Biology Test 2 - Ch.5 Flashcards
The fluid mosaic model of the membrane describes the membrane as..
made of proteins and lipids that can freely move
What chemical property characterizes the interior of the phospholipid bilayer?
It is a hydrophobic.
The transmembrane domain of an integral membrane protein..
-is composed of hydrophobic amino acids
-often forms an a-helical structure
-can cross the membrane multiple times
The specific function of a membrane within a cell is determined by the..
type and number of membrane proteins
The movement of water across a membrane is dependent on..
membrane potential
Cells immersed in a solution of salt and sugar respond by shrinking. From this we would infer that:
the solution is hypertonic
Which of the following is NOT a mechanism for bringing material into a cell?
exocytosis
A bacterial cell that can alter the composition of saturated and unsaturated fatty acids in its membrane lipids is adapted to a cold environment. If this cell is shifted to a warmer environment, it will react by..
increasing the degree of saturated fatty acids in its membrane.
What variable(s) influence(s) whether a nonpolar molecule can move across a membrane by passive diffusion?
the difference in concentration of the molecule across the membrane
Which of the following does NOT contribute to the selective permeability of a biological membrane?
hydrogen bond formation between water and phosphate groups
How are active transport and coupled transport related?
coupled transport uses the concentration gradient established by active transport
A cell can use the process of facilitated diffusion to..
move ions or large polar molecules from a region of high concentration to a region of low concentration
Each compartment of the endomembrane system of a cell is connected to the plasma membrane. Create a simple diagram of a cell, including the RER, Golgi apparatus, vesicle, and plasma membrane. Starting with the RER, use two different colors to represent the inner and outer halves of the bilayer for each of these membranes. What do you observe?
The inner half of the bilayer of the various endomembranes becomes the outer half of the bilayer of the plasma membrane.
The distribution of lipids in the ER membrane is symmetric, that is, it is the same in both leaflets of the membrane. The Golgi apparatus and plasma membrane do not have symmetric distribution of membrane lipids. What kinds of processes could achieve this outcome?
Lipids can be inserted into one leaflet to produce asymmetry. When lipids are synthesized in the SER, they can be assembled into asymmetric membranes. There are also enzymes that can flip lipids from one leaflet to the other.
