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IAN PAGE 89 ALLELES. Objective: Identify some of the basic components of Heredity using notes, collaboration and worksheets. MAIN IDEAS Somatic Cells Gametes Homologous Karyotype Alleles. I. Cells contain Pairs of Chromosomes A. WHY PAIRS? (2 Parents!)
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IAN PAGE 89ALLELES Objective: Identify some of the basic components of Heredity using notes, collaboration and worksheets MAIN IDEAS • Somatic Cells • Gametes • Homologous • Karyotype • Alleles
I. Cells contain Pairs of Chromosomes A. WHY PAIRS? (2 Parents!) 1. Sexually reproducing organisms receive 1 set from a female and 1 set from a male.
B. Human Somatic cells contain 46 chromosomes in 23 pairs! 1. Somatic Cell = All the cells in the body except for Gametes =Sex cells.
C. Homologous Chromosome Pairs – contain the same NUMBER & TYPES of genes or ALLELES • Karyotype – matching homologous chromosomes by size & number.
2. Alleles- various forms of the SAME GENE found on homologous chromosomes that may or may not be the same. Ex; Widows Peak or No Widows Peak -Homologous Chromosome # 12 has the gene for Widows Peak!
Dad Mom Widow's Peak Alleles = WW or Ww No Widow's Peak Alleles = ww -One allele codes for Widows peak while the other codes for No Widows Peak.
E. Species have specified number of Chromosomes. (Ex. Humans = 46, Chimpanzees = 48, Fruit flies = 8) 1. Chromosomes are referred to by their number. 2. Human 23rd Pair = Sex Chromosomes a. Known as the X & Y Chromosomes b. Females have XX c. Males have XY