Plasma Membrane

Identify cholesterol molecule

• structure a

• structure b

• structure h

• structure i

Identify a peripheral protein

• structure a

• strucure b

• structure g

• structure h

Plasma membranes are selectively permeable. This means

• anything can pass in and out

• the membrane regulates the passage of the material in and out of the cell

• glucose cannot enter the cell

• cholesterol cannot enter

Which is NOT a function of the membrane?

• it forms a selective barrier

• it has receptors for chemical messages

• it is the control center of the cell

• it is involved in self recognition

Small, nonpolar, hydrophobic molecules such as fatty acids

• easily pass through the membrane's bilayer

• very slowly diffuse through the bilayer

• require transport proteins

• enter through endocytosis

Membrane phospholipids

• have hydrophobic heads that face the center of the membrane and are shielded from water

• have hydrophilic tails that face outward

• remain fluid because they are tightly packed

• none of these

Which of the following substances would have the most trouble crossing the membrane by diffusing through the bilayer?

• water

• oxygen

• carbon dioxide

• a sodium ion

The cholesterol associated with membranes

• is attached to proteins and extends into the environment surrounding the cell

• helps stabilize the membrane at body temperature

• is an abnormality resulting from a diet high in cholesterol

• both a and c

A major function of glycoproteins and glycolipids in the membane is to

• glue cells together to form tissues

• allow cells to identify each other

• attach membrane to cytoskeleton

• help retain shape

When doctors perform organ transplants, they choose a donor tissue match. Which component is being matched?

• membrane phospholipids

• cytoskeleton

• cell surface carbohydrates

• cholesterol