Biological Membranes and Transport

Question 1

amphipathic molecules

Answer 1

All of the lipid molecules in cell membranes are amphipathic (or amphiphilic)—that is, they have a hydrophilic (“water-loving”) or polar end and a hydrophobic (“water-fearing”) or nonpolar end. The most abundant membrane lipids are the phospholipids. These have a polar head group and two hydrophobic hydrocarbon tails.

Question 2

liposome

Answer 2

spherical vesicle having at least one lipid bilayer

Question 3

all transmembrane proteins are also know as

Answer 3

integral membrane proteins

Question 4

a phospholipid with cholesterol has w flexible or rigid membrane

Answer 4

rigid

Question 5

a sphingolipid with cholesterol has a flexible or rigid membrane

Answer 5

flexible

Question 6

exocytosis

Answer 6

intracellular vesicle moves to the plasma membrane and subsequent fusion of the vesicular membrane and plasma membrane ensues

Question 7

endocytosis

Answer 7

cells absorb molecules by engulfing them

Question 8

Flippase

Answer 8

moves a membrane lipid from the outside layer to the inside layer, uses ATP

Question 9

Floppase

Answer 9

moves a membrane lipid from the inside layer to the outside layer, uses ATP

Question 10

Scramblase

Answer 10

moves one membrane lipid out and one in, uses Ca++