Meiosis and Chromosomes

Meiosis and Chromosomes - Download 11 Meiosis and...

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Download 11 Meiosis and Chromosomes Principles of Biology BIOL 1543 Greig Roberts, DDS Office: SCEN 417 E-Mail: [email protected]
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2 Mitosis Meiosis Parent cell (before chromosome replication) Chromosome replication Chromosome replication Chromosomes align at the metaphase plate Sister chromatids separate during anaphase Prophase Metaphase Anaphase Telophase Duplicated chromosome (two sister chromatids) Daughter cells of mitosis 2 n 2 n 2 n = 4 A review of mitosis
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3 Chromosomes occur in homologous pairs The somatic (body) cells of each species contain a specific number of chromosomes. Human cells = 46 (23 pairs) of homologous chromosomes. Chromosomes Centromere Sister chromatids The chromosomes of a  homologous pair carry genes  for the same characteristics  at the same place, or locus.
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4 Gametes only have one set of chromosomes Cells with two sets of chromosomes are said to be diploid . Gametes, eggs and sperm, are haploid , with a single set of chromosomes. Sexual life cycles involve the alternation of haploid and diploid stages.
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5 Mitosis and development Multicellular diploid adults (2 n = 46) Diploid zygote (2 n = 46) 2 n Meiosis Fertilization Egg cell Sperm cell n Haploid gametes ( n = 23) n
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6 Meiosis Meiosis reduces the chromosome number from diploid to haploid. Meiosis, like mitosis, is preceded by chromosome duplication. In meiosis, though, the cell divides twice to form four daughter cells.
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7 The first division, meiosis I Starts with synapsis , the pairing of homologous chromosomes in
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Meiosis and Chromosomes - Download 11 Meiosis and...

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