Exam 21: Quantitative Genetics and Multifactorial Traits

We often refer to the host of genetic factors in the genome that have an influence on a particular gene's expression as its genetic background. What influence does genetic background have over the phenotype of the organism?

Typically, one thinks of identical (MZ) twins being genetically identical. However, genomic differences do exist between MZ twins by epigenetic processes. What are epigenetic processes?

Name two mammalian traits with relatively high heritability (h2) values and two with relatively low h2 values.

Individuals with the same genetic background and a high degree of homozygosity are said to be isogenic. Of what value are isogenic strains in genetic studies?

What are QTLs and RFLPs?

Assume that you are studying a trait determined by a number of polygenes. If there are seven phenotypic categories, how many genes are probably involved?

As used in twin studies in mammals, distinguish between the terms concordant and discordant.

In the analysis of quantitative traits, positions on chromosomes called quantitative trait loci (QTLs) are often discussed. In the same context, restriction fragment length polymorphisms (RFLPs) are also discussed. What is the relationship between QTLs and RFLPs?

Interpret the meaning of an H2 (broad -sense heritability) value that approaches 0.0.

What is the term given to a random subset of individuals who are selected for measurement in a particular study?

Heritability is a measure of the degree to which the phenotypic variation of a given trait is due to genetic factors.

Provide a brief description of discontinuous inheritance and continuous inheritance. How are the two related? How are they different?