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Genetics > Chapter 4 > Flashcards

Chapter 4 Flashcards

(75 cards)

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1
Q

Anton van Leeuwenhoek

A

Came up with the idea that semen contains spermatozoa (sperm animals)

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2
Q

Chromosomes

A

The self-replicating genetic structures of cells containing the DNA that carries in its nucleotide sequence the linear array of genes

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3
Q

Mitosis

A

nuclear division followed by cell division that results in two daughter cells containing the same number and type of chromosomes as the original parents [somatic (body) cells]/ eukaryotic cells

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4
Q

Meiosis

A

nuclear division that generates egg or sperm cells containing half the number of chromosomes found in other cells within the same organism (gamete)/ sexually reproducing gametes

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5
Q

Haploid (n)

A

gametes and other cells that carry only a single set of chromosomes

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6
Q

Diploid (2n)

A

zygotes and other cells carrying two matching sets

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7
Q

n

A

number of chromosomes in a normal haploid cell

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8
Q

2n

A

number of chromosomes in a normal diploid cell

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9
Q

Sister chromatids

A

two identical halves

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10
Q

centromere

A

where the sister chromatids attach

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11
Q

metacentric

A

centromere is more or less in the middle

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12
Q

acrocentric

A

the centromere is very close to one end

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13
Q

homologous chromosomes

A

chromosomes that match in size, shape and banding

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14
Q

nonhomologous chromosomes

A

chromosomes that carry completely unrelated sets of genetic information (appear in different color)

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15
Q

micrographs of stained chromosomes in homologous pairs decreasing in size to study the chromosomes of a single organism

A

karyotype

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16
Q

autosomes

A

matching pairs of chromosomes (44 in a matching pair)

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17
Q

sex chromosomes

A

unmatched chromosomes that determine the sex of the individual; two distinct chromosomes that provide the basis of sex determination

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18
Q

Walter Sutton

A

one of the earliest cytologist to realize that particular chromosomes carry the information for determining sex

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19
Q

SRY

A

(sex-determining region)
Y-chromosomes-specific gene that is the primary determinant of maleness;
Activates 6 weeks after fertilization and activates testes development which secretes hormones that trigger the development of male sex organs and prevent the formation of female sex organs

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20
Q

Pseudoautosomal regions (PARs)

A

Homologous regions at the two ends of the X and Y chromosome

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21
Q

Heterogametic sex

A

two different sex chromosomes that gives rise to two different types of gametes

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22
Q

chromatin

A

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

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23
Q

envelope composed of two membranes that surrounds the nucleus of eukaryotic cell

A

nuclear envelope

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24
Q

large sphere-shaped organelle visible in the nucleus that plays a key role in the manufacture of chromosomes that function in protein synthesis

A

nucleolus

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25
Chromatid
one of the two copies of a chromosome that exists immediately after DNA replication
26
Cell Cycle
the repeating pattern of cell growth (an increase of size) followed by division (the splitting of one cell into two)
27
M phase
where a small amount of time in the cell cycle where cell is in division
28
interphase
period between division; consists of three parts: G1, synthesis and G2
29
G1 phase (Gap 1 Phase)
lasts from birth of a cell to the onset of chromosome replication--> period where the chromosomes are neither duplication or dividing During this time, the cell achieved most of its growth
30
Synthesis (S phase)
The time when the cell duplicates its genetic material by synthesizing DNA Each chromosome doubles to produce identical sister chromatids attached at the centromere REPLICATION IS CRITICAL in this phase--> genetic material must be copied exactly so that both daughter cells receive identical sets of chromsomes
31
G2 phase (Gap 2 phase)
interval between chromosome duplication and the beginning of mitosis. Cell may grow and it also synthesizes proteins that are essential to the steps of mitosis. Microtubules, crucial for mitosis, becomes visible around the nucleus --> radiate from centrosomes
32
Prophase
Gradual emergence or condensation of individual chromosomes from chromatin
33
Prometaphase
breakdown of the nuclear envelope, which allow the microtubules to invade the nucleus
34
Kinetochore
centromere region of each chromatid that is specialized for conveyance (moving from one place to another). Contains molecular motor--> enables chromosome to slide along the microtubule
35
Kinetochore microtubules
microtubules that extend between a centrosome and the kinetochore of a chromatid; essential for grabbing and pulling chromosomes
36
Metaphase
middle stage; connection of sister chromatids move to opposite spindle poles that cause the chromosome to move toward the middle
37
metaphase plate
imaginary equator halfway between the poles
38
phase where centromeric connections between the sister chromatids of all chromosomes are severed; separation of sister chromatids and forms single chromosomes
Anaphase
39
Phase where spindle fibers begins to disperse and a nuclear envelope forms around the group of chromatids at each pole
Telophase
40
Cytokinesis
Final stage where the elongated parent cell segregates into two smaller independent daughter cells with identical nuclei
41
Contractile rings
In animal cells, the mechanisms that pinches the cell into two equal halves
42
Cell plate
In plant cells, forms near the equator and grows rapidly outward, dividing the cell into two
43
Two or more nuclei in an animal cell
synctium
44
coenocyte
a multi-nucleate plant cell
45
Checkpoints
moments at which the cell evaluates the results of previous steps--allow the sequential coordination of cell cycle events
46
G0 phase
cells stop dividing
47
somatic cells
mitotically dividing and G0-arrested cells
48
germ cells
cells set aside for a specialized role in the production of gametes
49
Meiosis I
the parent nucleus divides to form two daughter nuclei
50
each two daughter nuclei divides resulting in four nuclei
meiosis II
51
Prophase I
homologous recombination occurs before spindle fibers occur
52
Recombinant nodules
structures that appear during prophase I. An exchange of parts between nonsister chromatids occurs at recombination nodules
53
Crossing-over
during meiosis, the breaking of one maternal and one paternal chromosome, resulting in the exchange of corresponding sections of DNA and the rejoining of the chromosome
54
Chaismata
Sites where crossing-over occured
55
metaphase I
phase in which kinetochores of homologous chromosomes attach to microtubules from opposite spindle poles
56
Chiasmata joining homologous chromosomes dissolve, which allows the maternal and paternal homologous to begin to move toward opposite spindle poles. Centromeres do not divide so that the chromosomes moving toward the poles each consist of two chromatids
Anaphase I
57
Nuclear membrane begins to form around the chromosomes that have moved to the poles
Telophase I
58
Reductional Division
number of chromosomes reduced to one-half
59
Interkinesis
brief interphase between meiosis I and meiosis II
60
Prophase II
nuclear envelope breaks down and the spindle apparatus re-forms
61
Equational division
each daughter cell has the same number of chromosomes as the parental cell at the beginning of division
62
How does meiosis contribute to genetic diversity in a population?
1) Different gametes carry a different mix of maternal and paternal chromosomes 2) Reshuffling of genetic information through crossing over during Prophase I, ensures an even greater amount of genetic diversity in gametes
63
Ovum
End product of egg formation in humans; can sustain the early embryo
64
The process that begins when the diploid germ cells in the ovary multiply rapidly by mitosis and produce a large number of primary oocytes which then undergo meiosis
Oogenesis
65
Oogonia
Diploid germ cells in the ovary
66
Meiosis I in primary oocytes
Results in two daughter cells that differ in size (assymetrical division)
67
Secondary oocyte
Larger of the cells that receives over 95% of the cytoplasm
68
Polar body
Smaller of the two daughter cells produced during oogenisis that does not become the primary or secondary oocyte
69
When does oogenesis begin?
In the fetus and after six months of contraception, the fetal ovaries are fully formed and contain about half a million primary ooctyes
70
Spermatogenesis
production of sperm
71
Spermatogonia
diploid germ cells in the testes where spermatogenesis begins
72
spermatocytes
diploid cells produced by mitotic division of spermatogonia
73
Secondary spermatocytes
Produced when primary spermatocytes undergo a symmetrical meiosis I
74
Spermatids
haploid cells produced at the end of meiosis that will mature into sperm
75
Sperm
Haploid male gametes that have whip-like tail and chromosomal material concentrated in their head.

Genetics (15 decks)

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