Chapter 12 (Part 2)
Explain the principle of independent assortment and its relation to meiosis: The segregation of chromosomes in anaphase I of meiosis explains Mendel's observation that each parent gives one allele for each trait at random to each offspring, regardless of whether the allele is expressed. The segregation of chromosomes at random during anaphase I explains Mendel's observation that factors, or genes, for different traits are inherited independently of each other.
Apply the rules of probability to infer genotypes from test crosses A test cross is used to determine the genotype of an individual with a dominant trait. Because the trait is dominant, an individual with the trait could be homozygous or heterozygous for the trait. (This cannot always be determined by simply looking at the phenotype of the individual.) In a test cross, an individual with the dominant phenotype is crossed with a fully recessive individual Define the concepts of polygenic inheritance and pleiotropy
polygenic inheritance is a non-Mendelian form of inheritance in which a particular trait is produced by the interaction of many genes. Polygenic inheritance refers to the kind of inheritance in which the trait is produced from the cumulative effects of many genes in contrast to monogenic inheritancewherein the trait results from the expression of one gene (or one gene pair). In humans, height, weight, and skin color are examples of polygenic inheritance, which does not follow a Mendelian pattern of inheritance. pleiotropy is the single gene controlling or influencing multiple (and possibly unrelated) phenotypic traits. Mutation in this type of gene will simultaneously affect more than one trait. An example is phenylketonuria, a human disease caused by mutation(s) in a single gene that codes for the enzyme, phenylalanine hydroxylase. The disease is characterized by mental retardation and reduced hair and skin pigmentation.
List and explain other factors that...
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