Genetics

Chapter 14 #5 A black guinea pig crossed with an albino guinea pig produces 12 black offspring. When the albino is crossed with a second black one, 7 blacks and 5 albinos are obtained. What is the best explanation for this genetic situation? Write genotypes for the parents, gametes, and offspring Answer Albino (b) is a recessive trait; black (B) is dominant. First cross: parents BB ? bb; gametes B and b; offspring all Bb (black coat). Second cross: parents bb ? Bb; gametes 1/2 B and 1/2 b (heterozygous parent) and b; offspring 1/2 Bb and 1/2 bb #6

Chapter 15 The Chromosomal Basis of Inheritance Overview: Locating Genes Along Chromosomes Mendel?s ?hereditary factors? were genes, though this wasn?t known at the time Today we can show that genes are located on chromosomes The location of a particular gene can be seen by tagging isolated chromosomes with a fluorescent dye that highlights the gene Concept 15.1: Mendelian inheritance has its physical basis in the behavior of chromosomes Mitosis and meiosis were first described in the late 1800s The chromosome theory of inheritance states: Mendelian genes have specific loci (positions) on chromosomes Chromosomes undergo segregation and independent assortment The behavior of chromosomes during meiosis was said to account for Mendel?s laws of segregation and independent assortment