Download NOTES Dihybrid PPT

A. Introduction
1. Method Used:
Punnett Square
2. Principle:
Complete Dominance
3. Data:
Black fur is dominant to white fur. Curly fur is
dominant to straight fur.
Gene pairs:
( B-b ) ( C-c )
“B” stands for black
“C” stands for curly
“b” stands for white
‘c’ stands for straight
4. List all the possible genotypes using B, b, C, c
[from most to least dominant ]
WE ARE GOING TO USE THE FOIL METHOD!!!!!!
First…Outside…Inside…Last
Gametes possible (”N”):
BC
Bc
bC
Eggs
BC
Bc
bC
bc
bc
1.
2.
3.
4.
5.
6.
7.
8.
9.
BBCC
BBCc
BbCC
BbCc
BBcc
Bbcc
bbCC
bbCc
bbcc
Sperm
DESCRIBE EACH OF THESE INDIVIDUAL’S PHENOTYPE
A. Complete a Parent cross
1.) P cross
2.)
3.) BBCC x bbcc
4.) black,curly white, straight
BC
bc
bc
BbCc
BbCc
bc
BbCc
bc
BbCc
BC
BC
BC
BbCc
BbCc
BbCc
BbCc
BbCc
BbCc
BbCc
BbCc
BbCc
6. Genotypes
BbCc : ------16 : 0
BbCc
BbCc
BbCc
7. Phenotypes
Black,Curly:------16 : 0
B. F1 Cross
[cross between two individuals who are hybrid for two genes/traits]
(heterozygous black, heterozygous curly X heterozygous black, heterozygous curly)
[ BbCc ] x [ BbCc ]
1.) F1 cross
2.)
3.) BbCc x BbCc
4.) Black, Curly Black, Curly
BC
BC
BBCC
Bc
bC
bc
BBCc
BbCC
BbCc
BBcc
BbCc
Bbcc
bbCC
bbCc
Bc
BBCc
bC
BbCC
BbCc
bc
BbCc
Bbcc
bbCc
bbcc
Calculate the genotype and phenotype ratios by counting:
Genotype Ratio
1
2
2
4
1
2
1
2
1
1. BBCC
2. BBCc
3. BbCC
4. BbCc
5. BBcc
6. Bbcc
7. bbCC
8. bbCc
9. bbcc
1:2:2:4:1:2:1:2:1
Phenotype Ratio
9
1. Black & Curly
3
2. Black & Straight
3
3. White & Curly
1
4. White & Straight
9:3:3:1