Question

Chimpanzee Bonobo -Gorilla Human nontaster allele Human taster allele

these trees can show how similar or different species are from each other. the vertical line on the left is the start and how far to the right each sequence is from the left line or a branch point indicates increasing dissimilarity. so if your sequence is close to the the left line it is similar, but if it is at the end of a long arm on a branch and falls to the right it is less similar.

a) looking at the polygenetic tree, what do you observe about the differences between the species? which species is closest to humans? which is least similar?

b)would you conclude that the other primates are tasters or non-tasters? why is this important? what role might other differences between the species play in an evolutionary sense? think of the role environment might play as well.

Answer 1

a) The species are different as they have evolved differently and hvaing different interanl nodes. Although they have common ancestor from which all the species have evolved but they are diverged later on down the evolution period.

Species closest to humans are human taster allele as humans have ability to taste . The PAV (taster) allele is the ancestral state in humans because these same three amino acids (proline, alanine, and valine) occur at the same positions in the PTC gene product from chimpanzee, lowland gorilla, orangutan, an old world monkey (crab-eating macaque), and a new world monkey (black-handed spider monkey).

b) Humans and non-human primates share the ability to taste, or not taste, a bitter synthetic compound called PTC. Mammalian bitter taste receptors (T2Rs) are encoded by a gene family consisting of a few dozen members. Humans have 25 intact full-length bitter taste receptor-like genes and 10 pseudogenes. T2R pseudogenic accumulation and number of synonymous substitutions per lineage in primates. The proportions of T2R pseudogenes and probably the total number of genes do not differ radically between apes and humans.