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G e n e t i c s N e w s. Summary for Exam II - Do it NOW!. Office hours underutilization. Problem Set 7 available. Problem Set 8 available. Exam I …. not available. Our answers and comments on web. Click on Course at a Glance; then Click on Exams; Answer Keys. Topics for Today. - PowerPoint PPT PresentationTRANSCRIPT
Genetics News
• Problem Set 7 available
• Summary for Exam II- Do it NOW!
• Problem Set 8 available
• Exam I … not available
• Office hours underutilization
Our answers and comments on web. Click on Course at a Glance; then Click on Exams; Answer Keys
Topics for Today
• Sex linkage/Sex limitation
•Calculation of probabilities from pedigree
• Extension of Mendelian Genetics - Multiple alleles determining one trait - Multiple genes determining one trait - Multiple genes with additive effect
Study Question 6
How is the trait inherited?
Autosomal dominant
Dd
Dd Dd x
Study Question 6
How is the trait inherited?
Autosomal dominant
Autosomal recessivedd
Dd Dd
xdd
Dd Dd
dd
Dd Dd
Study Question 6
How is the trait inherited?
Autosomal dominant
Autosomal recessive
Sex-linked dominant
XDY
XDY XXD
x
Study Question 6
How is the trait inherited?
Autosomal dominant
Autosomal recessive
Sex-linked dominant
Sex-linked recessive
XdY
XXd
XdY
XXdXY
XdY
XXd XY
Study Question 6Could it be an autosomal dominant trait limited to
males?
Dd
Dd Dd
Dd
dd Dd
Dd
ddDdYes
Study Question 8What is the probability that IV.1 will get the disease?
P(III.2 x III.3 XdY)Specify:
Parse: P(III.2 is XXd)
AND P(III.2 passes Xd)XdY ?
AND P(III.3 is XY)
AND P(III.3 passes Y)
XXd ? XY
1/2
1/2
1
?Solve:
XXd
1/2
Probability = 1/8
Multiple Genes/One Trait
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Substrate1 Product1 Substrate2 Product2 A B
Conventional dihybrid cross
Multiple Genes/One Trait
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Substrate1 Substrate2 Product A B
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Dihybrid cross of interacting genes
9 : 3 : 3 : 1 = 9 : 7
Multiple Genes/One Trait
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
chorismate compound X tryptophan M N
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Dihybrid cross of interacting genes
9 : 3 : 3 : 1 = 9 : 7
Study Question 17
You cross a vermilion-eyed fly with a cinnibar-eyed fly to obtain F1 progeny, then you cross these progeny to get F2 progeny. What phenotypic ratio do you expect?
Study Question 17
CV Cv cV cv
CV CCVV CCVv CcVV CcVv
Cv CCVv CCvv CcVv Ccvv
cV CcVV CcVv ccVV ccVv
cv CcVv Ccvv ccVv ccvv
Substrate1 Substrate2 Product V C
Dihybrid cross of interacting genes CV Cv cV cv
CV CCVV CCVv CcVV CcVv
Cv CCVv CCvv CcVv Ccvv
cV CcVV CcVv ccVV ccVv
cv CcVv Ccvv ccVv ccvv
Study Question 17
Substrate1 Substrate2 Product V C
Dihybrid cross of interacting genes CV Cv cV cv
CV CCVV CCVv CcVV CcVv
Cv CCVv CCvv CcVv Ccvv
cV CcVV CcVv ccVV ccVv
cv CcVv Ccvv ccVv ccvv
9 : ? : ? : ?
Study Question 17
Substrate1 Substrate2 Product V C
Dihybrid cross of interacting genes CV Cv cV cv
CV CCVV CCVv CcVV CcVv
Cv CCVv CCvv CcVv Ccvv
cV CcVV CcVv ccVV ccVv
cv CcVv Ccvv ccVv ccvv
9 : 3 : ? : 1
Multiple Genes/One Trait
Substrate1 Substrate2 Product V C
Dihybrid cross of interacting genes
9 : 3 : 3 : 1 = 9 : 3 : 4
CV Cv cV cv
CV CCVV CCVv CcVV CcVv
Cv CCVv CCvv CcVv Ccvv
cV CcVV CcVv ccVV ccVv
cv CcVv Ccvv ccVv ccvv
9 : 3 : 3 : 1
Study Question 19
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Substrate1 Product1 Substrate2 Product2 A B
Conventional dihybrid cross
Pathway where dihybrid
cross gives 15:1 ratio?
Study Question 19
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Substrate1 Product1 Substrate2 Product2 A B
What kind of genetic situation can you imagine that would lead to a 15:1 phenotypic ratio?
9 : 3 : 3 : 1 9 : 3 : 3 : 1 15 : 1
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
Study Question 20
You find corn with kernels in the ratio:
Yellow 247Golden 154Sickly green 23
Hypothesis?
Hypothesis: One gene, multiple alleles
AB x CD 1:(1:1):1= 1:2:1
Study Question 20One gene hypothesis
You find corn with kernels in the ratio:
Yellow 247Golden 154Sickly green 23
TOTAL 424
A B
C AC BC
D AD BD
Exp Obs
Unit
= 424/4 = 106
212106106424
Study Question 20Two gene hypothesis
You find corn with kernels in the ratio:
Yellow 247Golden 154Sickly green 23
Hypothesis?
Hypothesis: Two genes for one trait
AaBb x AaBb 9:3:3:1
Study Question 20Two gene hypothesis
You find corn with kernels in the ratio:
Yellow 247Golden 154Sickly green 23
TOTAL 424
Exp Obs
Unit
= 424/16
= 26.5
AB Ab aB ab
AB AABB AABb AaBB AaBb
Ab AABb AAbb AaBb Aabb
aB AaBB AaBb aaBB aaBb
ab AaBb Aabb aaBb aabb
238.5 = 26.5 x 9159 = 26.5 x 6 26.5 = 26.5 x 1424