1.) a) In the pearl millet plant, color is determined by three alleles at a sing

Question

1.)

a) In the pearl millet plant, color is determined by three alleles at a single locus: Rp1 (red), Rp2 (purple), and rp (green). Red is dominant over purple and green, and purple is dominant over green (Rp1>Rp2>rp). Give the expected phenotypes and ratios of offspring produced by the following crosses SHOW YOUR WORK:

- Rp1/Rp2 x Rp1/rp

- Rp1/rp x Rp2/rp

- Rp1/Rp2 x Rp1/Rp2

- Rp2/rp x rp/rp

- rp/rp x Rp1/ Rp2

b) The LM and LN alleles at the MN blood group locus exhibit codominance. Give the expected genotypes and phenotypes and their ratios in progeny resulting from the following crosses SHOW YOUR WORK:

- LMLM x LMLN

- LNLN x LNLN

- LMLN x LMLN

- LMLN x LNLN

- LMLM x LNLN

Explanation / Answer

Answers:

1. (a) (i) Rp1/Rp2 × Rp1/rp

We expect ¼ Rp1/Rp1 (red), ¼ Rp1/rp (red), ¼ Rp2/Rp1 (red), ¼ Rp2/rp (purple), for overall phenotypic ratio of ¾ red, ¼ purple

(ii) Rp1/rp × Rp2/rp

¼ Rp1/Rp2 (red), ¼ Rp1/rp (red), ¼ Rp2/rp (purple), ¼ rp/rp (green), for overall phenotypic ratio of ½ red, ¼ purple, ¼ green.

(iii) Rp1/Rp2 × Rp1/Rp2

This cross is equivalent to a two-allele cross of heterozygotes, so the expected phenotypic ratio is ¾ red, ¼ purple

(iv) Rp2/rp × rp/rp

Another two-allele cross of a heterozygote with a homozygous recessive. Phenotypic ratio is ½ purple, ½ green.

(v) rp/rp × Rp1/Rp2

½ Rp1/rp (red), ½ Rp2/rp (purple)

(b) Based upon a simple punnet square:

(i) LMLM × LMLN

½ LMLM (type M), ½ LMLN (type MN)

(ii) LNLN × LNLN

All LNLN (type N)

(iii) LMLN × LMLN

½ LMLN (type MN), ¼ LMLM (type M), ¼ LNLN (type N)

(iv) LMLN × LNLN

½ LMLN (type MN), ½ LNLN (type N)

(v) LMLM × LNLN

All LMLN (type MN)

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