Download Problem set : Chemical signals in Animals

Problem Set : Chemical signals in Animals.
1. Define :
1. Autocrine :
2. Paracrine :
3. Endocrine:
4. Hormone :
2 a.Testosterone is a male sex hormone (androgen), which controls development
of male sex organs and many other male secondary sex characteristics. The
average blood testosterone level in men in their thirties is 700ng/dl. How many
nanograms of testosterone would a healthy 70kg, 35 year old man have on
average in his body? Amount of blood (in litres) in the body is 8% of body weight
(in Kg).
b. In young men, infections such as mumps or viral infections, removal of the
testes due to cancer or trauma, and certain genetic abnormalities may cause
Testosterone Insufficiency i.e testosterone serum level below 350 ng/dl. By how
much (in nanograms) does the testosterone level in the person mentioned in 2a
have to decrease for him to have the condition mentioned in 2b?
3. Sexual selection arises from differences in mating success between
individuals in a population. Male birds defend territories and sing during the
breeding season to attract mates. Increases in testosterone levels result in
increases in aggression and singing.
a. Baseline testosterone levels in male birds are around 0.1ng/mL. If 2 ng/mL of
testosterone in the blood causes 8 singing events per hour, and the most
successful males are singing 40 times per hour, what is the concentration of
testosterone in the blood of these most successful males?
10 ng/mL
b. Assume a female bird requires at least 24 singing events per hour to illicit a
mating response. You capture a male and find out he has a testosterone
concentration of 5.3 ng/mL. How often is this male singing and is he likely to
attract a female?
21 times per hour. No
c. While continuous increases in testosterone seem to be favored by sexual
selection, elevated testosterone levels inhibit the immune system, and can cause
susceptibility to disease. If testosterone levels of 10.7 ng/mL are enough to lead
to a disease, what is the maximum number of singing events per hour a male can
achieve before becoming susceptible to disease?
42 singing events per hour would be the highest.
4. Anabolic-androgenic steroids (AAS), are a class of steroid hormones related to
the hormone testosterone. They increase protein synthesis within cells, which
results in the buildup of cellular tissue (anabolism), especially in muscles.
Synthetic AAS is widely (and sadly!) misused by sportsmen across the world as a
performance enhancement drug in-spite of being banned by the sports governing
bodies for various ethical and medical reasons.
a. List a few medical issues that you think could arise from the use of synthetic
anabolic–androgenic steroids.
b. Methandrostenolone (Dianabol, Danabol, DBOL) is an anabolic steroid
originally developed by John Ziegler and released in the US in the early 1960's
by Ciba. DBOL binds to the androgen receptor in our cells and initiates the
expression of genes, protein synthesis ultimately resulting in yielding muscle
strength in a short space of time. If you were to test the effects of this drug in a
mouse whose androgen receptor gene is mutated and hence inactive, what
would be your expected results? Why?
c. Russian research, based on rat studies, concluded that the most effective
dose of DBOL was 0.5mg per kilo of bodyweight. If so, how many moles of
DBOL should be consumed by an athlete who weighs 70kgs to extract maximum
benefit? The chemical formula of DBOL is C20H28O2 . Atomic mass of carbon,
hydrogen and oxygen are 14 amu, 1 amu and 16 amu respectively.
d. If an athlete consumes 30mg of DBOL, how many molecules of DBOL is he
ingesting? If the half-life of DBOL is 6 hours, how many molecules of DBOL
would be present in his blood 24 hours after ingestion? If 1X10 19 molecules of
DBOL in blood is the cut-off to test positive in a drug test conducted by WADA
(World Anti-Doping Agency), will this athlete test positive 24 hours post-DBOL
consumption?
5. Take home question: Find three sports figures who were tested positive for
performance enhancing drugs. Research and find the drug they used, its
mechanism of action and the associated side-effects. Knowing their harmful
effects would you recommend or condemn their use? Write down your findings in
less than 500 words and submit it to your TA.