Lecture 12-14

The protein:lipid ratio in a typical membrane (e.g. red blood cells) is approximately

1:1

If you had a patient in which the lung epithelium was leaking fluids from the bloodstream into the lumen of the lung, which of the following is the most likely cause?

A mutation in a cell adhesion molecule

Which adaptation specific to becoming multicellular compensates for the destabilizing effect of increased size? (Think carefully about answer choices!)

Both ECM and tight junctions

Consuming very large amounts of certain foods/drinks can affect the digestive system in profound ways. Which of the following would LEAST likely cause some sort of osmotic shock to your stomach and intestinal cells if you consumed a very large amount of it in a short period of time?

Butter

Which of the following most closely approximates a second messenger? Ca+ ions flowing into the cytoplasm and there binding to a protein on the secretory vesicles causing them to fuse with the plasma membrane and secrete their contents. The enzyme cyclic GMP phosphodiesterase, (catalyzes cGMP --> GMP), which is activated when photons interact with the light "receptor" rhodopsin in rod photoreceptors of the eye. An odorant receptor on the surface of a mouse olfactory epithelium cell that undergoes a conformational change upon binding of metabolites (breakdown products) of thyroid hormones, activating an intracellular G-protein. The neurotransmitter secreted by a neuron in response to an electrical impulse traveling down its axon.

Ca+ ions flowing into the cytoplasm and there binding to a protein on the secretory vesicles causing them to fuse with the plasma membrane and secrete their contents.

Shown below are the results of two fluorescence recovery after photobleaching (FRAP) experiments. Which of the following could explain the difference between the data represented by the dashed line as compared to that represented by the solid line?

FRAP was performed on the same cell but at a lower temperature.

Which of the following is least likely to diffuse through a cell's plasma membrane?

H+

Which of the following can be considered both an advantage and a disadvantage of juxtracrine signaling?

It affects only one or a very small number of cells.

Which of the following is a disadvantage of being a multicellular organism specifically as opposed to unicellular? (read and think carefully!)

More difficult to absorb nutrients

Which of the following should be able to diffuse most easily through a cell's plasma membrane?

O2

Cell adhesion molecules are important components of:

tight junctions