Genetics 2313 Exam Chapter 17, 18, 5-7 Review Complete

Chapter 17: Quantitative Genetics Chapter 18: Population Genetics Chapter 5: Linkage and Chromosome Mapping Chapter 6: Chromosome Variation Chapter 7: Bacterial and Viral Genetic System Chapter 17: Quantitative Genetics 17.1 Quantitative genetics is the analysis of complex characteristics or characteristics influenced by multiple gene factors - Discontinuous (or qualitative) characteristics are phenotypes that fall into two or more distinct non-overlapping classes or varieties ● Ex: Eye color or blood groups - Continuous (or quantitative) characteristics are phenotypic distributions that vary from one extreme to another in an overlapping fashion, often expressed in a bell-shaped curve ● Ex: Height, weight or heart rate Quantitative characteristics can be influenced by: - Polygenic inheritance ● Occurs when the characteristics can be encoded by many genes at many loci, thus creating a combination of different traits - Environmental factors ● Ex: Temperature or chemical exposure If a characteristic is polygenic and can be influenced by environmental factors, it is said to be multifactorial For qualitative characteristics, one genotype may produce one phenotype OR many genotypes may produce one identical phenotype (due to epistasis and dominance) However, for quantitative characteristics, the number of possible characteristics increases in accordance with the number of mutant genes Question #1: If there are 2 alleles (one pair of genes) at each locus and 4 loci are present, how many possible genotypes are there? How many total phenotypes do they produce? - Answer: 81 possible genotypes and 9 total phenotypes are produced ● To calculate the possible number of genotypes, use the equation