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8.7: Chapter 8 Summary

Last updated

Mar 1, 2024
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- 8.6: Factors Causing Deviation from Mendelian Phenotypic Ratios
- 8.8: Key Terms in Chapter 8

Natasha Ramroop Singh
Thompson Rivers University

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The topics covered in this chapter can be summarized as follows:

Phenotypes depends on the alleles that are present, their dominance relationships, and sometimes also interactions with the environment and other factors.
The alleles of different loci are inherited independently of each other, unless they are genetically linked.
Many important traits show continuous, rather than discrete variation. These are called quantitative traits.
Many quantitative traits are influenced by a combination of environment and genetics.
The expected phenotypic ratio of a dihybrid cross is 9:3:3:1, except in cases of linkage or gene interactions that modify this ratio.
Modified ratios from 9:3:3:1 are seen in the case of recessive and dominant epistasis, duplicate genes, and complementary gene action. This usually indicates that the two genes interact within the same biological pathway.
There are other factors that alter the expected Mendelian ratios.

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