Independent Assortment
Independent Assortment
& Probability
Soliving a Punnett Square Review
***Put steps in order***
1.
2.
3.
Create a cheat sheet for reading your
punnett square
figure out genotypic & Phenotypic ratios
genotypic = #AA:#Aa:#aa
phenotypic = #dominant trait:#recessive trait
Determine Parental (P) genotypes
homozygous dominant = AA
heterozygous = Aa
homozygous recessive = aa
4.
Fill in PUnnett Square
What is independent assortment?
· alleles are distributed randomly during gamete
formation
genes on separate chromosomes sort independently
during meiosis I
DiHybrid Crosses
· crossing 2 traits at a time
· independent assortment allows us to determine
the possibility of inheriting 2 different traits at the
same time
ex. GgYy x GgYy
Dihybrid Example
Green peas (G) are dominant over yellow
***ONLY
peas (g). Tall plants (T) are dominant over INTERESTED
IN
short plants (t). If I cross a heterozygous
PARENTAL
GENOTYPES AND
green, heterozygous tall plant with a
PHENOTYPIC
heterozygous green, heterozygous tall
RATIOS***
plant, what will the offspring look like?
Parental Genotypes:
Can we get...offspring?
green, tall
green, short
yellow, tall
yellow short
Determining Gametes - F.O.I.L.
Parental Genotypes: GgTt x GgTt
GgTt
GgTt
First -
First -
Outside -
Outside -
Inside -
Inside -
Last -
Last -
Independent Assortment
Filling in Punnett Square
Gt
GT
gT
Short CUT
***REDUCE gametes at the beginning***
gt
# of offspring...
green, tall -
GT
GgTt x ggtt
FOIL to find gametes
green, short -
Gt
# of offspring...
green, tall -
yellow, tall yellow short -
green, short -
gT
yellow, tall -
gt
yellow short -
Phenotypic Ratio:
Phenotypic Ratio:
AaBb x AaBb will always have a
phenotypic ratio of 9:3:3:1
Memorize
Short CUT
Short CUT
***REDUCE gametes at the beginning***
***REDUCE gametes at the beginning***
GgTt x GGTt
FOIL to find gametes
ggTt x GGtt
FOIL to find gametes
# of offspring...
green, tall -
# of offspring...
green, tall -
green, short -
green, short -
yellow, tall -
yellow, tall -
yellow short -
yellow short -
Phenotypic Ratio:
Phenotypic Ratio:
Probability Practice
Probability
· wants to know what is mathematically possible
ex. What is the probability of getting tails 4 times in a row?
Predict the probability of Aabbdd.
ex. If the both parents have genotypes AaBb, what is
the probability of getting an offspring that is...
A a
AaBB
aaBB
aabb
Predict the probability of AABBDD.
Predict the probability of AaBbDd.
· helps to determine genotypic ratios in multiple
trait crosses
AaBb
1. Parent are AABbDd x AaBBDd.
2. Parents are AaBbDdEe x AaBbDdEe.
A
Predict the probability of AABBDDEE.
a
Predict the probability of AaBBDdEE.
B b
B
b
Predict the probability of aabbddee.