Question

Many traits, such as the coats of mammals are produced by the interaction of many genes. In this problem, you will demonstrate understanding of genetics of a fictional animal called Tribbles, made famous on Star Trek several years ago. While some Tribbles reproduce asexually, Federation Scientists are exploring a remote planet with a population of Tribbles that produce sexually and demonstrate some interesting patterns and bright colors. You have been called in to help determine the genetic patterns in Tribble crosses and boldly go where no one has gone before.

You make the following observations:

1. A cross between a purebred lime green Tribble and a purebred red Tribble produces offspring that are all red.
2. A cross between a long haired Tribble and a short haired Tribble produces fuzzy, (medium length hair), offspring.
3. Occasionally an unusual plaid coated Tribble is born. The plaid offspring are almost always male, and in most cases, neither parent is plaid. A plaid male rarely has a plaid male son, but the father must be plaid for the female offspring to be plaid.
4. Tribbles with whiskers can have long whiskers, short whiskers, a mix of long and short whiskers or no whiskers at all.

18. From the list above determine which trait represents (you will use one letter more than once) –

______ dominant(expressed)/recessive(not-expressed) pattern,

______ co-dominance(expression) pattern

______ incomplete dominance(expression) pattern

______ multiple alleles

______ sex-linked pattern

Answer 1

a) Purebred red tribble trait represents dominance and Purebred lime green tribble trait shows recessiveness because in   F₁ generation offsprings are all red completely. This shows the dominance of red trait over lime green trait.

b) 2nd observation shows incomplete dominance where long haired tribble and short haired tribble produces fuzzy . Here none of the traits show there complete dominance and thus hybrid has not completely any of above pattern.

c) 3rd one shows sex linked pattern as it can be easily noted that is is linked with sex chromosomes.

d) Last one shows co-dominance pattern and multiple alleles pattern as there could be mix of long and shot whiskers which shows co dominance and could have no whiskers , long whiskers and short whiskers pattern which shows the presence of more than two alleles in trait and that's why multiple allele pattern results are found.