Question

A Better Way? As you can see, Punnett squares for phenotypes that involve several genes can get complicated. If you can recognize the patterns, you can make a mathematical model to figure out how common or rare a particular genotype or phenotype would be, depending on the number of genes involved. To do this, you begin by figuring out how many different combinations of alleles each Fparent could contribute to the F2 generation. When one gene-A-was involved, each parent could contribute one of two alleles: A or AM. When two genes-A and B-were involved, each parent could contribute any of four allele combinations: ABAMBA BM or AMBM. When three genes are involved, each parent could contribute any one of eight allele combinations, and so on. • Next, determine the proportion of the F2 offspring that you'd expect to inherit alleles only from teosinte. You have already determined this figure based on your crosses. • When one gene is involved, of the F2 offspring were expected to look just like teosinte because they inherited only teosinte alleles. Note that 4 is 41 • When two genes are involved, 1/16 of the F2 offspring were expected to look just like teosinte because they inherited only teosinte alleles. Note that 16 is 42 • When three genes are involved, 1/64 of the F2 offspring were expected to look just like teosinte because they inherited only teosinte alleles. Note that 64 is 43. Do you notice the pattern? What proportion of F2 offspring would you expect to look just like teosinte if four genes controlled the differences between maize and teosinte? NOTE: Calculate out the number for the answer.

Answer 1

• 1/256.
• Because as four genes are involved upperlimit  is 4^4 .
• as when one gene is involved 1/4 of the F2 offspring look like tenosinte lower limit is also 4.
• 4^4 = 256