This document discusses different types of genes and inheritance patterns: 1) Lethal genes can be dominant or recessive, with recessive lethal alleles following a 2:1 genotypic to phenotypic ratio as seen in mouse coat color. 2) Linked genes on the same chromosome are inherited together and do not follow Mendel's laws of independent assortment unless separated by crossing over. This is demonstrated using examples in fruit flies. 3) Sex is determined by X and Y chromosomes in humans, with females as XX and males as XY. Sex-linked genes on the X chromosome are inherited differently between males and females.

4. If we cross two heterozygotes, expect a 3:1 ratio in progeny But, in yellow x yellow cross, get: 2 yellow : 1 nonyellow Explanation:

7. Coat color of rodents P : Yellow X Yellow Yy Yy G : Y y Y y F1: YY Yy yY yy Yellow Yellow Yellow Grey (Die)

9. Inheritance of Huntington’s allele

11. Linked genes in Drosophila

19. X c X c Color blind X X C Y Normal X C X c X C X c X c Y X c Y Parent gamete progeny 100% carrier 100% color blind X c X c X C Y

21. Transmission of sex-linked genes