Bio ch 6

What physical property is often associated with these chemical differences?

C=C bonds normally result in kinks that increase the spacing between fats and thus make unsaturated fats more fluid than saturated fats.

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?

CO2

In an experiment involving planar bilayers, a solution of table salt (sodium and chloride ions in water) is added on the left side of the membrane while pure water is added on the right side. After 30 minutes, the researchers test for the presence of ions on each side of the membrane. The right side tests negative for ions. What can you conclude?

In an experiment involving planar bilayers, a solution of table salt (sodium and chloride ions in water) is added on the left side of the membrane while pure water is added on the right side. After 30 minutes, the researchers test for the presence of ions on each side of the membrane. The right side tests negative for ions. What can you conclude? Ions cannot cross planar bilayers.

Which of the following is true of osmosis? -Osmosis is an energy-demanding or "active" process. -Osmosis only takes place in red blood cells. -In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. -In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.

In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

How do fats differ from proteins, nucleic acids and polysaccharides?

Only fats do not form from the polymerization of monomers

How is the chemical structure of saturated fats different from that of unsaturated fats?

Saturated fats have fatty acid tails with only C−C bonds while unsaturated fats have one or more C=C bonds in the tails.

Steroids are considered to be lipids because they

are not soluble in water

Molecules that are amphipathic must contain

both hydrophilic and hydrophobic regions

Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water

is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

Lipids that form membranes have what kind of structure?

polar heads and nonpolar tails; the polar heads interact with water

Lipids are insoluble in water because

they contain nonpolar C-C and C-H bonds