1. LECTURE 11: FROM GENE TO PHENOTYPE II Fchapter 6 Fquestions & concepts Fgenes & gene products Fallele interactions Fgene & protein interactions Fchi-square applications Fexam 1: problems

2. GENE & PROTEIN INTERACTIONS Fhow do you identify interacting genes? 1. generate new mutant alleles for a trait of interest by mutagenesis 2. test mutant alleles to determine if they represent alleles of multiple genes by (a) mapping & (b) complementation 3. combine mutant alleles to identify epistatic interactions

3. GENE & PROTEIN INTERACTIONS Fa complementation test will reveal allelic relationships 1 gene (below)... 1. dominance / recessiveness 2. semi-dominance = incomplete dominance 3. co-dominance ( e.g. : I A & I B of ABO system) 4. multiple alleles ( e.g. : I A, I B & i of ABO system) 5. conditional ( e.g. : temperature sensitive) 6. lethality 7. sterility F... or give wild type phenotypes 2 genes

4. Fare mutations allelic (1 gene) or not (2 genes)? Ftest by making pair-wise crosses between mutants COMPLEMENTATION TEST

6.  gene  genes COMPLEMENTATION TEST

7. F... because the 2 mutations are in different genes

8. Fwhat is epistasis? text (1): a situation in which the differential phenotypic expression of a genotype at one locus depends on the genotype at another locus text (2): a mutation that exerts its expression while canceling the expression of the alleles of another gene Herr Doktor Professor: interactive expression of alleles at two (or more) genes (both of the text definitions are limiting) GENE & PROTEIN INTERACTIONS

9. Mendelian phenotypic ratios

10. FMendelian dihybrid ratio GENE & PROTEIN INTERACTIONS

11.   Mendelian dihybrid ratio parallel pathways dominant epistasis recessive epistasis duplicate additive genes duplicate dominant genes duplicate recessive genes recessive suppression (1) recessive suppression (2)

12. PARALLEL PATHWAYS bw + /_; st + /_ 9 bw + /_; st/st 3 bw/bw; st + /_ 3 bw/bw; st/st 1 9 : 3 : 3 : 1

13. PARALLEL PATHWAYS o + /_; b + /_ 9 o + /_; b/b 3 o/o; b + /_ 3 o/o; b/b 1 9 : 3 : 3 : 1

14. DOMINANT EPISTASIS D/_; W/_ 9 d/d; W/_ 3 D/_; w/w 3 d/d; w/w 1 12 : 3 : 1 W  D gene expression

15. RECESSIVE EPISTASIS w + /_; m + /_ 9 w + /_; m/m 3 w/w; m + /_ 3 w/w; m/m 1 9 : 3 : 4

16. DUPLICATE DOMINANT GENES A 1 /_; A 2 /_ 9 A 1 /_; a 2 /a 2 3 a 1 /a 1 ; A 2 /_ 3 a 1 /a 1 ; a 2 /a 2 1 15 : 1 1 dominant allele  pigment

17. DUPLICATE RECESSIVE GENES (aka COMPLEMENTARY GENE ACTION) C/_; P/_ 9 C/_; p/p 3 c/c; P/_ 3 c/c; p/p 1 9 : 7 1 recessive allele  pigment

18. REGULATING GENE & TARGET INTERACTION r + /_; a + /_ 9 r/r; a + /_ 3 r + /_; a/a 3 r/r; a/a 1 9 : 7

19. (A POSSIBLE) SUPPRESSION MECHANISM

20. RECESSIVE SUPPRESSION pd + /_; su + /_ 9 pd + /_; su/su 3 pd/pd; su + /_ 3 pd/pd; su/su 1 13 : 3 pd + su + pd supd mechanism for genotype  not explained by model

21. GENE & PROTEIN INTERACTIONS   Mendelian dihybrid ratio parallel pathways dominant epistasis recessive epistasis duplicate additive genes duplicate dominant genes duplicate recessive genes recessive suppression (1) recessive suppression (2)

22. MODIFIERS Fmodifier mutations influence expression of a mutation at a second locus Fbroadly used term (text gives a few examples) Fgene activity can be modified by... Fup- or down-regulation Fenhancement or suppression

23. SYNTHETIC LETHALS

24. PENETRANCE & EXPRESSIVITY Fpenetrance: the % of individuals of given genotype that exhibit a phenotype... a population measurement Fexpressivity: the extent to which a given genotype is expressed at the phenotypic level... in each individual

25. PENETRANCE & EXPRESSIVITY Fcan be due to... 1. environmental factors 2. genetic factors 3. unknown / difficult to measure (text) ??? F e.g., the rover / sitter foraging polymorphism

26. POLYGENY GENE  GENE  PHENOTYPE GENE      BIOCHEMICAL PATHWAY:       PHENOTYPE   COMPETITION / INHIBITION:   PHENOTYPE     ENZYME CATALYSIS:     PHENOTYPE

27. PLEIOTROPY PHENOTYPE  GENE PHENOTYPE  PHENOTYPE    SEQUENTIAL PHENOTYPES:GENE         RELATED PHENOTYPES:GENE       UNRELATED PHENOTYPES:GENE    

28. GENE & PROTEIN INTERACTIONS        

29. CHI-SQUARE APPLICATIONS Fexample question on p. 209 Ftrue-breeding P yellow x red petal plants all orange petal F 1. F 1 are bred & F 2 are... red 77 orange182 yellow 61 total320 Fwith 3 phenotypes, reasonable hypotheses are... H 1 = incomplete dominance... 1:2:1 ratio E = 80 G 1 /G 1 + 160 G 1 /G 2 + 80 G 2 /G 2  2 = 7.6, P < 0.025 (2.5%),  H 1 

30. H 2 = recessive epistasis of r on Y & y... 9:3:4 ratio E = 180 Y/_; R/_ + 60 y/y; R/_ + 80 [ Y/_; r/r + y/y; r/r ]  2 = 0.15, P > 0.9 (90%),  H 2  CHI-SQUARE APPLICATIONS Fexample question on p. 209 Ftrue-breeding P yellow x red petal plants all orange petal F 1. F 1 are bred & F 2 are... red 77 orange182 yellow 61 total320 Fwith 3 phenotypes, reasonable hypotheses are...

31. PRACTICE PROBLEMS you should be able to do CH6, p. 214 # 1 - 50