Ch 2: Chromosomes and Cellular Reproduction (BIO 375 - Genetics) Flashcards

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1
Q

karyotype

A

complete set of an individual’s chromosomes; an image of a set of chromosomes (humans have 46 chromosomes, and 23 homologous pairs)

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2
Q

autosomes

A

any chromosome that is not a sex chromosome

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3
Q

chromosomes

A

thread like structures that carry genetic information

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4
Q

prokaryotes

A

single circular molecule of DNA with no end to chromosome; unicellular organism with simple cell structure; divided into eubacteria or archaea; reproduce through binary fission (chromosome replicates and cell divides)

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5
Q

eukaryotes

A

have multiple linear chromosomes composed of DNA and histone proteins packed like chromatin, where the chromosomes have identifiable ends; compartmentalized cell structure with components bounded by intracellular membranes; can be unicellular or multicellular

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6
Q

diploid

A

carry two sets of genetic information

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7
Q

haploid

A

single set of chromosomes; one copy of each gene

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8
Q

homologous chromosomes

A

alike in structure and size, each carrying genetic information for the same set of hereditary characteristics (except sex chromosomes); one chromosome of the pair is a maternal chromosome and the other is a paternal chromosome

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9
Q

centromere

A

region of chromosome where spindle fibers attach during cell division

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10
Q

telomeres

A

natural ends of a linear chromosome that protect and stabilize the chromosome ends

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11
Q

origins of replication

A

sites where DNA synthesis begins; sister chromatids

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12
Q

cell cycle

A

life cycle of a cell between cell divisions where progression through the cycle is regulated at checkpoints (key transition points)

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13
Q

phases of cell cycle

A
  1. Interphase (G1/G0, G1/S checkpoint, S, G2, G2/M checkpoint)
  2. Mitosis (Prophase, Metaphase, Anaphase, Telephase)
  3. Cytokinesis (cell division)
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14
Q

interphase

A

period between cell divisions (where cell grows, develops, and functions); nuclear membrane is present and chromosomes are relaxed

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15
Q

G1

A

Gap 1: cell growth; unduplicated chromosomes/chromatin

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16
Q

G0

A

Stasis, non-dividing phase

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17
Q

S

A

Synthesis: DNA duplicates/is synthesized

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18
Q

G2

A

Gap 2: mitosis preparation; duplicated chromosomes

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19
Q

prophase

A

chromosomes condense; each chromosome possesses two chromatids; mitotic spindle forms

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20
Q

metaphase

A

chromosomes line up on metaphase plate

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21
Q

anaphase

A

sister chromatids separate and move toward opposite poles

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22
Q

telophase

A

chromosomes arrive at spindle poles; nuclear membrane reforms and chromosomes relax

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23
Q

number of chromosomes per cell

A

equivalent to number of functional centromeres

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24
Q

number of DNA molecules per cell

A

equivalent to twice the number of chromosomes IF sister chromatids are present; if NO sister chromatids are present then equivalent to number of chromosomes

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25
Q

mitosis

A

asexual reproduction; increase in cell numbers; produces identical daughter cells; occurs in most cells; one division of nucleus

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26
Q

meiosis

A

sexual reproduction; begins in specialized gametic stem cells; produces unique haploid progeny cell; two divisions of nucleus (meiosis I and meiosis II)

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27
Q

meiosis I

A

reductional division; a diploid cell divides and forms two haploid cells (halving chromosomal number); introduces genetic variation

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28
Q

prophase I

A

chromatin condenses into chromosomes; nuclear membrane breaks down; homologous chromosomes pair… occurs in 5 substages: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis

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29
Q

leptotene

A

chromosomes condense

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30
Q

zygotene

A

close pairing and association of homologous chromatin; forms a bivalent or tetrad; where synapsis begins

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31
Q

pachytene

A

synaptonemal complex develops between homologues; crossing over occurs

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32
Q

crossing over

A

exchange of genetic information between nonsister chromatids

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33
Q

diplotene

A

centromeres of homologues move apart and homologues remain attached at chiasmata

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34
Q

diakinesis

A

centromeres continue to separate, but chromosomes are still attached at chiasmata

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35
Q

metaphase I

A

homologous pairs of chromosomes line up along metaphase plate; chiasmata are lined up on metaphase plate

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36
Q

anaphase I

A

homologous chromosomes separate and move toward opposite poles

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37
Q

telophase I

A

chromosomes arrive at spindle poles and cytoplasm divides; nuclear membrane reforms; chromosomes decondense to chromatin; two haploid cells are produced; priority on cytokinesis so the “reversal of prophase I” is not as regulated and may vary or not always occur in process

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38
Q

meiosis II

A

equational division (halves amount of genetic material); begins with haploid cells; individual chromosomes line up on equatorial plate -> sister chromatids pull apart and move to opposite poles -> cytokinesis; steps: prophase II, metaphase II, anaphase II, telophase II; gametes remain in G0 upon completion until fertilization or cell death

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39
Q

prophase II

A

chromosomes recondense

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40
Q

metaphase II

A

individual chromosomes line up on equatorial plate

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41
Q

anaphase II

A

sister chromatids separate and move to opposite poles

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42
Q

telophase II

A

chromosomes arrive at spindle poles and cytoplasm divides

43
Q

consequences of meiosis

A

crossing over and recombination produce nonidentical sister chromatids (rearranges linked loci and produces genetic variation)’ independent assortment of chromosomes produces variation

44
Q

recombination

A

creating new combinations of alleles on a chromatid

45
Q

crossing over shuffles

A

alleles on same chromosome into new combinations

46
Q

random distribution of maternal/paternal chromosomes shuffles

A

alleles on different chromosomes into new combinations

47
Q

fertilization

A

two haploid gametes fuse and restore chromosome number to original diploid value; sperm head enters the secondary oocyte where meiosis II occurs to form a mature ovum… haploid nuclei merge to form a diploid zygote

48
Q

spermatogenesis

A

begins at puberty; takes appx. 64 days; spermatogonium (gametic stem cells of males) differentiate then undergo meiosis I and II to produce sperm

49
Q

oogenesis

A

begins 4 months after fertilization; takes 12-50+ years; oogonium (gametic stem cells of females) differentiate then undergo meiosis I and II to produce ovum

50
Q

identification of chromosomes

A

by size and location of centromere

51
Q

short arm

A

p arm; the segments of the chromosome above centromere

52
Q

long arm

A

q arm; segments of chromosome below the centromere

53
Q

number of chromatin

A

(approximately) number of DNA molecules

54
Q

metaphase to anaphase, metaphase II to anaphase II

A

number of chromosomes doubles

55
Q

metaphase I to anaphase I

A

number of chromosomes remains the same

56
Q

middle prophase I

A

(leptotene) chromosomes condense and spindles form

57
Q

late prophase I

A

(zygotene, pachytene, diplotene, diakinesis) homologous chromosomes pair; crossing over takes place and nuclear membrane breaks down

58
Q

synaptonemal complex

A

molecular glue holding chromatin of homologous chromosomes together; reduces chances of unequal crossing over

59
Q

bivalent

A

2 chromosomes

60
Q

tetrad

A

4 chromatids

61
Q

unequal crossing over

A

Misalignment of the two DNA molecules during crossing over, resulting in one DNA molecule with an insertion and the other with a deletion; unequal parts of chromosome exchange during crossing over, resulting in gain or loss of DNA

62
Q

chiasmata

A

points where chromosomes participated in crossing over and are still “stuck together” / touching one another

63
Q

cytokinesis

A

when DNA decreases / halves

64
Q

crossing over leads to

A

recombination

65
Q

linked loci

A

genes that are physically joined together on same piece of chromosome

66
Q

spermatogenesis produces

A

4 mature gametes (sperm)

67
Q

oogenesis produces

A

1 mature gamete (ovum)

68
Q

independent assortment

A

different combinations of chromosomes depending on how chromosomes (maternal and paternal) align/separate in meiosis I and II

69
Q

gametogenesis

A

process of making gametes

70
Q

spermatogenesis cycle

A

occurs in waves for groups of cells

71
Q

oogenesis cycle

A

all oogenium are converted to primary oocytes until 7 months after fertilization (when they then die)… then the primary oocytes undergo cycle in waves

72
Q

unequal distribution of cytoplasm between ovum and polar body

A

so the ovum has nutrients for the zygote/developing embryo until it fuses with the uterine lining

73
Q

secondary oocyte

A

the cell that is ovulated if no sperm is present; product of meiosis I of primary oocyte; are 1n

74
Q

ovum

A

formed from meiosis II ONLY if there is contact with sperm

75
Q

spermatogonium

A

starting gametic stem cells of spermatogenesis; are 2n

76
Q

primary spermatocyte

A

product of differentiation of spermatogonium; produced after mitosis; are 2n

77
Q

secondary spernatocyte

A

product of meiosis I of primary spermatocytes; are 1n

78
Q

spermatids

A

product of meiosis II of secondary spermatocytes; are 1n

79
Q

sperm

A

matured spermatids after G1; are 1n

80
Q

oogonium

A

starting gametic stem cells of oogenesis; are 2n

81
Q

primary oocyte

A

product of differentiation of oogonium; produced after mitosis; are 2n

82
Q

first polar body

A

the other product of meiosis I of primary oocyte; are 1n but with double the chromosomal number

83
Q

ovum

A

product of meiosis II of secondary oocyte if contact is made with sperm; are 1n

84
Q

second polar body

A

the other product of meiosis II of secondary oocyte if contact is made with sperm; are 1n but with double chromosomal number

85
Q

(mitosis) G1

A

2n number of DNA and chromosomes

86
Q

(mitosis) S

A

4n number of DNA and 2n number of chromosomes

87
Q

(mitosis) G2

A

4n number of DNA and 2n number of chromosomes

88
Q

(mitosis) P

A

4n number of DNA and 2n number of chromosomes

89
Q

(mitosis) M

A

4n number of DNA and 2n number of chromosomes

90
Q

(mitosis) A

A

4n number of DNA and number of chromosomes

91
Q

(mitosis) T

A

2n number of DNA and number of chromosomes

92
Q

(meiosis) G1

A

2n number of DNA and number of chromosomes

93
Q

(meiosis) S

A

4n number of DNA and 2n number of chromosomes

94
Q

(meiosis) G2

A

4n number of DNA and 2n number of chromosomes

95
Q

(meiosis) PI

A

4n number of DNA and 2n number of chromosomes

96
Q

(meiosis) MI

A

4n number of DNA and 2n number of chromosomes

97
Q

(meiosis) AI

A

4n number of DNA and 2n number of chromosomes

98
Q

(meiosis) TI

A

2n number of DNA and n number of chromosomes

99
Q

(meiosis) PII

A

2n number of DNA and n number of chromosomes

100
Q

(meiosis) MII

A

2n number of DNA and n number of chromosomes

101
Q

(meiosis) AII

A

2n number of DNA and 2n number of chromosomes

102
Q

(meiosis) TII

A

n number of DNA and number of chromosomes

103
Q

(meiosis) after meiosis

A

n number of DNA and number of chromosomes