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Genetics > Lecture--Chapter 13 > Flashcards

Lecture--Chapter 13 Flashcards

(85 cards)

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1
Q

DNA strands are _____ and _____.

A

complementary; antiparallel

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2
Q

template strand specifies its complement

A

Chargaff’s rule

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3
Q

DNA strands have a ____ phosphate end and ____ OH end, replication is _____.

A

5’; 3’; directional

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4
Q

The two DNA strands separate, with each strand used as a template for synthesis of _____.

A

daughter strands

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5
Q

Replication is _____.

A

semi-conservative

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6
Q

Steps of bacterial replication:

A
  1. initiation
  2. elongation
  3. termination
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7
Q

Initiation of DNA replication starts at the ______.

A

origin of replication (oriC)

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8
Q

site where parental DNA strands have separated and new daughter strands are being made

A

replication fork

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9
Q

Elongation and ___ of new DNA.

A

synthesis

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10
Q

Replication is _____.

A

bidirectional

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11
Q

replication forks meet on opposite side of the circle and chromosomes separate

A

termination

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12
Q

motifs that bind proteins

A

sequence “boxes”

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13
Q

controls timing of replication

A

GATC methylation

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14
Q

Initiation of DNA replication: _____ initiators, separation of ____ region.

A

dnaA protein; AT-rich

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15
Q

Initiation of DNA replication: Binding of _____, establishing the _____.

A

helicase; 2 replication forks

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16
Q

Initiation of DNA replication: ____ and other proteins bind and unwind DNA.

A

DNA helicase

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17
Q

Initiation of DNA replication: ____ generates positive supercoiling ahead of each replication fork.

A

DNA helicase

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18
Q

Initiation of DNA replication: _____ travels ahead of the helicase and relieves positive supercoils.

A

DNA gyrase (topoisomerase II)

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19
Q

Initiation of DNA replication: ______ bind to the separated strands to keep them apart.

A

single-strand DNA binding proteins

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20
Q

enzymes that copy DNA

A

DNA polymerases

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21
Q

the primary polymerase of replication

A

DNA polymerase III (DNA Pol III)

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22
Q

has a role in “lagging strand” replication

A

DNA polymerase I (DNA Pol I)

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23
Q

DNA polymerases are:

A
  1. primer dependent
  2. directional
  3. processive
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24
Q

DNA polymerases: only can add nucleotides to a primer

A

primer dependent

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25
DNA polymerases: can only synthesise 5' to 3'
directional
26
DNA polymerases: remain on the strand and catalyse consecutive reactions
processive
27
___ enters catalytic site
dNTP
28
Base pairing according to _____ rule.
AT/GC
29
A phosphodiester bond forms between:
5'-P of entering dNTP and 3'-OH of the sugar of the previous deoxynucleotide
30
Outer 2 phosphates of a phosphodiester bond are ____.
released
31
occurs at the replication fork
elongation
32
part of elongation: binds to ssDNA, synthesises short complementary RNA strands
primase
33
part of elongation: complex of helicase, primase, and Pol III.
replisome
34
part of elongation: short, newly synthesised DNA fragments that are formed on the lagging template strand
Okazaki fragments
35
Elongation: DNA Pol III: On leading strand, moves continuously towards the ____ and covalently bonds the next ____.
replication fork; nucleotide
36
Elongation: DNA Pol III: On lagging strand, periodically releases the strand, then reforms ____ at replication fork.
replisome
37
Elongation: DNA Pol III: adds ~___ nucleotides per second.
400
38
Elongation: DNA Pol I: Removes RNA primers by ____ activity.
5'--3' exonuclease
39
Elongation: DNA Pol I: fills in segment with ___
DNA
40
Elongation: DNA Pol I: ____ makes final seal.
DNA ligase
41
Termination: termination sequences on chromosome, opposite oriC.
Ter
42
Termination: proteins bind to ___.
Tus (termination utilisation substance)
43
Termination: Replication forks stop when they encounter ___.
Tus
44
Termination: ____ dissociates, ____ seals the new strands.
replisome; DNA ligase
45
2 intertwined DNA molecules
catenenes
46
DNA gyrase ___ the molecules.
decatenates
47
DNA synthesis has very high ____, 1 error per 108 bases.
fidelity
48
Mismatched ___ is unstable.
base pairing
49
DNA Pol III has 3' to 5' exonuclease activity
proofreading
50
General features of Eukaryotic DNA replication: more complex, though includes many of the same ____.
enzymes
51
General features of Eukaryotic DNA replication: Eukaryotic chromosomes are large, linear, and packed in ____.
nucleosomes
52
General features of Eukaryotic DNA replication: Multiple ____ per chromosome.
origins of replication
53
Numerous polymerases with specialised roles
eukaryotic DNA polymerases
54
catalyse by-pass segments around damaged DNA
lesion-replicating polymerases
55
Elongation: removes the RNA primers
flap endonuclease
56
Elongation: ___ fills in the gap.
DNA pol delta
57
repetitive tandem arrays of 12-16 at the ends of chromosomes
telomeres
58
Importance of telomeres: The ___ end cannot be otherwise replicated.
3'
59
Importance of telomeres: Protect the chromosome from ____, ____, or ____.
degradation; fusions; rearrangements
60
have a 3' overhang at the ends of chromosomes
telomeres
61
synthesises telomeres on one strand using its own RNA template
telomerase
62
gradually shorten, which limits cellular life-spans
telomeres
63
the exchange of DNA between similar or identical segments is found in all species
homologous recombination
64
Homologous recombination is best understood in ____.
E. coli
65
In eukaryotes, homologous recombination usually occurs in ____.
meiosis I
66
Exchange of DNA between non-sister ____ of homologous chromosomes.
chromatids
67
Proposed by Robin Holliday in 1964 based on studies of fungi
The Holliday Model
68
a mobile junction that forms between 4 strands of DNA
Holliday junction
69
The Holliday junction must be ___ to restore duplex DNA.
separated
70
The Holliday Model: homologous chromosomes align and are ____.
nicked
71
The Holliday Model: a single strand separates from its complementary strand, and basepairs with its complement in the sister chromatid
strand invasion
72
The Holliday Model: ______ formation between the 4 strands.
Holliday junction
73
The Holliday Model: ____ can continue for some distance along the chromatid and form a ____. This is known as ___.
strand swap; heteroduplex; branch migration
74
The Holliday Model: eventually another nick may stop the process and the strands are rejoined
resolution
75
The Holliday Model: both chromatids are nicked at _____ locations.
identical
76
The Holliday Model: The DNA strands to the ___ of the nicks invade the homologous chromosomes and attach to the strands to the ___ of the nicks.
left; right
77
The Holliday Model: The Holliday junction migrates from ___ to ____. This is called ____. It creates 2 ____ regions.
left; right; branch migration; heteroduplex
78
The Holliday Model: Two heteroduplex regions that have a few base _____.
mismatches (heteroduplex DNA)
79
Double-Strand Break Model: both backbones are broken in one ___, and some DNA is degraded.
chromatid
80
Double-Strand Break Model: ____ uses the other chromatid as a template for replacing lost DNA.
Gap repair function
81
Double-Strand Break Model: Gap repair function produces 2 _____.
Holliday junctions
82
one allele can replace the alternate allele
gene conversion
83
Gene conversion: DNA ___ repair or DNA ___ repair.
gap; mismatch
84
Gene conversion: DNA repair will _______.
correct the mismatches of heteroduplexes
85
chance of sequence of the invading strand being used as a template for correction:
50/50

Genetics (18 decks)

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