Gene Linkage

For each of the three cells what is the chance of producing a haploid gamete with the genotype AB AXXa BXXb AXXa XX AXXa XX B b B b

Gene Linkage and Mapping If the genes are closer to one another, what happens to their recombination grequency? If Gene A recombines 12% of the time with gene B, but 16% of the time with gene C, which gene is closer to gene A? If gene B and C recombine with one another 28% of the time, what is the order of genes A, B C along the chromosome? Answer the Interactive Question 15.4 on p. 113 in the study guide and then answer the genetics questions on p. 116.

Sex Linkage Why is crossing-over not as common with sex chromosomes? What types of genes are on the sex chromosomes? If there is a gene on the top portion of the X chromosomes and the males have an X and a Y, how many alleles do the have for that one locus? Because of the lack of homology in the sex chromosomes, male only have one allele for some traits. What do we call a male genotype for these genes since he is neither homozygous or heterozygous?

Pedigree Practice Make a pedigree for the following family: 3 generations, some members have the recessive trait of color blindness Genotypes are written as XBXB – for female with normal vision, XBXb for a female who is normal but is a carrier for colorblind, and XbXb for a female who is colorblind; XBY for a male with normal vision and XbY for a male who is colorblind. There are two sets of grandparents in the 1st generation The 2nd generation has at least 8 people half are male and half are female 2 people are married to each other in the 2nd generation. The 3rd generation has at least 6 people, half are male and half are female. The sex-linked trait of male color blindness is present through a heterozygous genotype (XBXb) in the grandmother of one side of the family and in the grandfather (XbY) of the other side of the family. All phenotypes and genotypes should be depicted for all family members.