In some plants, a red pigment is made from a colorless precursor. The addition o

Question

In some plants, a red pigment is made from a colorless precursor. The addition of a hydroxyl group (OH) to the red pigment causes it to become purple. In a cross between 2 randomly selected purple plants; the following progeny is obtained: 94 purple; 31 red; 43 white.

a. What mode of inheritance is involved in determining flower color?

b. Based on your answer above, assign a genotype to each of the above phenotypes.

c. Propose a metabolic (biochemical) pathway for the production of this purple pigment.

Explanation / Answer

Answer:

a) incomplete dominance

b) The ratio, 94: 31: 43 is nearly same as 9:3:4

9 purple : 3 red : 4 colorless.

R: red
r: colorless
H: hydroxyl group
h: no hydroxyl

R-H- purple
R-hh red
rrH- colorless
rrhh colorless

c) Anthocyanins are water-soluble vacuolar pigmentsthat may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway

Anthocyanin pigments are assembled like all other flavonoids from two different streams of chemical raw materials in the cell:

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