BIO122 FINAL TEST 20/21 CHAPTER 6

Plasma membrane is thin barrier, about 8 nm thick. What is the significance of this thickness membrane?

Which of the following is true of integral membrane proteins

• They serve only a structural role in membranes

• They lack tertiary structure

• They are not mobile within the bilayer

• They are usually transmembrane proteins.

When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids. In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are

• integral proteins.

• cholesterol molecules.

• peripheral proteins

• phospholipids.

Which of these are not embedded in the lipid bilayer at all?

• integral proteins

• glycoproteins

• peripheral proteins

• transmembrane proteins

Which of the following, is most important for the glycoproteins and glycolipids of animal cell membranes?

• active transport of molecules against their concentration gradients

• facilitated diffusion of molecules down their concentration gradients

• maintaining the integrity of a fluid mosaic membrane

• a cell's ability to distinguish one type of neighboring cell from another

Name the 3 main component of Plasma Membrane

Give the characteristic of Plasma Membrane...in one word only.

Why are lipids and proteins free to move laterally in membranes?

• There are only weak hydrophobic interactions in the interior of the membrane.

• The interior of the membrane is filled with liquid water.

• Molecules such as cellulose can pull them in various directions

• Hydrophilic portions of the lipids are in the interior of the membrane

The cytoplasmic membrane could best be described as

• slightly permeable to water but impermeable to metabolic solutes

• a highly selective permeability barrier.

• an impermeable barrier.

• a passive conduit for intracellular transport.

Which of the following best describes the structure of the plasma membrane?

• a single layer of lipids with proteins embedded in it

• a single layer of proteins

• a double layer of lipids with proteins embedded in it

• a double layer of proteins