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26 Cards in this Set
- Front
- Back
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Independent Assortment
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(shuffling of chromosomes) random distribution of homologous chromsomes during meiosis
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Crossing-over
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(shuffling of genes) during prophase I, homologous chromosomes pair up forming tetrad and portions of chromosomes (genes) are exchanged
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Random fertilization
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(shuffling of gametes-sex cells) no telling which out of the millions/billions you produce will actually partake in fertilization
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Meiosis
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form of cell division in which the number of chromosomes is halved (haploid)
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Alleles
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different varieties of a particular gene (brown eye allele, blue eye allele)
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Prophase I (diploid)
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Chrosomes condense and become visible. The nuclear envelope dissolves. Homologous chromsomes pair up side by side and crossing-over occurs. Portions of chromatids or homologous pairs are swapped
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Metaphase I
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Chromosomes line up in center of cell. But homologous chromsomes remain side by side.
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Anaphase I
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Homologous chromosomes move to opposite poles of the cell.
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Telophase I and Cytokinesis
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Chromosomes gather at either end and cytoplasm divides. Form 2 haploid cells. *Each new cell contains 1 chromsome from each homologous pair.
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Prophase II (2 haploid)
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Nuclear envelope dissolves and new spindle forms. 2 new cells.
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Metaphase II
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Chromosomes line up along middle.
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Anaphase II
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Centromeres divide and sister chromatids (now called chromosome) split and move to opposite ends
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Telophase and Cytokinesis
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Cytoplasm divides. Nuclear envelope reform. *Results: 4 different haploid cells (aka sex cells)
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Order of stages in meiosis
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Meiosis I:
Prophase I Metaphase I Anaphase I Telophase I and Cytokinesis Meiosis II: Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis |
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How to get the number of combinations of pairs of chromosomes
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2^the number of pairs
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sex chromosomes and autosomes
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Sex chromosome- chromosomes involved in determining sex (1 pair- X & Y chromosomes)
Autosomes- chromosomes not involved in determining sex (22 pairs) |
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homolgous pair
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similar in size, shape, and genetic information (one is from mom, one is from dad)
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Diploid cell and haploid cell
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Diploid cell- (2n=46 in humans) - cell with 2 sets of chromosomes (somatic cells)
Haploid- (n=23 in humans)- cell with one set of chromosomes (gametes) |
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Zygote
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A fertilized egg
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Fertilization and meiosis
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fertilization- fusion of 2 haploid gametes to form a diplid zygote
meiosis- form of cell division in which the number of chromosomes is halved (haploid) |
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Mitosis and meiosis
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Mitosis: results in 2 identical diploid cells
2n | | 2n 2n identical cloves Meiosis: results in 2 haploid cells which contain a mixture of chromosomes from 2 parent gametes, so cannot be identical--> variation 2n | | n n || || nn nn different |
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X and Y chromosomes
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Female-XX Male-XY (humans)
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Deletion
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piece of chromosome breaks off
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Duplication
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chromosome fragment attaches to homologous chromosome which will then have 2 copies of a certain set of genes
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Inversion
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chromosome piece reattaches to original chromosome but in reverse orientation
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translocation
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chromosome piece attaches itself to a nonhomologous chromosome
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