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Human Karyotypes
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Karyotypes = pictures of homologous chromosomes lined up during metaphase 1 23 pairs of chromosomes (1 set from the mother & 1 set from the father) - 22 pairs are autosomes - 1 pair is sex chromosomes XX = female ♀ & XY = male ♂
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About Chromosomes Chomosomes = structures of tightly coiled chromatin (DNA) Homologous chromosomes = chromosomes of same size & shape carry the same genes for the same traits
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Chromosomal Theory of Inheritance “Genes are located on chromosomes”
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Genes - are hereditary units of DNA - control characteristics & abnormalities - exist in different forms called alleles
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ALLELES Dominant – shows whenever present - designated w/capital letters T = tall Recessive – shows only if the organism is homozygous - masked w/dominant alleles - designated w/lowercase letters t = short
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GENOTYPE = genetic makeup HOMOZYGOUS (Pure) - organism has 2 identical alleles for a trait TT or tt HETEROZYGOUS (hybrid) - organism has 2 different alleles for a trait Tt
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PHENOTYPE Physical appearance an organism develops as a result of its genotype PhenotypeGenotype Pure tall plant TT (homozygous dominant) Pure short planttt (homozygous recessive) Hybrid tall plantTt (heterozygous)
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Mendel’s Peas
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