A. nucleotides and nucleosides.
B. enzymes, electron acceptors, and electron donors.
C. fatty acids.
E. lipids, proteins, and carbohydrates.
A. hydrophobic regions within the lipid portion of the bilayer.
B. hydrophilic regions that protrude in aqueous environments on either side of the membrane.
C. lateral but not vertical movement within the bilayer.
D. control over the rate of diffusion.
E. polar regions that interact with similar regions of integral membrane proteins.
A. Both membranes have only peripheral proteins.
B. Only the mitochondrial membrane has integral proteins.
C. Only the mitochondrial membrane has peripheral proteins.
D. All of the proteins from both membranes are hydrophilic.
E. The two membranes differ in their lipid composition.
A. on the inner side of the membrane, facing the cytosol.
B. on the outer side of the membrane, protruding into the environment.
C. on both sides of the membrane.
D. on neither side of the membrane.
E. within the membrane.
A. bilayer, with the fatty acids pointing toward each other.
B. bilayer, with the fatty acids facing outward.
C. single layer, with the fatty acids facing the interior of the cell.
D. single layer, with the phosphorus-containing region facing the interior of the cell.
E. bilayer, with the phosphorus groups in the interior of the membrane.
A. help hold a membrane together.
B. transport ions across membranes.
C. attach to carbohydrates.
D. disrupt membrane function.
E. alter the fluidity of the membrane.
Integral membrane proteins.
peripheral membrane proteins.
A. allowing movement of molecules that would otherwise be excluded by the lipid components of the membrane.
B. transferring signals from outside the cell to inside the cell.
C. maintaining the shape of the cell.
D. facilitating the transport of macromolecules across the membrane.
E. stabilizing the lipid bilayer.
A. DNA cannot function.
B. membranes lack adequate fluidity.
C. photosynthesis is impaired.
D. chloroplasts malfunction.
E. membranes need more cholesterol.
A. a peripheral protein.
B. a transmembrane protein.
C. a phospholipid.
D. an enzyme.
E. entirely outside the phospholipid bilayer.
A. many proteins can move around within the bilayer.
B. all proteins are anchored within the membrane.
C. proteins are asymmetrically distributed within the membrane.
D. all proteins in the plasma membrane are peripheral.
E. different membranes contain different proteins.
A. Integral proteins
B. Channel proteins
C. Peripheral proteins
D. Transmembrane proteins
E. Gated channels
A. only in muscle cell membranes.
B. associated with the fatty acid region of the lipids.
C. in the interior of the membrane.
D. exposed on the surface of the membrane.
E. either on the surface or inserted into the interior of the membrane.
A. increasing the number of cholesterol molecules present.
B. closing protein channels.
C. decreasing the number of hydrophobic proteins present.
D. replacing saturated fatty acids with unsaturated fatty acids.
E. using fatty acids with longer tails.
A. integral membrane proteins.
B. ice crystals.
A. ratio of one protein molecule for every 25 phospholipid molecules.
B. capacity of lipids to associate and maintain a bilayer organization
C. constant fatty acid chain length and degree of saturation.
D. ability of phospholipid molecules to flip over and trade places with other phospholipid molecules.
E. asymmetrical distribution of membrane proteins.
A. some vesicles from the Golgi apparatus fuse with the lysosomes.
B. membrane vesicles carry proteins from the endoplasmic reticulum to the Golgi apparatus.
C. membrane is continually being lost from the plasma membrane by endocytosis.
D. new phospholipids are synthesized in the endoplasmic reticulum.
E. the phospholipids become more tightly packed together in the membrane.
A. Rough ER; Golgi apparatus; vesicle; plasma membrane
B. Golgi apparatus; rough ER; lysosome
C. Lysosome; vesicle; plasma membrane
D. Plasma membrane; coated vesicle; lysosome
E. Rough ER; cytoplasm; plasma membrane
A. glycolipids and glycoproteins.
B. closure of gated channels.
C. the cytoskeleton and lipid rafts.
D. cell adhesion.
E. tight junctions and desmosomes.
D. Fatty acids
A. Gap junctions
B. Tight junctions
D. Cytoplasmic plaques
E. Both a and b