Mendelian Genetics In tomato plants, the gene R has two alleles that control fruit color: the...

Mendelian Genetics

In tomato plants, the gene R has two alleles that control fruit color: the R allele is dominant and produces red tomatoes; the r allele is recessive, and when homozygous produces yellow tomatoes. Gene T controls plant height: the T allele is dominant and produces tall plants; the t allele is recessive and when homozygous produces dwarf plants. Genes R and T undergo independent assortment.

A. Parental tomato plants of genotype RRTT and rrtt are crossed. What genotype and phenotype do you expect in the F₁ generation?

B. The F₁ tomatoes are interbred. Draw a Punnett Square to predict the genotypes and phenotypes that will be seen in the F₂ generation. Why is this only a prediction?
C. What fraction of the F₂ generation is expected to be purebreeding?
D. Would you expect to see the same or different results if the parental tomato plants had genotypes RRtt and rrTT?

Solutions

Expert Solution

AS the parental genotypes RRTT and rrtt are crossed, we get the F1 progeny as RrTt (which means tall plants with red tomatoes) In F1 genration, the alleles for each gene are in heterozygous condition.

the cross will be shown here

As provided in the punnett square, the genotypes as well as phenotypes are clear.

Here we can get two parental combinations (Red, Tall) and (Yellow dwarf) and two recombinants (Red, dwarf) and (Yellow tall).

The results depicted in the table is just a prediction as we believe that the two genes assort independently. and that the formation and fusion of gametes is a random process.

C) out of the siz combinations listed in the above table, genotypically only two combinations are pure breeds (homozygoous for both characters) - RRTT and rrtt

therefore fraction of purebreeding will be 2/16 = 0.125

D) Yes

gladiator answered 2 months ago

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