Major Structural Components of the Cell Membrane

Which of the following types of molecules are the major structural components of the cell membrane?
A) phospholipids and cellulose
B) nucleic acids and proteins
C) phospholipids and proteins
D) proteins and cellulose
E) glycoproteins and cholesterol

For the following questions, match the labeled component of the cell membrane (Figure 7.1) with its description.

[pic]

Figure 7.1

5) peripheral protein

6) cholesterol

9) glycolipid

11) The presence of cholesterol in the plasma membranes of some animals
A) enables the membrane to stay fluid more easily when cell temperature drops.
B) enables the animal to remove hydrogen atoms from saturated phospholipids.
C) enables the animal to add hydrogen atoms to unsaturated phospholipids.
D) makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.
E) makes the animal more susceptible to circulatory disorders.

12) According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
A) They can move laterally along the plane of the membrane.
B) They frequently flip-flop from one side of the membrane to the other.
C) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane.
D) They are free to depart from the membrane and dissolve in the surrounding solution.
E) They have hydrophilic tails in the interior of the membrane.

13) Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
A) by increasing the percentage of unsaturated phospholipids in the membrane
B) by increasing the percentage of cholesterol molecules in the membrane
C) by decreasing the number of hydrophobic proteins in the membrane
D) by co-transport of glucose and hydrogen
E) by using active transport

14) In order for a protein to be an integral membrane protein it would have to be which of the following?
A) hydrophilic
B) hydrophobic
C) amphipathic
D) completely covered with phospholipids
E) exposed on only one surface of the membrane

[pic]

Figure 5.7

51) The structure depicted in Figure 5.7 shows the
A) 1-4 linkage of the 〈 glucose monomers of starch.
B) 1-4 linkage of the ® glucose monomers of cellulose.
C) double helical structure of a DNA molecule.
D) 〈 helix secondary structure of a polypeptide.
E) ® pleated sheet secondary structure of a polypeptide.

52) Figure 5.7 best illustrates the
A) secondary structure of a polypeptide.
B) tertiary structure of a polypeptide.
C) quaternary structure of a protein.
D) double helix structure of DNA.
E) primary structure of a polysaccharide.

53) The tertiary structure of a protein is the
A) bonding together of several polypeptide chains by weak bonds.
B) order in which amino acids are joined in a polypeptide chain.
C) unique three-dimensional shape of the fully folded polypeptide.
D) organization of a polypeptide chain into an 〈 helix or ® pleated sheet.
E) overall protein structure resulting from the aggregation of two or more polypeptide subunits.

54) A strong covalent bond between amino acids that functions in maintaining a polypeptide's specific three-dimensional shape is a (an)
A) ionic bond.
B) hydrophobic interaction.
C) van der Waals interaction.
D) disulfide bond.
E) hydrogen bond.

55) At which level of protein structure are interactions between the side chains (R groups) most important?
A) primary
B) secondary
C) tertiary
D) quaternary
E) all of the above

The function of each protein is a consequence of its specific shape. What is the term used for a change in a protein's three-dimensional shape or conformation due to disruption of hydrogen bonds, disulfide bridges, or ionic bonds?
A) hydrolysis
B) stabilization
C) destabilization
D) renaturation
E) denaturation