Obesity Research: You will be assigned to one of these three areas of obesity
research. After researching your topic, different groups will be picked to teach the
whole class what they have found.
Group 1: Leptin
Basic Science
a. What is leptin?
b. What does leptin normally do?
c. What is the phenotype of “knockout” mice that lack leptin?
d. What is the phenotype of mice that lack leptin receptors?
e. What happens when you give leptin supplements to mice lacking leptin?
f. What happens when you give leptin to mice lacking the leptin receptor?
Applied Research
g. What happens when you give obese humans leptin?
h. What humans can benefit most from leptin supplements?
i. Are leptin supplements a wonder drug?
Group 2: Peptide YY (PYY)
Basic Science
a. What is PYY?
b. What does it normally do?
c. What is the phenotype of “knockout” mice that lack PYY?
d. What happens when you give mice that lack PYY a supplement of PYY?
e. What happens when you give normal mice a PYYsupplement?
f. The PYY gene has been knocked out by three different researchers. What is the
controversy about their phenotypes?
Applied Science
g. What does this article suggest is the reason that eating a high protein and not a high fat
diet keeps an individual satisfied longer?
h. What happens when PYY is injected into humans?
i. Might PYY be a new anti-obesity wonder drug?
Group 3: Ghrelin and Surgery
Sometimes science works in reverse. For example, gastric bypass surgery works for
obese patients because their appetite decreases. Studies now suggest the physiological
reason for this. What is it?
The ghrelin hormone normally binds a receptor that provides what signal to the brain?
If a pharmaceutical could be developed, what effect would it have to have on ghrelin?
Would it increase or block it? Think of two different ways to design this drug (i.e. what
would it bind to?) Draw these:
What would you predict would be the phenotype of mice that have the ghrelin receptor
gene deleted from their genome?
What has been the problem with previous anti-obesity drugs that made it to market, such
as fen-phen?
Whole class conclusions
There are many genes involved in the obesity trait. Obesity is a __________ trait. How is
obesity defined?
If we wanted to “design” an obese person, what would we want to do to each of these
hormone levels? (Raise or lower?)
PYYLeptin Ghrelin If we wanted to “design” a skinny person, what would we want to do to each of these
hormone levels? (Raise or lower?)
PYYLeptin Ghrelin Does basic science always translate into practical applications? If not, is it a waste?
Aside from a few select obese people in the world with severe genetic mutations, what is
the best “medicine” for most people to keep a healthy weight?