Campbell Biology : Concepts and Connections

Jane B. Reece, Martha R. Taylor, Eric J. Simon

ISBN #9780321885326

8th Edition

608 Questions

40,754 Students Helped

Homework Questions

Summary

Learning Objectives

Key Concepts

Example Problems

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Summary

This section explores the fundamental principles of Mendelian genetics, covering the laws of segregation and independent assortment, and extends into the complexities arising from incomplete dominance, codominance, pleiotropy, and polygenic inheritance. It explains how chromosome behavior underpins these laws, including gene linkage and the effects of crossing over, and discusses the unique inheritance patterns of sex-linked traits. Understanding these concepts is essential for predicting phenotypic ratios, mapping genes, and applying genetic principles to real-world situations such as disease screening and tracing human evolution through the Y chromosome.

Learning Objectives

Key Concepts

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Example Problems

Example 1

Complete this concept map to help you review some key concepts of genetics. (EQUATION CAN'T COPY)

Example 2

Whether an allele is dominant or recessive depends on a. how common the allele is, relative to other alleles. b. whether it is inherited from the mother or the father. c. whether it or another allele determines the phenotype when both are present. whetber or pot it is linked to other

Example 3

Edward was found to be heterozygous ( $S s$ ) for sickle-cell trait. The alleles represented by the letters $S$ and $s$ are a. linked. b. on homologous chromosomes. c. both present in each of Edward's sperm cells. d. on the same chromosome but far apart.

Example 4

Two fruit flies with eyes of the usual red color are crossed, and their offspring are as follows: 77 red-eyed males, 71 ruby-eyed males, 152 red-eyed females. The allele for ruby eyes is a. autosomal (carried on an autosome) and dominant. b. autosomal and recessive. c. sex-linked and dominant. d. sex-linked and recessive.

Example 5

A man with type B blood and a woman who has type A blood could have children of which of the following phenotypes? a. A or B only b. AB only c. AB or $\mathrm{O}$ d. $A, B, A B,$ or $O$