You are studying a diploid flower you discovered in your back yard. You have map

Question

You are studying a diploid flower you discovered in your back yard. You have mapped two genes, one for flower color (B) and one for leaf shape (A). During your mapping, you learned that these two genes are on different chromosomes. This plant has a phenotype of arrow leaves and blue flowers. A friend recently isolated a new variant of the same plant in Yellowstone park that has round leaves and white flowers, but did not provide any information about the B and A genes in this plant. Both your plant and your friend's plant are homozygous and completely fertile when selfed.

You cross your plant and your friend's plant to obtain the F1 generation which all have arrow leaves and white flowers. The F1 plants were then backcrossed to a tester plant with wild type chromosomal structure and recessive a and b alleles. You find that you have fewer F2 plants than you had expected from this cross in the following phenotypic groups:

Which of the following scenarios best explains your results

You are studying a diploid flower you discovered in your back yard. You have mapped two genes, one for flower color (B) and one for leaf shape (A). During your mapping, you learned that these two genes are on different chromosomes. This plant has a phenotype of arrow leaves and blue flowers. A friend recently isolated a new variant of the same plant in Yellowstone park that has round leaves and white flowers, but did not provide any information about the B and A genes in this plant. Both your plant and your friend's plant are homozygous and completely fertile when selfed.

You cross your plant and your friend's plant to obtain the F1 generation which all have arrow leaves and white flowers. The F1 plants were then backcrossed to a tester plant with wild type chromosomal structure and recessive a and b alleles. You find that you have fewer F2 plants than you had expected from this cross in the following phenotypic groups:

Frequency (# of progeny)    Phenotype Genotype 40 Arrow leaves and White flowers Aa; Bb 10 Arrow leaves and Blue flowers Aa; bb 10 Round leaves and White flowers aa; Bb 40 Round leaves and Blue flowers aa; bb

Which of the following scenarios best explains your results

An inversion between the A and B genes occurred in the plant you found in your back yard. A translocation occurred in the plant your friend found that caused the A and B genes to be linked 40 m.u. apart. No other chromosomal abnormalities are present. A translocation occurred in the plant your friend found that caused the A and B genes to be linked 20 m.u. apart. No other chromosomal abnormalities are present. A translocation occurred in the plant that you found that caused the A and B genes to be linked 10 m.u. apart. No other chromosomal abnormalities are present. A translocation occurred in the plant that you found that caused the A and B genes to be linked 20 m.u. apart. No other chromosomal abnormalities are present. An inversion spanning the entire distance between the A and B genes occurred in the plant your friend found. A transversion involving both genes occurred in the F1

Explanation / Answer

E. A translocation occurred in the plant that you found that caused the A and B genes to be linked 20 m.u. apart. No other chromosomal abnormalities are present.

Explanation:

Recombination frequency = (no. of recombinants / Total progeny) * 100

Hint: Recombinant progeny are always very less in number than the non-recombinants if the genes are linked.

RF = (20/100)100 = 20%

RF(%) = Distance between the gene (mu).

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