Lecture 2 Section 2

1. Lecture 2 Section 2 Exceptions to Mendelian Genetics • Today • Administrative issues • Mopping up concepts and terminology • Problems solving • Comments about Key Term set 3 reading assignment

3. If only 70% of individuals with a dominant mutant allele show the dominant trait, the trait is said to be ____. • 70% epistatic • 70% expressive • 70% penetrant • 70% dominant 10 Countdown

5. Gene Gene Product Cell Morphology/Physiology How does genotype affect phenotype? Many genes and the environment act together to determine cellular/… phenotype Tissue Morphology/Physiology Organ Morphology/Physiology Organismal Morphology/Physiology/Behavior Community, population, …

6. A pure-breeding purple plant is crossed to a pure-breeding colorless plant and all the F1 are all purple. An F1 plant is allowed to self-fertilize and produces 160 F2 with the following distribution: 100 purple, 45 blue and 15 colorless. Are these results consistent with model 3? Support your answer by performing a chi-square analysis.

7. What is the expected distribution of progeny phenotypes if you crossed AaCcBB x AaCcBB? C colorless • 9 purple; 4 blue; 3 colorless. • 9 blue; 4 purple; 3 colorless • 9 purple; 4 colorless; 3 blue • 12 blue, 4 colorless 10 Countdown

8. A pure-breeding purple plant is crossed to a pure-breeding colorless plant and all the F1 are all purple. An F1 plant is allowed to self-fertilize and produces 160 F2 with the following distribution: 100 purple, 45 blue and 15 colorless. Are these results consistent with the model? Support your answer by performing a chi-square analysis.

10. Pure-breeding brown-eyed flies (bw- bw- ) are crossed to pure-breeding scarlet-eyed flies (st- st- ). All the F1 have wild type eyes. The F1 are allowed to interbreed to produce an F2. What is the expected distribution of fly eye color in the F2?

11. You have two new recessive mutant lines of flies: both are pure-breeding and both have brighter than wild-type eyes. The genes responsible for the mutant phenotypes are unknown. You know that eye color is controlled by many genes and that different alleles of one gene can lead to different eye colors. You cross the two mutant lines and all the progeny have wild type eyes. This tells you ______.

12. You have two new recessive mutant lines of flies: both are pure-breeding and both have brighter than wild-type eyes. The genes responsible for the mutant phenotypes are unknown. You cross the two mutant lines and all the progeny have wild type eyes. This tells you ______. • That the two lines carry mutations in the same gene. • That the two lines carry different alleles of white gene. • That the two lines carry mutations in different genes. • That the two lines carry different alleles of the scarlet gene. 10 Countdown

13. You have two new recessive mutant lines of flies: both are pure-breeding and both have brighter than wild-type eyes. The genes responsible for the mutant phenotypes are unknown. You know that eye color is controlled by many genes and that different alleles of one gene can lead to different eye colors. You cross the two mutant lines and all the progeny have wild type eyes. This tells you that the mutations are in different genes.Genetic Complementation; Complementation analysis.

14. You cross one bright-eyed mutant female line to males from two different fly lines. Line 1 is pure-breeding for loss of white function (w-Y). Line 2 is pure-breeding for loss of scarlet function (st-st-). The cross to line 1 gives all wild type progeny. The cross to line 2 gives all bright-eyed mutant progeny. This tells you that ____

15. You cross one bright-eyed mutant female line to males from two different fly lines. Line 1 is pure-breeding for loss of white function (w-Y). Line 2 is pure-breeding for loss of scarlet function (st-st-). The cross to line 1 gives all wild type progeny. The cross to line 2 gives all bright-eyed mutant progeny. This tells you that ____ • That the mutant line mutation is recessive to w-. • That the the mutant line carries a birght eye allele of the white gene. • That the mutant line carries a mutation in a gene other than white or scarlet. • That the mutant line carries a mutant allele of the scarlet gene. 10 Countdown

16. Pure-breeding brown-eyed flies (bw- bw- ) are crossed to pure-breeding scarlet-eyed flies (st- st- ). All the F1 have wild type eyes. The F1 are allowed to interbreed to produce an F2. What is the expected distribution of fly eye color in the F2?

17. A white-eyed female is crossed to a wild type male and all the progeny are wild type. If you allow the F1 to interbreed, how many eye-color phenotypes do you expect among the F2?

20. For each pedigree, consider whether or not it COULD BE consistent with X-linked recessive inheritance. Indicate why or why not. Assume 100% penetrance but nothing else.