can someone explain how to solve this problem. An inbred strain of plants has a

Question

can someone explain how to solve this problem.

An inbred strain of plants has a meani height 48 cm. A second strain of the same species from a different geographic region also has a mean height 48 cm, When plants from the twe the F are crossed together, the F, plants are the same height as the parent plants. However 1000 are shows a wide range of the majority is Ike the Pand Fiplants, but 6 in only 24 cm high and 6 in I000 are 72 om high, a) How many genes are involved? b) How much cm does each contributory add to plant height? types for the original Pparents and the F Plants that could c) Indicate one possible set of g account for these (F2) results. Pape l 1 Genetics Problem Set Polygenic and Linkagel

Explanation / Answer

Answer:

a. We see that the two extreme heights (24 cm and 72 cm) are in the same ratio (both 6/1000) which tells us that the gene for height is additively inherited. So, its a poygenic inheritance.

The ratios of the two extremes is 6/1000 or 3/500.

n = number of genes involved

500/3 = 22n or 166.66 = 22n

Applying log, log 166.66 = 2n log 2

2.22 = 2n*0.3

2n = 7.4

so, n = 3.7, almost 4

n = 4 genes

b. First we shall figure out the number of phenotypes: 2n+1= 2(4) + 1 = 9 phenotypes

There are 8 increments between each phenotype. The range of phenotypes is between 24 cm and 72 cm.

72 - 24 = 48

So, 48 / 8 = 6 cm

Each additive allele contributes to 6 cm in height

c. In order to get the spectrum of phenotypes that range from 24 cm to 72 cm in the F2 generation, we know that the F1 generation must be AaBbCcDdx AaBbCcDd

P1 can be any of the following:

: AABBccdd x aabbCCDD

: AAbbCCdd x aaBBccDD

: aaBBCCdd x AAbbccDD

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