Which trait is determined by genetics alone?
1 answer:
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From a Punnett square you can get the genotypic and phenotypic proportions of the progeny produced from a cross. Cross: PpRr x PpRr. F1: PPRR, PPRr, PPRr, PPrr, PpRr, Pprr, ppRR, ppRr, pprr.
<h3>What is a Punnett square?</h3>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.
In the exposed example, we know that two genes are involved in the cross.
As we can see, there are dominant and recessive alleles for both genes.
Since each genotype in the square results from the combination of parental gametes, we can figure out which are the parental genotypes.
For instance, let us consider the provided genotypes
- PPRr.
We can assume one of the parents provided a P and a R dominant alleles, while the other parent provided another P allele but a r recessive allele.
PR + Pr ⇒ PPRr
- ppRr.
One of the parents provided a p recessive allele and a R dominant allele, The other parent provided another p allele and a r recessive allele.
pR + pr ⇒ ppRr
- pprr.
Both parents provided p and r recessive alleles.
pr + pr ⇒ pprr
From this information, we can assume parents are heterozygous for both genes.
Cross:
Parentals) PpRr x PpRr
Gametes) PR, Pr, pR, pr PR, Pr, pR, pr
Punnett square) PR Pr pR pr
PR PPRR PPRr PpRR PpRr
Pr PPRr PPrr PpRr Pprr
pR PpRR PpRr ppRR ppRr
pr PpRr Pprr ppRr pprr
F1) 1/16 individuals are expected to be PPRR
2/16 individuals are epected to be PPRr
1/16 individuals are expected to be PPrr
2/16 individuals are expected to be PpRR
4/16 individuals are expected to be PpRr
2/16 individuals are expected to be Pprr
1/16 individuals are expected to be ppRR
2/16 individuals are expected to be ppRr
1/16 individuals are expected to be pprr
For a better understanding, you will find the Punnett square in the attached files representing the parental gametes with different colors, and the resulting genotypes with a combination of these colors.
In this way, you will notice which gamete comes from which parent.
You can learn more about Punnett squares at
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