GENETICS 21 Introductory Genetics TUTORIAL 1-Mendelian Genetics 1. Two short-eared pigs were mated each year for 3 matings. ofthe progeny over the three 7 no ears, 18 had short ears and 5 had long e Explain these results. Help: A diagram of the cross may help you, then how many genes and alleles do you think may be involved in determining ear size in pigs? Propose genotypes for each of he phenotypes and consider the relationship between alleles and genes if you think more than one gene is involved. 2. There are several mutant eye colours seen in Drosophila, one of which is purple. Homozygous wild red-eyed flies are pr pr and flies with purple eyes are prpr. Another mutation affects the length of the wings: vestigial (vg) gives the wings a ‘scrunched up look. Homozygous normal-winged flies (wild type) are vg vg and vestigial-winged flies are VEvg. The wild type alleles (pr and vg are dominant and both genes are autosomal. a. Early last century, Morgan and his co-workers carried out many experiments with Drosophila. From one of these experiments involving the testcrossing of pr pr vg vg females to prpr vgvg males the following progeny were scored. Gametes from the female T Observed Offspring Phenotype Wild type (red eyes, normal wings) Red eyes, vestigial wing 965 1,067 Purple eyes, normal wing 146 Purple eyes, vestigial wing pr vg 2,335 i. What do these data tell us about the two genes ii. Identify the recombinant phenotypes in the progeny. iii. Estimate the map distance between the two genes. b. What are the genotypes of the homozygous parents of the Fifemales used in the testcross? Are the alleles in the Fi females in coupling phase or repulsion phase?