Unit 2: The Fluid Mosaic Model Flashcards
A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose.
What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane’s permeability to glucose?
Permeability to glucose will increase
In which direction do phospholipids move in the membrane?
laterally (sideways)
Why is the membrane fluid?
Weak bonds between unsaturated phospholipids keep it always moving. These increase in cold temperatures for plants so the membrane doesn’t become solid.
The membrane is composed of a fluid _____ of ______ with embedded amphipathic proteins.
bilayer, phospholipids
What would happen if carbohydrates are missing from the membrane?
the cell-cell recognition function will be affected
This molecule is likely to lack hydrophilic domains
cholesterol
Why are the internal and external layers of the bilayer membrane different?
The two layers of a cell membrane face different environments and carry out different functions.
____ will diffuse through a cell membrane
small hydrophobic molecules
Which of the following molecules would likely diffuse through the lipid bilayer of a plasma membrane most rapidly?
A) sucrose
B) an amino acid
C) O2
D) Na+
C) O2
A defect in ____ would dramatically reduce the rate of diffusion of water across cell membranes
aquaphorin
A new drug designed for the treatment of lung cancer must specifically enter the cytoplasm of lung cells while not entering the cells of other tissues.
Which characteristic would likely enhance the specificity of this drug?
the similarity to molecules normally transported by lung cells
a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
diffusion
Which of the following cellular processes includes all of the others?
A) osmosis
B) facilitated diffusion
C) passive transport
D) transport of an ion down its electrochemical gradient
C) passive transport
When the interior of a cell is in equilibrium with its environment
There is random movement of molecules into and out of the cell.
water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
osmosis
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.
What is the relationship between the solutions on both sides of the U-tube?
side A is isotonic to side B
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.
What happens when the system has reached equilibrium?
The water level will be higher in side A than in side B.
The solutions in the two arms of a U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels on both sides are equal.
When the system reaches equilibrium, the sugar concentrations on both sides will be ____
1.5 M sucrose, 1.5 M glucose
The force driving simple diffusion is ________, while the energy source for active transport is ________.
concentration gradient; ATP hydrolysis
phagocytosis
white blood cells engulf bacteria
What is the cause of the disease familial hypercholesterolemia?
defective LDL receptors on the membrane
