Chapter Three: Chromosomes Flashcards

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1
Q

the first human genetic disorder attributable to an abnormal number of chromosomes rather than a gene mutation

A

down syndrome

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2
Q

chromosomes transmit ___

A

genetic information

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3
Q

the ___ and ___ of genetic material is important for normal development

A

type and amount

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4
Q

genes reside in ___ in the ___

A

chromosomes
nucleus

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5
Q

the first observations of fertilization of nuclei occurred with ___ looking at ___

A

the naked eye
frog and sea urchin eggs and sperm

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6
Q

from observing the fusion of nuclei in frog and sea urchin eggs, scientists concluded that ___

A

something in the nucleus must contain hereditary material

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7
Q

in the 1880s, ___ and ___ were highly improved, and ___ could be visualized in the ___ and followed through ___

A

microscopy
staining techniques
chromosomes
nucleus
cell division

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8
Q

nuclear division that generates two daughter cells containing the same number and type of chromosomes as parent cell

A

mitosis

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9
Q

nuclear division that generates gametes (egg and sperm) containing half the number of chromosomes found in other cells

A

meiosis

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10
Q

body cells are ___and gametes are ___

A

diploid
haploid

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11
Q

diploid human cells have ___ chromosomes

A

46

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12
Q

haploid human cells have ___ chromosomes

A

23

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13
Q

the union of haploid gametes to produce diploid zygotes

A

fertilization

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14
Q

for each pair of chromosomes, zygotes have one from ___ and one from ___

A

mom
dad

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15
Q

how many cells are in an average adult human

A

100 trillion

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16
Q

to get from 1 to 100 trillion cells, ___ rounds of cell division are needed

A

60

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17
Q

metaphase chromosomes can be classified by ___, ___, and ___

A

size, banding pattern, and centromere position

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18
Q

location where sister chromatids are attached

A

centromere

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19
Q

centromere is in the middle of sister chromatids

A

metacentric chromosome

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20
Q

centromere is near one end of sister chromatids

A

Afrocentric chromosome

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21
Q

centromere is at the end of sister chromatids

A

telocentric chromosome

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22
Q

identical copies of a replicated chromosome

A

sister chromatids

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23
Q

chromosomes that contain the same set of genes, but can have different alleles for some genes

A

homologs/homologous chromosomes

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24
Q

chromosomes that carry completely unrelated sets of genes

A

nonhomologs/nonhmologous chromosomes

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25
Q

there are about ___ genes in the human genome, and about ___ genes per chromosome

A

20,000
1,000

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26
Q

___ of human DNA codes for something

A

1.5%

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27
Q

micrograph of stained chromosomes arranged in homologous pairs

A

karyotype

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28
Q

homologous chromosomes have the same ___, ___, and ___

A

size, shape (centromere location), and banding

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29
Q

the study of genetic anomalies

A

cytogenetics

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30
Q

every species has a characteristic number of ___

A

chromosomes

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31
Q

all chromosomes except X and Y

A

autosomes

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32
Q

unpaired X and Y

A

sex chromosomes

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33
Q

chromosomes are made of ___, ___, and ___

A

DNA, histone protein, and non-histone protein

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34
Q

a long thread primarily made of DNA with some protein scaffolding, what chromosomes usually exist as

A

chromatin

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35
Q

chromatin only duplicated and condenses into visible chromosomes when ___

A

cell division is about to occur

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36
Q

duplicated chromosomes (chromatids) are joined at the ___

A

centromere

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37
Q

a repeating pattern of cell growth and division

A

cell cycle

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38
Q

passes of the cell cycle

A

G1
S
G2
mitosis
cytokinesis

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39
Q

period of cell growth and chromosome duplication between divisions

A

interphase

40
Q

microtubule organizing center near the nuclear envelope

A

centrosome

41
Q

centrosome is also called the ___

A

“MTOC” (microtubule organizing center)

42
Q

___ come from the centrosome

A

microtubules / spindle fibers

43
Q

the centrosome divides to form ___

A

two centrioles

44
Q

most of cell growth occurs during ___ and ___

A

G1 and G2

45
Q

some terminally differentiated cells stop dividing and arrest in ___ stage

A

G0

46
Q

___ and ___ stop in G0

A

mature neurons
muscle cells

47
Q

chromosomes replicate to form sister chromatids during ___

A

S phase

48
Q

which phase do most defects happen that cause cancers

A

G1

49
Q

when do chromosomes form from chromatin

A

end of G2, right before mitosis

50
Q

3 steps in prophase

A
  1. chromosomes condense and become visible
  2. centrosomes move apart toward opposite poles
  3. nucleoli begin to disappear
51
Q

2 steps of prometaphase

A
  1. nuclear envelope breaks down
  2. spindle forms and sister chromatids attach to microtubules from opposite centrosomes
52
Q

2 steps of metaphase

A
  1. chromosomes align on the metaphase plate with sister chromatids facing opposite poles
  2. forces pushing and pulling chromosomes to or from each pole are in balanced equilibrium keeping chromosomes in place
53
Q

2 steps of anaphase

A
  1. centromeres of all chromosomes split simultaneously
  2. kinetochore microtubules shorten and pull separate sister chromatids to opposite poles
54
Q

4 steps of telophase

A
  1. nuclear envelope forms around each group of chromatids
  2. nucleoli re-form
  3. spindle fibers disappear
  4. chromosomes uncoil and reform as chromatin
55
Q

three kinds of microtubules and their functions

A
  1. astral = anchor to cell membrane
  2. kinetochore = push against chromosome
  3. polar = pull chromosome toward centrosome
56
Q

cytokinesis begins during ___ but is not completed until after ___

A

anaphase
telophase

57
Q

cytokinesis

A

cytoplasm of parent cell split into two daughter cells with identical nuclei

58
Q

in animal cytokinesis, a ___ contracts to form ___

A

contractile ring
cleavage furrow

59
Q

in plant cytokinesis, a ___ forms near the equator of the cell

A

cell plate

60
Q

in all cytokinesis, ___ are distributed to each daughter cell

A

organelles

61
Q

does cytokinesis always occur after mitosis?

A

NO

62
Q

a cell with multiple nuclei

A

syncytium

63
Q

a syncytium is a result of ___

A

cytokinesis not occurring

64
Q

there are ___ in the cell cycle that have to occur before the cell moves on to the next stage

A

checkpoints

65
Q

make up the vast majority of cells in an organism

A

somatic cells

66
Q

somatic cells are either in stage ___ or ___

A

G0
actively going through the cell cycle

67
Q

precursors to gametes

A

germ cells

68
Q

germ cells are set aside during ___

A

embryogenesis

69
Q

germ cells become incorporated into ___

A

reproducing organs

70
Q

only cells that undergo meiosis to produce haploid gametes

A

germ cells

71
Q

meiosis has ___ of cell division

A

two rounds

72
Q

in meiosis, chromosomes duplicate ___ and nuclei divide ___

A

once
twice

73
Q

meiosis one reduces chromosomes from ___ to ___

A

2n
n

74
Q

meiosis two produces ___

A

four haploid nuclei

75
Q

meiosis one separates ___, meiosis two separates ___

A

chromosomes
sister chromatids

76
Q

in meiosis one, homologs ___, ___ and then ___

A

pair, cross over, segregate

77
Q

___ remain intact through meiosis one

A

sister chromatids

78
Q

in meiosis one, maternal and paternal homologs ___ and create new combinations of alleles

A

recombine

79
Q

homologous chromosomes pair together in prophase one and are held together by ___

A

synaptonemal complex

80
Q

crossing over occurs during ___ resulting in ___ of genetic material

A

prophase one
recombination

81
Q

the outer chromatids of homologous pairs are ___ and the inner chromatids are ___

A

parental
recombinant

82
Q

after recombination, the synaptonemal complex ___ and chromatids in each ___ become visible

A

dissolve
tetrad

83
Q

in metaphase one and anaphase one, ___ are separated

A

homologs

84
Q

in metaphase one and anaphase one, ___ do not divide and ___ do not separate

A

centromeres
sister chromatids

85
Q

meiosis one is a ___ division

A

reductional

86
Q

phase after meiosis one in which no chromosomal duplication takes place

A

interkinesis

87
Q

during meiosis two, ___ separate

A

sister chromatids

88
Q

in meiosis two, haploid nuclei progress through a process similar to ___ to create ___

A

mitosis
four haploid daughter cells

89
Q

meiosis two is an ___ division

A

equational

90
Q

four haploid cells that result from meiosis two each have unique ___

A

genomes

91
Q

homologs of a chromosome pair do not separate during meiosis one

A

nondisjunction

92
Q

nondisjunction may result in ___ or ___

A

inviable gametes or embryos
abnormal chromosome numbers in viable individuals

93
Q

independent assortment of nonhomologs creates different combinations of alleles in ___

A

gametes

94
Q

crossing-over between homologs creates different combinations of alleles in ___

A

each chromosome

95
Q

two ways meiosis contributes to genetic diversity

A

independent assortment of nonhomologs
crossing-over between homologs

96
Q

in 1903, ___ determined that chromosomes carry Mendel’s units of heredity

A

Walter Sutton

97
Q

does the movement of chromosomes prove or disprove Mendel’s laws

A

proves