Question

Please help with this genetic question. If possible, show work. Thank you !

Question 29 0/2 pts Two unlinked, epistatic genes regulate production of flower pigments in diploid sweet peas, as shown in the metabolic pathway below. Each gene codes for the production of an enzyme, and each gene has two possible alleles-dominant and recessive. Plants with at least one dominant R allele will produce the blue pigment. Plants with at least one dominant R allele and at least one dominant Sallele will produce the purple pigment. Plants with no dominate Rallele will produce no pigment (white), regardless of the Sgene. Gene R (enzyme 1) Gene S (enzyme 2) white precursor - > blue-colored pigment - purple-colored pigment A homozygous plant that is blue-flowered is crossed with a homozygous plant that is white-flowered to produce all purple- flowered F1 plants. If two of the F1 are crossed, what phenotypic ratio is expected in the F2? You Answered • 1 purple: O blue: 0 white 9 purple: 4 blue: 3 white Correct Answer 9 purple: 3 blue : 4 white 1 purple: 2 blue: 1 white None of the above is correct.

Answer 1

RRSS ( blue ) * rrss ( white )

F1 progeny result in formation of RrSs ( purple color)

selfing of F1 generation :

F2 generation

RrSs *RrSs

	RS	Rs	rS	rs
RS	RRSS	RRSs	RrSS	RrSs
Rs	RRSs	RRss	RrSs	Rrss
rS	RrSS	RrSs	rrSS	rrSs
rs	RrSs	Rrss	rrSs	rrss

recessive epistatsis : where one gene mask the effect of other gene

9- R_S_ ( purple )

4- rrss , rrS_ ( white )

3- R _ss ( blue )