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24 Cards in this Set
- Front
- Back
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What are the four differences between sexual and asexual reproduction?
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1. Joining of sex cells 2. Number of parents 3. identicalness of offspring 4. mechanism
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Heredity
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transition of traits from one generation to the next
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Genetics
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scientific study of heredity variation
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Karyotype
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organization of a cell’s chromosomes by number, size and type
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Interphase I
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DNA replication occurs and centromeres link sister chromatids. first stage of meiosis I
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Prophase I
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Homologous pairs partner up (one copy from mom and one from dad). Symapsis attaches homologous pairs together into a tetrad. Crossing over occurs, simple fibbers form and nuclear membrane beings to disappear. second stage of meiosis I.
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Metaphase I
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Chromosomes line up in straight lines within their homologous pairs along the metaphase plate. Thirst stage of meiosis I.
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Anaphase I
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Sister chromatids remain attached at centromere, homologous pairs separation, sister chromatids move as a unit to the poles. Fourth stage of meiosis I.
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Telophase I and Cytokinesis
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Cells split (just like telophase in mitosis). NOT followed by interphase. Fifth stage of meiosis I.
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Prophase II
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spindles form. First stage of meiosis II and sixth stage of meiosis
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Metaphase II
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chromosomes line up in middle again in a straight line. Second stage of meiosis II and seventh stage of meiosis
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Anaphase II
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Centromeres break, sister chromatids separation and move to poles. Third stage of meiosis II and eighth stage of meiosis.
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Telophase II and Cytokinesis
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Chromosomes turn back into chromatin, 4 daughter cells are produces, sex cells have been created. Fourth stage of meiosis II and ninth (and final) stage of meiosis
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What are the three sources of variation in meiosis?
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Independent Assortment, Crossing over, random fertilization
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Independent Assortment
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genes sort seperately into gametes
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What is the progression of the number of cells in meiosis?
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The progression is that we start with 4 chromosomes in one cell and end up with 2 chromosomes in each of 4 cells.
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Crossing Over
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During Prophase I homologous chromosomes join tightly and chromosomes can exchange genes
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Random Fertilization
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so many eggs and so many sperm that there are 64 trillion possibilities even without crossovers
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Oogenesis
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production of ova (mature eggs), occurs in ovaries
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Oogonia
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stem cells that make eggs
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What is the process of oogenesis?
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Stem cells begin meiosis, stop at prophase II and hang out there until the follicle is stimulated to grow. It will completely meiosis I and starts to meiosis II where it will become a secondary oocyte and stop, completing meiosis II when it is penetrated by a sperm
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Spermatogenesis
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production of mature sperm, occurs in somniferous tubules in testes
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Spermatogonia
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stem cells that maker sperm
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What are the 3 differences between spermatogenesis and oogenesis?
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1. in O meiotic divisions are unequal while they are equal in S 2. at birth O have all the eggs but S go through meiosis all through a mans life 3. O has resting periods while S is uninterrupted.
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