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31 Cards in this Set
- Front
- Back
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What is Meiosis? |
A special form of cell division in reproductive cells that reduces the chromosome number from the diploid to the haploid as gametes are formed |
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Is interphase a a stage of meiosis? |
no |
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What is the main event of interphase? |
DNA Replication |
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Prophase 1 |
-chromosome coils into chromosomes -nuclear membrane disappears -nucleolus disappears -centrioles (animal cells) move apart -spindle fibers form |
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what do spindle fibers do? |
hook on to the chromosomes and move them around |
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what is synapsis? |
the pairing of two homologous pairs |
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what is a pair of homologous chromosomes called? |
tetrad |
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What is crossing-over? |
when portions of chromatids break off and attach to adjacent chromatids on the homologous chromosome, allowing for exchange of genetic material between maternal and paternal chromosomes. |
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Metaphase 1 |
tetrads line up at the equator, centromeres of each chromosome are attached to the spindle fibers |
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Anaphase 1 |
one chromosome from each homologous pair is pulled towards opposite poles by spindle fibers, centromeres don't split and chromatids remain together, this is the stage where the chromosome number is reduced from the diploid to the haploid |
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Telephase 1 |
-cytokinesis occurs |
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what is the end result of meiosis 1? |
2 cells each with a haploid nucleus |
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does dna replication precede in meiosis 2? |
no |
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Prophase 2 |
-chromosomes become visible -spindle fibers attach to centromeres |
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does synapsis occur in prophase 2? Why or Why not? |
no, because there is one chromosome from each homologous pair in opposite cells--they can't physically pair up |
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Metaphase 2 |
-chromosomes line up at the equator-but not in pairs |
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How does Metaphase 2 compare with Metaphase in mitosis? |
They are the same |
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Anaphase 2 |
-Centromeres split -Chromatids are pulled towards the poles |
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How does anaphase 2 compare to anaphase in mitosis |
They are the same |
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Telaphase 2 |
-cytokinesis -nuclei and nucleolus reappear |
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what is the end results of meiosis 2? |
4 cells each with haploid chromosome number |
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Meiosis in males is called? |
spermatogenesis |
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how many sperm cells are produced in meiosis in males? |
4 equally sized sperm cells |
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does the cytoplasm divide evenly-males meiosis? |
yes |
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what is meiosis in females called? |
oogenesis |
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_____cells--but only _____becomes an egg |
4,1 |
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does the cytoplasm divide evenly-females? |
no because the egg receives most of the cytoplasm |
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what are the three other cells called? |
polar bodies |
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why do the three polar bodies end up dying |
they receive very little cytoplasm |
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doe oogenesis happen before or after birth? |
before birth |
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at birth an __________ has all of the egg cells it will ever have |
ovary |
