Three genes control the production of tail structures in dogs. The wag1 gene promotes the production of tail structures. However, the brkn gene inhibits wag1 activity. Another gene, ntrdr, stimulates activity of the brkn gene. Put these genes in order in a developmental pathway. Use arrows and t-bars between the genes as appropriate.

You conducted an experiment in which you knocked out the activity of the ntrdr gene in early embryological development. Will tail structures be produced by this animal?

a. Yes

b. No

1. ntrdr - -> brken - -| wag1 - -> Tail structures

2. Yes

Explanation:

(1) In this experiment three different genes are present;

1) Wag-1 - promotes production of tail structures

2) brkn gene - inhibits Wag-1 which leads to inhibition or inactive Wag1 gene and there is no tail formation.

3) ntrdr gene - stimulates the activity of brkn gene thus this in turn inhibits Wag-1 gene and results in inhibiting the tail formation.

(2) The ntrdr gene stimulates the brkn gene and active brkn gene inhibits the wag-1 gene. As we know Wag1 gene is essential for tail formation. on removing out ntrdr gene result in inactive gene brkn thus allows the expression of the Wag-1 gene allowing tail growth in dogs.