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23 Cards in this Set
- Front
- Back
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What is the purpose of meiosis?
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Transmit genes in an orderly fashion by creation of gametes
Go from diploid to haploid (seperate homologous pairs) Shuffle genes for variation |
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What is a karyotype?
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Visual picture of condensed chromosomes
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What is a homolog?
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A pair of chromosomes that contain the same genes at the same loci (alleles for the genes may be different)
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What is a gene?
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Inheritable unit of genetic information (DNA) that codes for a specific protein or trait
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What is an allele?
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A different version of a gene
i.e. gene for pea flowers has white allele and purple allele |
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Diploid vs. Haploid
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Diploid/2N = having full complement (2 sets) of chromosomes; one from each parent
Haploid/N = having only 1/2 complement ( 1 set) of chromosomes |
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What is synapsis?
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During prohpase I, homologs find each other and pair up
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What is "crossing over"?
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When homologs pair up, they get so close that they stick to each other; they often swap pieces of their chromatids; one way to get genetic variation
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What is the difference between DNA replication for Mitosis (mt) and Meiosis (me)?
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mt = S of interphase
me = S of interphase |
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Number of divisions?
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mt = 1
me = 2 |
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Synapsis of homologous chromosomes?
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mt = no
me = yes; prophase I |
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Number of daughter cells and genetic composition?
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mt = 2; genetically identical to each other and parent cell; all diploid
me = 4; genetically different to each other, all haploid |
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Role in the animal body?
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mt = growth/repair
me = create gametes for reproduction |
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What is the differences between Meiosis I and II in interphase?
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Meiosis 1 = G1/S/G2
Meiosis 2 = n/a |
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Prophase?
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Meiosis 1 = DNA condensed as chromosomes nuclear membrane breaks down centrosomes migrate spindle fibers form
synapsis/crossing over of homologs Meiosis 2 = DNA condensed centrosomes migrate spindle fibers form |
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Metaphase I and II?
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Meiosis 1 = homologous pairs line up on plate (independent assortment)
spindles attach to each kinetochore Meiosis 2 = chromosomes line up individually with centromeres on plate spindle fibers attach to each kinetochore |
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Anaphase I and II?
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Meiosis 1 = homologous pairs pulled apart/to opposite poles (law of segragation)
Meiosis 2 = sister chromatids pulled apart/to opposite poles (now called chromosomes) |
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Telophase/Cytokinesis I and II?
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Meiosis 1 = same events of mitosis, but now the two cells are haploid, non-identical
Meiosis 2 = same events of mitosis; each cell from meiosis I has gone through M-II, so now there are 4 non-identical haploid cells |
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How is meiosis II similar to mitosis?
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In both mitosis and meiosis II, sister chromatids are being seperated, so chromosomes line up in the same fashion on the metaphase plate, and sister chromatids are pulled apart during anaphase
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If 2n=14, how many chromosomes will be present in somatic cells?
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14
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How many chromosomes will be found in the gametes?
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7
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If n=14, how many chromosomes will be found in diploid somatic cells?
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28
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For the human. 2n=___ & n=___
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46;23
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