ExplainAnswer these genetic questions please A purebreeding

Explain/Answer these genetic questions please.

A pure-breeding line of white flowering tulips is crossed with a pure-breeding line of pink tulips. The F1 progeny all have pink flowers, Which trait is dominant? You self the pink F1 progeny and observe a 15:1 ratio of pink:white flowering F2 progeny. Draw a potential biochemical pathway for production of pink pigment, and indicate how the gene(s) responsible for producing pink pigment fit into this pathway.

Solution

(a) Let us denote the genotype of the pure breeding white flowering tulips as WW and the genotype of the pure breeding pink flowering tulips as PP.

The F1 generation cross will give all progeny as: WWPP

It is given that all the F1 generation tulips are pink in color. Therefore, according to Mendel\'s laws of inheritance, the dominant phenotype is physically expressed in Mendelian crosses, when present in homozygous or heterozygous condition.

Therefore n the heterozygous condition of WP, pink (PP) is the dominant trait.

(b) Now that it is known that pink is the dominant trait, let us rename the genotypes as:

Pink: PP

white: pp

So F1 generation offsprings will have genotype: Pp

When F1 offsprings are self-crossed, the offsprings are:

Pp x Pp

F2 offsprings: PP, Pp, Pp, pp

According to Mendel\'s law, the F2 offspring phenotype ratio should have been 3:1. But, the observed ratio is 15:1 (Pink flower: white flower). This anomaly is due to duplication of genes in the case of tetraploid genetics.