed chromatin form
68
what does chromatin form?
the nucleosome structure, the 10 nm fiber - beads on a string
69
what are nucleosomes?
dna and protein
70
how are nucleosomes formed?
dna is wrapped around a core of proteins
71
how many times is DNA wrapped around the nucleosome?
1.65 turns- roughly 1.5
72
what is the core of histone protein?
nucleosomes
73
how many histone proteins do nucleosomes consist of and the names of them?
2 of each H2A, H2B, H3, H4
74
what does histone H1 do?
binds to the linker region of DNA
75
what are nucleosomes connected by?
linker regions of dna
76
the nucleosome structure looks like
beads on a string
77
what is level 3 of the chromosome structure?
the nucleosome structure is folded in a zigzag pattern to form the 30 nm fiber
78
what is level 1 of chromatin structure?
dna double helix- 2 nm
79
what is level 2 of chromatin structure?
nucleosomes, beads on a string - 10 nm
80
what is level 4 of chromatin structure?
radial loop domains the 30 nm is folded into radial loop domains, that are attached to proteins in the nuclear matrix
81
what is the last level of chromatin structure?
chromosome radial loops are folded up into chromosomes
82
what do both polymerase do?
proofread- exonuclease activity

BIO 1200 (17 decks)

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