Download Biol2250 – Principles of Genetics – Dr Carr Problem solving

Biol2250 – Principles of Genetics – Dr Carr Problem solving Mendelian Genetics 1. A woman is heterozygous for an X-­‐linked recessive allele that causes night-­‐blindness. If she marries a man with normal vision, what proportions of their male and female offspring will inherit the night-­‐blindness? 2. President Grover Cleveland was once accused of fathering a woman’s child. Cleveland was blood type O, the mother was blood type AB, and the child was blood type O. What do the results of the test tell you about Cleveland’s paternity of the child? 3. At the Noddy locus, the hangashore allele (H) is recessive to good-­‐for-­‐nothing (G) and dominant to sleeveen (S). Uncle Sol (a hangashore) marries Mary Mack (a good-­‐for-­‐nothing), and their first child is a sleeveen. What are the genotypes of Sol, Mary, and the child? 4. Of the children of a GS x HS marriage, what proportion will be good-­‐for-­‐nothing? 5. 5. In cats, coat colour is determined by an X-­‐linked locus with two co-­‐dominant alleles: “O” for orange and “B” for black. OB cats are bi-­‐colored (“calico”). I have two cats: Jennet is an orange female; Puszek is a black male. Can Jennet be Puszek’s mother? Can Jennet and Puszek be sister and brother? 6. In cloudberries, loci A & B are autosomally linked. Two AaBb heterozygotes are crossed, one with dominant alleles in trans the other with dominant alleles in cis. If there are no cross-­‐overs between the two loci, what is the expected genotype ratio? 7. Two puffins each heterozygous for two semi-­‐dominant alleles at each of four unlinked loci are crossed. How many F2 phenotypes are expected? 8. When pitcher plants (2n=10) are crossed with catcher plants (2n=14), a small number of low-­‐fertility F1 hybrids are formed. After several generations, a fertile allopolyploid species is formed. How many chromosomes are found the F1 hybrid and the allopolyploid plants? 9. The karyotype of Great Auks comprised a pair of sex chromosomes (one metacentric and one acrocentric), one pair of metacentric autosomes, and two pairs of telocentric autosomes. How many chromosome arms were present in females? How many chromosomes were present in male gametes? 10. Two swiles, one MMQQ and one mmqq, are crossed. When their F1 offspring are crossed, the phenotype of the M-­‐qq F2 offspring is identical to the mmqq parent. What does this indicate about the dominance and epistasis relationships of the M and Q loci?