1.3 Membrane Structure

Question 1

What is a single phospholipid molecule composed of?

Answer 1

Hydrophilic, polar phosphate head and a hydrophobic, non-polar hydrocarbon tail.

Question 2

How do the hydrophobic and hydrophilic properties of the phospholipid bilayer allow a membrane to maintain its structure?

Answer 2

When phospholipids are mixed with water, the phosphate heads are attracted to the water while the hydrocarbon tails are attracted to each other, but not water. This causes the phospholipids to form a bilayer with tails facing each other and heads facing the water on the outside and inside of the cell.

Question 3

Function of channel/carrier proteins?

Answer 3

passive transport across the membrane

Question 4

function of protein pumps?

Answer 4

active transport across membrane

Question 5

function of receptor proteins?

Answer 5

hormone binding and recognition

Question 6

function of enzymes?

Answer 6

used in cell surface reactions

Question 7

function of adhesion proteins?

Answer 7

binding cell together

Question 8

function of neurotransmitter receptors?

Answer 8

communication between cells

Question 9

Differentiate between integral and peripheral proteins.

Answer 9

-Integral proteins are at least partly hydrophobic on their surface and are found embedded in the hydrocarbon chains of the phospholipids. -Peripheral proteins are usually hydrophilic on their surface and are not embedded throughout the membrane.

Question 10

What is the function of glycoproteins in the plasma membrane? Cholesterol?

Answer 10

-Glycoproteins give structural support to cells -Cholesterol forms the outer coating of cells

Question 11

Label the fluid mosaic model.

Answer 11

a. glycoprotein
b. glycolipid
c. receptor protein
d. phospholipid tails
e. phospholipid bilayer
f. phospholipid heads
g. peripheral membrane protein
h. cholesterol
i. integral membrane protein/protein channel

Question 12

What is the chemical components of a phospholipid?

Answer 12

Phosphate tip of the head attached to glycerol group. Glycerol group ties into hydrocarbon tails. Tails bent at double bonds between carbons.