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This chapter explain the chromosomal theory of inheritance and its discovery, explain why sex-linked diseases are more common in human males than females, distinguish between sex-linked genes and linked genes, explain how meiosis accounts for recombinant phenotypes, explain how linkage maps are constructed,. | Lecture Biology (7th edition) - Chapter 15: The chromosomal basis of inheritance Chapter 15 The Chromosomal Basis of Inheritance PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Overview: Locating Genes on Chromosomes • Genes – Are located on chromosomes – Can be visualized using certain techniques Figure 15.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept 15.1: Mendelian inheritance has its physical basis in the behavior of chromosomes • Several researchers proposed in the early 1900s that genes are located on chromosomes • The behavior of chromosomes during meiosis was said to account for Mendel’s laws of segregation and independent assortment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The chromosome theory of inheritance states that – Mendelian genes have specific loci on chromosomes – Chromosomes undergo segregation and independent assortment Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The chromosomal basis of Mendel’s laws P Generation Yellow-round Starting with two true-breeding pea plants, Green-wrinkled we follow two genes through the F1 and F2 seeds (YYRR) seeds (yyrr) Y y generations. The two genes specify seed r color (allele Y for yellow and allele y for Y R R r green) and seed shape (allele R for round y and allele r for wrinkled). These two genes are on different chromosomes. (Peas have seven Meiosis chromosome pairs, but only two pairs are illustrated here.) Fertilization R Y y r Gametes All F1 plants produce yellow-round seeds (YyRr) R R F1 Generation y y r r Y Y Meiosis LAW OF SEGREGATION LAW OF INDEPENDENT ASSORTMENT R r r R Two equally probable Y y arrangements Y y of chromosomes 1 Alleles at both loci segregate at