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Genetics > Chapter Thirteen: The Eukaryotic Chromosome > Flashcards

Chapter Thirteen: The Eukaryotic Chromosome Flashcards

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1
Q

all cells have ___ nuclear DNA, but cells are ___ from one another

A

identical
different

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2
Q

chromosomes support the ___, ___, ___, and ___ of genetic information

A

packaging, replication, segregation, and expression

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3
Q

generic term for any complex of DNA and protein found in the nucleus of a cell

A

chromatin

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4
Q

chromosomes are separate pieces of ___ that behave as a unit during ___

A

chromatin
cell division

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5
Q

chromatin is made up of roughly ___, ___, ___, and ___

A

1/3 DNA, 1/3 histones, 1/3 nonhistone proteins, and significant amounts of RNA

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6
Q

DNA interaction with histones and nonhistone proteins produces a significant level of ___ to fit into a cell nucleus

A

compaction

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7
Q

histones are ___ proteins that are ___ charged and highly ___

A

small
positively
conserved

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8
Q

what does it mean for something to be conserved

A

the same throughout all life, serve the same purpose

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9
Q

histones function to ___ and ___ DNA

A

bind to and neutralize

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10
Q

five types of histones

A

H1, H2A, H2B, H3, and H4

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11
Q

H1-H4, make up the nucleosome, most rudimentary packaging unit

A

core histones

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12
Q

thousands of proteins that make up chromatin and are not histones

A

nonhistone proteins

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13
Q

are there more histone or nonhistone proteins

A

nonhistone

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14
Q

four functions of nonhistone proteins

A
  1. structural role
  2. chromosome replication
  3. chromosome segregation
  4. active in transport
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15
Q

when chromosomes are treated with ___, you can see the scaffolding of nonhistone proteins

A

detergent

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16
Q

help move chromosomes along the spindle apparatus, a nonhistone protein

A

kinetochore proteins

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17
Q

blue stain used in the nucleus

A

DAPI

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18
Q

when stretched out, the DNA in a single cell would be about ___

A

6 feet long

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19
Q

___ allows DNA to fit into a cell nucleus

A

compaction

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20
Q

structures formed by winding of DNA around histones, resemble beads on a string

A

nucleosome

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21
Q

nucleosome are the fundamental unit of ___

A

chromosomal packaging

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22
Q

___ and ___ of nucleosomes affect genetic function

A

spacing and structure

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23
Q

nucleosome ___ is highly defined and varies in different cell types and under different conditions

A

arrangement along chromatin

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24
Q

nucleosome core is an octamer of ___, contains histones ___

A

two
H2A, H2B, H3, H4

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25
Q

about ___ of DNA wrap twice around core of eight histones

A

160 bp

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26
Q

histone ___ is associated with linker DNA as it enters and leaves the nucleosome core

A

H1

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27
Q

DNA ___ as it wraps around the core histone octamer

A

bends sharply

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28
Q

___ dictates preferred nucleosome positions along the DNA

A

base sequence

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29
Q

chromosomal DNA appears as ____ of chromosome in electron micrographs

A

long loops anchored to scaffold backbone

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30
Q

protein complexes that form loops of DNA

A

condensins

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31
Q

___ protein subunits constitute condensins

A

five

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32
Q

condensins exist as ___ that form around the ___

A

rings
nucleosome

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33
Q

a model of higher-order chromosome packaging

A

nucleosome supercoiling

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34
Q

banding patterns in a karyotype reflect how ___ the DNA is

A

condensed

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35
Q

banding patterns on each chromosome are highly ___

A

reproduceable

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36
Q

diagrams of G-banding patterns

A

idiograms

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37
Q

short arm of a chromosome

A

P arm

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38
Q

long arm of a chromosome

A

Q arm

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39
Q

within each arm, light and dark bands are ___

A

numbered consecutively

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40
Q

a physical mapping approach where fluorescent tags are used to detect hybridization of nuclei acid probes with chromosomes

A

fluorescent in situ hybridization (FISH)

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41
Q

FISH allows the locating of ___ within a chromosome

A

specific DNA sequences

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42
Q

three general steps of FISH

A
  1. chromosomes are spread on a glass slide and denatured to make them single stranded
  2. a DNA sequence is labeled with a fluorescent tag to make a probe
  3. the probe hybridizes to chromosomes at complementary regions
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43
Q

how would you find the sequence ATCCGATC within a chromosome

A

fluorescent tag of complementary base sequences (TAGGCTAG)

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44
Q

a variation of FISH that has chromosome-specific probes each labeled with a different fluorescent dye

A

special karyotyping (SKY)

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45
Q

highly condensed form of chromatin, usually transcriptionally inactive

A

heterochromatin

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46
Q

heterochromatin is the ___ stained regions of the chromosome

A

darkly

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47
Q

heterochromatin that is condensed in all cells

A

constitutive

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48
Q

example of constitutive heterochromatin

A

most of the Y chromosome

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49
Q

heterochromatin that is condensed only in some cells and relaxed in other cells

A

facultative heterochromatin

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50
Q

example of relaxed heterochromatin

A

X chromosome in female mammals

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51
Q

chromatin that is relaxed, usually transcriptionally active

A

euchromatin

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52
Q

euchromatin is the ___ stained regions of chromosomes

A

lightly

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53
Q

transcription requires changes in chromatin ___

A

structure

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54
Q

promoters of inactive genes are hidden in ___

A

nucleosomes

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55
Q

to activate a gene, ___ bind to enhancers and recruit ___ proteins

A

transcription factors
chromatin remodeling

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56
Q

promoters are exposed by ___ or ___ nucleosomes

A

removing or repositioning

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57
Q

variable expression of a gene in a population of cells, caused by the gene’s location near highly compacted heterochromatin

A

position effect variegation (PEV)

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58
Q

the gene for white+ eyes in drosophila is normally located in ___

A

euchromatin

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59
Q

chromosomal inversion can result in the w+ gene being located adjacent to ___

A

heterochromatin

60
Q

heterochromatin can ___ adjacent genes

A

turn off

61
Q

___ can be caused by spreading of heterochromatin into nearby genes

A

spreading

62
Q

spreading of heterochromatin can occur over ___ of chromatin

A

> 1000kb

63
Q

in drosophila the w+ gene expresses a ___ phenotype; if the w+ gene is silenced, a ___ phenotype is expressed

A

red
white

64
Q

mutations in drosophila that enhanced heterochromatin formation made eyes ___

A

more white

65
Q

mutations in drosophila that suppressed heterochromatin formation made eyes ___

A

less white

66
Q

DNA segments that block the spread of heterochromatin

A

barrier elements

67
Q

extend out from the nucleosome and are platforms for modifications

A

histone tails

68
Q

the four core histone tails can be modified with ___

A

chemical groups

69
Q

extend out from the nucleosome and are platforms for modifications

A

histone tails

70
Q

___ can add chemical groups to histone tails

A

enzymes

71
Q

the modification of histone tails is a method of ___

A

differentiation between organisms with identical DNA

72
Q

modified histone tails can alter ___ and bind ___

A

nucleosomes
chromatin modifier proteins

73
Q

histone tail modification alter ___ structure

A

chromatin

74
Q

adds acetyl groups to histone tails

A

histone acetyltransferase

75
Q

acetylation prevents ___ of nucleosomes

A

close packaging

76
Q

acetylation favors ___ of genes in ___

A

expression
euchromatin

77
Q

removes acetyl groups from histone tails

A

histone deacetylase

78
Q

adds methyl groups to histone tails

A

histone methyltransferase

79
Q

the effect of histone tail methylation depends on which ___ is modified

A

amino acid

80
Q

methylation of H3 lysine 9 favors ___ formation

A

heterochromatin

81
Q

removes methyl groups from histone tails

A

histone demethylase

82
Q

X chromosome inactivation in female mammals occurs through ___

A

heterochromatin formation

83
Q

Barr bodies are an example of ___

A

facultative heterochromatin

84
Q

random X inactivation occurs about ___ after fertilization

A

2 weeks

85
Q

some cells have ___ X inactivated, some have ___ X inactivated; all cells descendants will have ___ X inactivated

A

maternal
paternal
the same

86
Q

X-inactivation is initiation by the expression of the ___

A

Xist gene

87
Q

Xist stands for ___

A

X inactivation specific transcript

88
Q

the xist gene is expressed in the ___ X chromosome but not on the ___ X chromosome

A

inactive
active

89
Q

Xist RNA is a ___, ___, ___-acting, ___ RNA

A

large, noncoding, cis-acting, regulatory

90
Q

Xist RNA binds to the X chromosome that it was ___, then initiates ___ that result in ___

A

expressed from
histone modifications
heterochromatin formation

91
Q

rate of DNA synthesis in human cells is about ___

A

50nt/sec

92
Q

accessible regions of DNA that are devoid of nucleosomes

A

origin of replication

93
Q

it would take ___ to replicate the human genome If there was only one origin of replication

A

800 hours

94
Q

s phase lasts about ___

A

8 hours

95
Q

most mammalian cells have about ___ origins of replication

A

10,000

96
Q

many origins are ___

A

active at the same time

97
Q

accessible regions of DNA that are devoid of nucleosomes

A

origin of replication

98
Q

DNA being replicated in both directions from one origin

A

replication unit / replicon

99
Q

nucleosomes are ___ and ___ during DNA replication

A

disassembled and reformed

100
Q

DNA is packaged in nucleosomes within ___ of synthesis

A

minutes

101
Q

new nucleosomes are composed of ___ and ___

A

recycled histones and new histones

102
Q

chromatin is open to ___ just after replication

A

histone modification

103
Q

“caps” that protect the ends of eukaryotic chromosomes

A

telomeres

104
Q

telomeres consist of ___, do not contain ___

A

specific repetitive sequences
genes

105
Q

telomere sequence in humans is ___; telomere sequence in tetrahymena

A

TTAGGG
TTGGGG

106
Q

telomeres prevent ___ and maintain ___

A

chromosome fusion
integrity of chromosomal ends

107
Q

for replication at the end of chromosomes, RNA primers are ___, which leaves a length of DNA ___ at the 5’ ends

A

removed
missing

108
Q

without a special mechanism, DNA would be ___ from every new DNA strand every cell cycle

A

lost

109
Q

a ribonucleoprotein that extends telomeres

A

telomerase

110
Q

___ is complementary to telomere repeated sequences and serves as a template for addition of new DNA to telomeres

A

telomerase RNA

111
Q

additional rounds of telomere elongation occur after telomerase ___

A

translocates to newly-synthesized end

112
Q

in humans, the levels of telomerase and cellular life span ___ between different types of cells

A

varies

113
Q

most somatic cells have ___ expression of telomerase

A

low

114
Q

somatic telomeres ___ at each cell division, senescence after ___ generations in culture

A

shorten
<50

115
Q

germ cells, stem cells, and tumor cells have ___ expression of telomerase; telomeres ___ at each cell division

A

high
maintain length

116
Q

proteins that bind to telomeres and fold the DNA

A

shelterin

117
Q

shelterins function to protect against ___ and ___

A

degradation by nucleases and non-homologous end joining (NHEJ)

118
Q

segregation of condensed chromosome depends on ___

A

centromeres

119
Q

during anaphase of mitosis and meiosis II, ___ must segregate to different daughter cells

A

sister chromatids

120
Q

during anaphase of meiosis I, ___ do not separate but ___ segregate to different cells

A

sister chromatids
homologous chromosomes

121
Q

two functions of centromeres

A

hold sister chromatids together
attachment sites for chromosome segregation machinery

122
Q

protein that holds sister chromatids together

A

cohesin

123
Q

specialized structure of DNA and protein at the centromere where chromosomes attach to spindle fibers

A

kinetochore

124
Q

yeast centromeres are two conserved ___ DNA sequences separated by ___

A

10-15bp
90bp

125
Q

proteins bind to DNA in a ___ fashion

A

sequence-dependent

126
Q

centromeres of higher eukaryotes are ___ and ___

A

larger and more complex

127
Q

centromeres of higher eukaryotes consist of ___ of ___

A

tandem repeats of noncoding satellite DNA

128
Q

kinetochores assemble at ___ and are the site of attachment for ___

A

centromeres
spindle fibers

129
Q

chromatin is ___ at the centromere

A

packaged differently

130
Q

at the centromere, H3 is replaced by the histone variant ___

A

CENP-A

131
Q

CENP-A is a nucleosome that acts as ___ for kinetochore proteins

A

scaffolds

132
Q

protein complex that holds sister chromatids together during metaphase

A

cohesin

133
Q

at anaphase of mitosis, cohesin is ___ and sister chromatids are ___

A

enzymatically cleaved
released from each other

134
Q

at anaphase I of meiosis, cohesin along ___ is enzymatically cleaved but cohesin at ___ is not enzymatically cleaved

A

chromosome arms
centromeres

135
Q

in anaphase I, mitotic-specific subunit interacts with the protein ___ which protects cohesin from degradation

A

shugoshin

136
Q

after entry into metaphase II, ___ is removed and ___ is degraded

A

shugoshin
centromeric cohesin

137
Q

artificial chromosomes require these three key elements

A
  1. centromeres
  2. telomeres
  3. origins of replication
138
Q

without a centromere, there are ___

A

segregation errors

139
Q

without a telomere, there are ___

A

degradation errors if linear

140
Q

yeast fused chromosome consists of giant ___ fusion of all ___ normal yeast chromosomes

A

11.8Mb
16

141
Q

synthetic chromosomes ___ from artificial chromosomes

A

differ

142
Q

DNA in synthetic chromosomes is ___

A

entirely man made

143
Q

DNA in artificial chromosomes is ___

A

pieced together from yeast chromosomes

144
Q

synthetic chromosomes include ___ on corresponding yeast chromosome

A

all genes present

145
Q

artificial vectors usually have a ___yeast gene

A

single protein-coding

146
Q

fused and synthetic chromosomes help study ___ that support life

A

minimal genome components

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