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Unformatted text preview: Chapter 5 The Inheritance of Single-Gene Differences Overview In matings, precise phenotypic ratios are produced in descendants as a result of chromosome segregation. In heterozygotes, alleles segregate equally into meiotic products. Progeny ratios can be predicted from known genotypes of parents. Parental genotypes can be inferred from phenotypes of progeny. In many organisms, sex chromosomes determine sex. X-linked genes can show different phenotypic ratios in male and female progeny. In humans, single-gene traits can be studied in pedigrees. Organelle genes are inherited maternally. Meiotic chromosome segregation In meiosis, each of the four haploid products receives one of each kind of chromosome A/A homozygotes all get A chromosomes A/a heterozygotes half get A chromosomes half get a chromosomes As a consequence of chromosome segregation, alleles of heterozygotes segregate equally Equal segregation First observed by Mendel in crosses with peas Readily observed using some fungi and protists in which all four haploid products of meiocyte (tetrad)...
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This note was uploaded on 09/21/2009 for the course MCB 5896 taught by Professor Zhang during the Spring '08 term at UConn.
- Spring '08