Problem Set 2
1. The log P for chloroform (CHCl3) was found to be
1.97 for a mixture of 200 mL of water and 300 mL of 1-octanol.
- Calculate the value of
the partition coefficient P.
- Based upon the value of
P, discuss the underlying reasons ( in terms of intermolecular
forces) for the solubility behavior of chloroform in 1-octanol vs.
water.
- If the water phase had
a chloroform concentration of 0.125 mM,
calculate the expected concentration of
chloroform in the 1-octanol phase.
- Describe how the two
chloroform concentrations would change (increase, decrease, or no change)
if 100 mL of water were added to the mixture.
- For the addition of
this 100 mL of water to the mixture, predict
whether and how the total mass of chloroform present in the octanol phase would change.
- Draw a diagram of a
container holding this mixture and clearly label the concentration of each
of the phases.
- Use thermodynamics to
explain and to predict how the concentration of chloroform in water would
change with an increase in temperature (assume constant volumes of
liquids).
2. Explain how each of the following properties
affects membrane fluidity; clearly explain why for each of these:
- Temperature
- Increase in the chain
length of phospholipid fatty acid components
- Increase in the degree
of unsaturation of phospholipid
fatty acid chains
- Increase in the amount
of cholesterol found in the membrane
3. Draw the structure of a phospholipids molecule
showing all atoms, bonds and charges; clearly label
the subcomponent parts.
4. A recent paper
noted that binding assay results from delta unit binding to ATP synthase revealed a Kd
of 1.4 nM. Write
the equation for and calculate the DG
for dissociation of the [delta unit – ATP synthase]
complex. Does the sign of your answer make sense?