A Few Review Questions…
Question 1
Say that your cells have met all of their ATP needs. If
you eat glucose in excess of your cells’ ATP needs,
what is/are the fates of this glucose, in order of
priority?
Answer: Question 1
If your cells have met all of their energy needs, the
glucose will not go through ATP production
(glycolysis -> citric acid cycle -> ETC). Instead…
The first thing that will happen is glycogen formation -storage of this energy supply in liver and muscle
cells. But the glycogen tanks are also limited in size.
When the glycogen “tanks” get full, the excess glucose
gets synthesized into fatty acids. The first step of this
pathway involves glycolysis, but only to form acetylCoA, involved in fatty acid formation.
Question 2
Protein monomers and lipid monomers are both
absorbed into the bloodstream from the small
intestine. The method by which each molecule type
travels through the blood to the cells is different,
however. Explain why this is, and how the above
molecule types are transported through the
bloodstream.
Answer: Question 2
Amino acids are zwitterionic at neutral pH and therefore
water soluble -- once they are absorbed across the
small intestine lining, they can be transported through
the water-based blood.
However, lipids are nonpolar. They have to be attached
to a protein, forming a lipoprotein (specifically in the
digestive system, a special lipoprotein called a
chylomicron is formed) which is then polar enough to
be transported through the bloodstream.
Question 3
Explain what is involved in designing primers for PCR.
(or, as it’s often referred to, “PCRing up a gene”)
Answer: Question 3


Decide what the boundaries/ends will be of the region
you wish to amplify.
Each primer will be a short nucleotide sequence
(typically 12-15 NT -- you don’t need to know this)
that will bind to your template DNA.
– The 5’->3’ orientation of each primer should be such that
new nucleotides get added moving in toward the center of
your gene after the two strands have been separated.

In a real-life situation, you’d consider re-annealing
temperature (which is dependent on %AT vs. %GC)
as well…
Question 4
You just ate a big, yummy dinner. Describe what is
happening to your blood glucose levels and
hormones released by the pancreas.
(YES, we are assuming that you are not diabetic, and
we are assuming that your meal was reasonably
balanced in terms of carbs/proteins/fats!)
Answer: Question 4
Big meal… blood glucose levels are high.
If you are normal (well… metabolically so), your
pancreas is releasing insulin. This will allow the
glucose to enter your cells for processing in whatever
capacity it decides is proper for the cell’s current
metabolic and energy needs.
Question 5
Some of the proteolytic (protein-digesting) enzymes are
produced by glands found in the lining of the
stomach. However, they are produced as zymogens
and not active until they make contact with HCl inside
the cavity of the stomach. Why do you think this form
of regulation is used by these particular proteolytic
enzymes?
Answer: Question 5
The walls of the stomach contain structural proteins. If
the enzymes were produced from their glands
already in an active form, they would digest the
stomach lining.
Since they are produced in an inactive form, they will
not digest the stomach lining upon release, and they
will not start “doing their business” until they make
contact with HCl, which cleaves off the inactive part
of the zymogen.