Respuesta :
The Punnett square is used to get the probabilities of getting offspring with different genotypes and phenotype. There were 0% chances that Timmy's mother could express a different genotype.
What is a Punnett square?
The Punnett square is a graphic representation that shows the different types of gamete combinations according to the alleles involved in a cross.
Punnett square shows the probabilities of getting offspring with different genotypes and their consequent phenotypes.
Let us analyze Timmy's family.
Remember we are talking about a somatic diallelic gene taht expresses complete dominance,
- F is the dominant allele and codes for freckles
- f is the recessive allele and does not code for freckles.
Family's genotypes
- Timmy ⇒ FF
- Sally ⇒ Ff
- Mother ⇒ Ff
- Father ⇒ Ff
- Maternal grandfather ⇒ FF
- Materal grandmother ⇒ ff
Timmy's mother and father are heterozygous for this trait, meaning the genotypic ratios of their progeny is 1:2:1 (25% FF + 50% Ff + 25% ff).
Parents' cross: Ff x Ff
Punnett square) F f
F FF Ff
f Ff ff
F1)
25% of their progeny was expected to be homozygous dominant, FF, expressing freckles.
50% was expected to be heterozygous Ff expressing freckles.
25% was expected to be homozygous recessibe, ff, with no freckles.
The genotypic ratio of Timmy and Sally progeny will be 1:1 (50% FF + 50% Ff).
Timmy and Sally' cross: FF x Ff
Punnett square) F F
F FF FF
f Ff Ff
F1)
50% of their progeny are expected to be homozygous dominant, FF, expressing freckles.
50% are expected to be heterozygous Ff expressing freckles.
Grandparents' cross: FF x ff
Punnett square) F F
f Ff Ff
f Ff Ff
F1) Their whole progeny was expected to be heterozygous Ff expressing freckles.
There were 0% chances that Timmy's mother could express a different genotype.
You will learn more about Punnett squares at
https://brainly.com/question/25357981
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Complete question
Trait F is the Mendelian trait for freckles, where F is dominant over f.
- Timmy is homozygous dominant for trait F.
- Timmy mates with Sally who is heterozygous for trait F.
- Timmy’s father and Timmy’s mother are both heterozygous for trait F.
- Timmy’s maternal grandmother (mother’s mother) is homozygous recessive for trait F.
- Timmy’s maternal grandfather (mother’s father) is homozygous dominant for trait F.
Looking at the Punnett square for his grandparent's mating, what was the probability of Timmy's mother having a different genotype?
