Testosterone is a hormone produced in the male testes. During a boy's pubescent years (ages 9 to 14), there is an increase in production that leads to male secondary sexual characteristics such as a deeper voice, more muscle mass, facial hair growth and enlargement of the Adam's apple (among others). Some teenage boys experience these puberty changes at later ages than others. The timing of puberty is often genetically determined (through heredity), but other factors can play a role in delaying it, such as poor nutrition, physical trauma and certain diseases. Stimulating testosterone production naturally is possible in teen boys, although in rare cases hormone therapy may be needed to trigger and complete puberty.
Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?
A) in or near the active site
B) at an allosteric site
C) at a cofactor binding site
D) in regions of the protein that determine packaging into the virus capsid
E) such mutations could occur anywhere with equal probability