In com, the allele A allows the deposition of anthocyanin...

In com, the allele $A$ allows the deposition of anthocyanin (blue) pigment in the kemels (seeds), while aa plants have yellow kemels. At a second gene, $W_{-}$ produces smooth kemels, while ww kemels are wrinkled. A plant with blue smooth kemels was crossed to a plant with yellow wrinkled kernels. The progeny consisted of 1447 blue smooth, 169 blue wrinkled, 186 yellow smooth, and 1510 yellow wrinkled. a. Are the $a$ and $w$ loci linked? If so, how far apart are they? b. What was the genotype of the blue smooth parent? Include the chromosome arrangement of alleles. c. If a plant grown from a blue wrinkled progeny seed is crossed to a plant grown from a yellow . smooth $F_1$ seed, what kinds of kernels would be expected, and in what proportions?

In com, the allele $A$ allows the deposition of anthocyanin (blue) pigment in the kemels (seeds), while aa plants have yellow kemels. At a second gene, $W_{-}$ produces smooth kemels, while ww kemels are wrinkled. A plant with blue smooth kemels was crossed to a plant with yellow wrinkled kernels. The progeny consisted of 1447 blue smooth, 169 blue wrinkled, 186 yellow smooth, and 1510 yellow wrinkled.
a. Are the $a$ and $w$ loci linked? If so, how far apart are they?
b. What was the genotype of the blue smooth parent? Include the chromosome arrangement of alleles.
c. If a plant grown from a blue wrinkled progeny seed is crossed to a plant grown from a yellow . smooth $F_1$ seed, what kinds of kernels would be expected, and in what proportions?

Key Concepts

Parental and Recombinant Gametes

Parental (non-recombinant) and recombinant gametes refer to the types of gametes produced in a cross between heterozygotes for linked genes. Parental gametes carry the allelic combinations that were present in the parents, while recombinant gametes result from crossing over that shuffles the alleles, leading to new allele combinations that were not found in the original parental configuration.

Chromosomal Arrangement (Phase/Coupling)

Chromosomal arrangement, or phase, is the configuration of alleles on homologous chromosomes, indicating whether dominant or recessive alleles for two genes are situated on the same chromosome (in coupling) or on opposite chromosomes (in repulsion). This arrangement is crucial in predicting the types of gametes produced, especially when dealing with linked genes.

Gene Linkage

Gene linkage refers to the phenomenon where genes that are located close together on the same chromosome tend to be inherited together during meiosis because the physical proximity reduces the likelihood of a crossover event between them. This concept contrasts with independent assortment, which applies to genes on different chromosomes or those far apart on the same chromosome.

Recombination Frequency

Recombination frequency is the proportion of recombinant offspring produced in a cross, and it is used as a measure of the physical distance between linked genes. It is expressed in map units (or centiMorgans), where 1 map unit is equivalent to a 1% chance of recombination occurring between two genes during meiosis.

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