Question

Illustrate a cell that is 2n = 4, after DNA replication before mitosis. The cell is heterozygous for the B gene, and homozygous recessive for the F gene. If there is more than one possibility, draw all.

Answer 1

In picture I, the two genes are on separate pair of homologous chromosomes. For B gene, one of the homologous chromosomes contains the dominant allele and another chromosome contains recessive allele. For f gene, both of the homologous chromosomes contain the recessive allele.

In picture II, the two genes are on same pair of homologous chromosomes, let's say homologous chromosomes pair 1. One hromosome of the homologous chromosome pair contains dominant B allele, recessive f allele and the other contains recessive b allele, recessive f allele.

In picture III, the two genes are on same pair of another set of homologous chromosomes, let's say homologous chromosomes pair 2. One chromosome of the homologous chromosome pair contains dominant B allele, recessive f allele and another contains recessive b allele, recessive f allele.

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