清华大学遗传本科材料.doc

清华大学遗传学部分 Final rehearsal problem set. Genetics-Spring 2003 The real final is about 3 times long, and is formatted in a slightly different way for scoring convenience. 1. (5 pts) Drosophila is used to investigate genes involving the resistance of DTT (a kind of pesticide*). One DTT resistance strain is obtained after multiple rounds of selection. By crossing DTT resistance strain with sensitive strain, DTT resistance of 16 kinds of female progenies is evaluated and shown above. Based on the results, what conclusion can you draw for these DTT resistance genes? *insect killing agent 2. (3pts) A fetus dies in uterus. Several of its cells are karyotyped. About 75% of the cells are dipoid, and 25% tetraploid (have 4 copies of each chromosome). What do you think happened? When in development did it probably occur? 3. (2pts) In yeast, a haploid petite mutant also carries a mutant gene that requires the amino acid histidine for growth. The petite/ his - strain is crossed to a wild-type strain and to yield the following tetrad after sporulation: 2 cells: petite/his - 2 cells: petite/his+ Explain the inheritance of the petite and his - mutations. 4. (2pts) Radiation can generate what kind of DNA damage 1) deletion 2) point mutation 3) translocation 4) ALL OF THE ABOVE 5. (4pts) In an isolated population, an early autosomal-recessive-lethal disease happens 1 in a million. If the allele frequency is stabilized, what mutation frequency for this disease would you expect to arise in each generation? 1/million chromosomes 2/million chromosomes 1/1000 chromosomes 2/1000 chromosomes None of the above 6. (4pts) Here are the DNA fingerprints of five people: a child, mother, and three potential fathers: Mother Offspring Male #1 Male #2 Male #3 Which male(s) could be the father? （孙路 提供） 清