Chapter 13 Flashcards

1
Q

autosomes

A

any chromosomes that is not a sex chromosome

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2
Q

homologs

A

contain the same genes in the
same position along the chromosome; contain different versions of genes

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3
Q

locus

A

position of a gene

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4
Q

diploid

A

two sets of chromosomes
- one from each parent

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5
Q

what does a ploidy indicate

A

number of complete chromosomes sets it contains

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6
Q

what does meiosis convert cells to

A

diploid to haploid

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7
Q

what is the difference between haploid and diploid

A

diploid cells have 2 pairs of homologous sets of chromosomes and haploid only have 1 set of chromosomes

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8
Q

zygote

A

has a diploid chromosome number,
one set from each parent
- fertilized egg

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9
Q

what is the importance of meiosis

A
  • genetic variation
  • prevents chromosome # from doubling
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10
Q

what are the phases of meiosis 1

A

Early prophase I
Late prophase I
Metaphase I
Anaphase I
Telophase I

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11
Q

late prophase 1

A
  • homologs begin to separate but remain attached at points called chiasmata
  • crossing over occurs between homologous non sister chromatids
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12
Q

chiasmata

A

where genetic material is exchanged

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13
Q

synapsis

A

when chromosomes first cross over

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14
Q

metaphase 1

A
  • paired of homologs line up at metaphase plate randomly
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15
Q

anaphase 1

A

homologs separate and move to opposite ends of cell

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16
Q

telophase 1

A

homologs finishing moving to poles of cell

17
Q

what happens at the end of meiosis 1

A

cytokinesis and results in daughter cells with only one chromosome of each homologous pair

18
Q

what are the phases of meiosis 2

A

Prophase II
Metaphase II
Anaphase II
Telophase II

19
Q

what does not occur in meiosis 2

A

no chromosomes replication occurs

20
Q

what does meiosis 2 only work with

A

sister chromatids

21
Q

what does meiosis 2 result in

A

four haploid daughter cells with each type of chromosome
- four haploid cells with un replicated chromosomes

22
Q

random fertilization

A

combination of each
unique sperm with each unique egg increases genetic
variability.

23
Q

when does independent orientation occur

A

at metaphase 1

24
Q

independent orientation

A
  • Each pair of chromosomes independently aligns at the
    cell equator.
  • equal probability of the maternal or
    paternal chromosome facing a given pole
25
what could happen if things go wrong in meiosis
- chromosomes may not get pulled apart correctly - both homologs or sister chromatids could move to same pole - products will be abnormal
26
nondisjunction
meiotic error that results in abnormal gametes - both homologs or sister chromatids could move to same pole
27
how do mistakes occur
nondisjunction results in gametes that - Contain an extra chromosome (n + 1) - Lack one chromosome (n − 1)
28
what type of gametes lead to trisomy
n+1 - too many chromosomes
29
what type of gametes lead to monosomy
n-1
30
aneuploid
Cells with too many or too few of a chromosome
31
what causes mistakes to occur
- random errors - maternal age - egg devolvement
32
when do primary oocytes enter during embryonic devolvement
meiosis 1
33
where do oocytes rest until sexual maturation
prophase 1
34
what can also cause a error in meiosis
longer time period occurs until ovulation, greater the chances of something going wrong
35
mitosis vs meiosis
- meiosis is followed by two consecutive cell divisions and mitosis is followed by only 1 cell division - each gametes in meiosis is genetically different from one another