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23 Cards in this Set
- Front
- Back
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karyotope
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the number and types of chromosomes present in an individual
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homologs (homologous chromosomes)
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the same type of chromosome
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allele
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different version of the same gene
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haploid number
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the number of distinct chromosomes present
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ploidy
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this indicates the number of each type of chromosome that is present.
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haploid
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organisms whose cells contain just one of each type of chromosome
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Diploid
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those whose cells contain two versions of each type of chromosome
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Meiosis I
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the diploid parent cell produces two haploid daughter cells. the homologs separate and go to each daughter cell
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Meiosis II
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the sister chromatids of each chromosome separate and go to different daughter cell.
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Meiosis I has 5 phases
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1. Early Prophase I
2. Late Prophase I 3. Metaphase I 4. Anaphase I 5. Telophase I |
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Early Prophase I
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homolog pairs come together in a pairing process called synapsis. The chromatids are called non sister chromatids here.
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Late Prophase I
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the non sister chromatids begin to separate. crossing over of the homologs begins where chiasmata are formed
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Metaphase I
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The tetrads line up at the Metaphase plate
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Anaphase I
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The paired homologs separate and begin to migrate at other ends of the cell
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telophase I
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the homologs finish migrating, and the cells divide, called cytokinesis
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Meiosis II has 4 phases
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1. Prophase II
2. Metaphase II 3. Anaphase II 4. Telophase II |
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Prophase II
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spindle apparatus forms and one spindle fiber attaches to the centromere of each sister chromatid
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Metaphse II
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Replicated chromosomes line up at the metaphase plase
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Anaphase II
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Sister chromatids separate, the resulting daughter chromosomes begin moving to opposite ends of the cell
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Telophase II
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Chromosomes arrive at opposite ends of the cell. nuclear envelope forms, and each cell undergoes cytokinesis.
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genetic recombination
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a form of crossing over. it increases genetic variability of gametes produced by meiosis beyond that produced by a random assortment of chromosomes.
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nondisjunction
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meiotic error. if both homologs or both sister chromatids move to the same pole of the parent cell, the products will be abnormal. if this happens, then there will be an extra copy of a chromosome, and two gametes will lack chromosomes-which results in down syndrome.
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Aneuploidy
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A cell with too few or too many chromosomes.
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