BIOL 2905 Lecture 20: Mandel
25 Oct 2017
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Document Summary
Later modification, additions to mendel"s hypotheses: some phenotypes exhibit variations on a complete dominance: recessive relationships. Humans sex chromosomes: sex chromosomes: determines gender. X & y chromosomes in many species. Xy: male: other chromosomes called autosomes, human x chromosomes- large (2350 genes, human y chromosomes- small (fewer genes), contains sry gene. Sry gene becomes active & gives rise to male genes. Xy: short pseudoautosomal (homologous) regions interact during meiosis. They are homologous between x & y chromosomes. Cross leads to exchange in alleles: non-homologous (differential) regions. Human sex-linked genes: sex-linked genes mean that gen is on sex chromosomes (x &y, not necessarily involved in sex determination or direct. Human genetics: autosomal recessive inheritance, heterozygotes are carriers & homozygous recessives are affect by trait, in autosomal dominant inheritance, only homozygous recessive are unaffected. Cystic fibrosis: in autosomal recessive inheritance, heterozygotes are carriers & homozygous recessive are affected by traits. If cells don not have communications this is not possible.
