Inheritance Pattern Complexity complexity from how genes transmitted Sex linkage Linkage (coming soon!) complexity from how genes function dominance relationships multiple alleles pleiotropy conditional gene expression penetrance & expressivity [Intragenic interactions] Intergenic Gene interactions (epistasis)
epistasis 1. Genetics. An interaction between nonallelic genes, especially an interaction in which one gene suppresses the expression of another. American Heritage Dictionary of the English Language 2. Medicine. A film that forms over the surface of a urine specimen. 3. The suppression of a bodily discharge or secretion.
Epistasis can be described as either recessive epistasis or dominant epistasis. recessive epistasis example: color in Labrador Retrievers DOMINANT epistasis example: squash fruit color
2 genes: Recessive Epistasis: Labrador Retrievers B controls color E controls B B- black bb chocolate only if E- ee golden regardless of B ee is epistatic to any B genotype
You have decided to breed your golden retriever (bbee) with the neighbor s chocolate retriever (bbee). What color pups will you and your neighbor have to fight over? A. & D. only B. & E. only C. & bb Ee ee chocolate golden
2 genes: Recessive Epistasis: Labrador Retrievers B controls color E controls B B- black bb chocolate only if E- ee golden regardless of B Bb;Ee x Bb;Ee F 2 phenotypic ratio?
B controls color E controls B B- black bb chocolate only if E- ee golden regardless of B 9 B_E_ : 3 B_ ee : 3 bbe_ : 1 eebb phenotype? phenotype? phenotype? phenotype? black golden chocolate golden 9 black : 4 (= 3 + 1) golden : 3 chocolate
Dominant Epistasis: Squash fruit color 2 genes: ww yy ww Y- green yellow W- Y- white W- yy white W is epistatic to any Y genotype
Dominant Epistasis: Squash fruit color 2 genes: ww yy ww Y- green yellow W- Y- white W- yy white Ww;Yy x Ww;Yy F 2 phenotypic ratio?
2 genes: Dominant Epistasis: Squash fruit color ww yy ww Y- green yellow W- Y- white W- yy white 9 W_ Y_ : 3 W_ yy : 3 ww Y_ : 1 ww yy 12 (= 9 + 3) white : 3 yellow : 1 green
Coat color in mice cc is epistatic to B gene BB black Bb black bb agouti Bb x Bb 3 black : 1 agouti P: CC bb x cc BB (agouti) (white) F 1 : Cc Bb (black) F 2 : 9/16 black C_ B_ 3/16 agouti C_ bb 4/16 white cc (3+1) CC pigmented Cc pigmented cc albino Cc x Cc 3 pigmented : 1 albino
Coat color in mice P: CC bb x cc BB (agouti) (white) cc is epistatic to B gene BB black Bb black bb agouti Bb x Bb F 1 : Cc Bb (black) F 2 : 9/16 black C_ B_ 3/16 agouti C_ bb 4/16 white cc (3+1) 3 black C : 1 agouti B precursor pigment 1 pigment 2 (white) (agouti) (black) Cc x Cc CC pigmented Cc pigmented cc albino B C pigment 1 3 pigmented pigment : 1 albino 2 deposited in hair (agouti) (black)
(duplicate recessive epistasis) figure 13.19 complementary gene action C P white precursor purple pigment 9/16 C_ P_ 3/16 C_ pp 3/16 cc P_ 1/16 cc pp
(duplicate recessive epistasis) figure 13.19 complementary gene action cc C P white precursor X purple pigment 9/16 C_ P_ 3/16 C_ pp 3/16 cc P_ 1/16 cc pp
(duplicate recessive epistasis) figure 13.19 complementary gene action C P pp white precursor X purple pigment 9/16 C_ P_ 3/16 C_ pp 3/16 cc P_ 1/16 cc pp
A_B_ A_bb aab_ aabb 9 3 3 1 12:3:1 10:3:3 9:6:1 9:4:3 15:1 13:3 12:4 10:6 9:7
substance O G 4 enzyme 4 substance P G 3 substance M enzyme 3 substance N In this pathway, the conversion of precursor substance M to substance N is catalyzed by enzyme 3, which is encoded by gene, G 3. The conversion of precursor substance O to substance P is catalyzed by enzyme 4, which is encoded by gene, G 4. Substance P negatively regulates the synthesis of substance N by binding enzyme 3, thereby inactivating it.
complementary gene action
strain 11a w1/w1 w1a/w w1 /w1 strain 22 w2/w2 w2b/w b w1 /w1 strain w3/w3 w3/w33 w2/w2 strain w4/w4 wa4/w3 /w44 a w3 strain 5 5 b w5/w5 w5b/w w3 /w3 6 6 c strain w3 w6/w6 w6c/w /w3 7 7 d strain w3 w7/w7 w7d/w /w3 8 8 a strain w4 w8/w8 w8a/w /w4 9 9 b strain w4 w9/w9 w9b/w /w4 c strain w4 w10/w10 w10c/w4 /w1010
Complementation is the phenomenon in which two recessive mutations with similar/identical phenotypes result in a wild-type phenotype when both are heterozygous in the same genotype. Complementation means that the mutations are in different genes. Complementation distinguishes different genes based on functional criteria.
2 mutant alleles of 1 gene? OR mutations in 2 different genes???
2 mutant alleles of 1 gene? OR mutations in 2 different genes?