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Meiosis
Biology ch 12
| Term | Definition |
|---|---|
| asexual reproduction | involves one parent and produces a clone |
| sexual reproduction | involves two parents |
| examples of asexual reproduction | binary fission, budding, fragmentation, |
| Karyotype | used to identify sex or aneuploidy (abnormal number of chromosomes) |
| chrosomes 1-22 | autosomes |
| chrosome 23 | sex chrosomes |
| homologous chrosomes | similar in sturcture and carry the same types of genes, one from each parent |
| diploid | contain a full set of chrosomes form both parents |
| stomatic cells | all body cells: skin, nerve |
| haploid | cells that contain 1/2 the full set of chrosomes |
| gametes | reproductive cells; egg and sperm |
| how many divisions occur in meiosis | 2 |
| in what cells does meiosis occur in | sex cells |
| how many chromosomes end up in the daughters cells | half the amount |
| how many daughter cells result in meiosis | 4 |
| Spermatogenesis | results in 4 equal sperm cells |
| oogenesis | resluts in 1 large egg and 3 polar bodies |
| interphase | longest phase, contians G1, S, G2 |
| Prophase 1 | snapsis occurs, crosing over occurs, spindle fibers form. chrosomes condense |
| synapsis | homologous chrosomes come together to form a tetrad |
| tetrad | two chrosomes or for chromatids |
| crossing over | segments of nonsister chromatids break and reattach to the other chromatid, causes genetic recombiantion |
| chiasmata | where chrosomes touch each other and exchange genes |
| metaphase 1 | shortest phase, tetrads align, indepnednet assortment occurs |
| anaphase 1 | homologous chrosomes seperate and move towards the poles, sister chromatids remaind attached at their centromeres |
| telophase 1 | each pole now has haploid set of chrosomes, cytokinesis occurs and two haploid daughter cells are formed |
| interkinesis | short period of time between meiosis 1 and 2 |
| prophase 2 | nucleus and nucleolus dissapear, chrosomes condense, spindle forms |
| metaphase 2 | chrosomes line up at equator |
| anaphase 2 | sister chromatids seperate |
| telophase 2 | nuclei and nucleoli reform, spindle disappears, cytokinesis occurs, 4 haploid daughter cells are produced |
| independent assortment | chrosomes assort independently from one another during meiosis |
| random fertilization | whichever gamete is involved in actual fertilization determines the genes of the offspring |
| nondisjunction | occur when homologous chrosomes fail to seperate at meiosis 1 or when chromatids fail to separate at meiosis 2 |