Cell Membrane Structure and Function

Why are raw eggs, rather than hard-boiled eggs, used in the egg osmosis lab after the shell is removed?

• Raw eggs are easier to handle without a shell.

• The membrane of a raw egg mimics a semi-permeable cell membrane.

• Hard-boiled eggs would absorb too much vinegar.

• The yolk of a hard-boiled egg would interfere with osmosis.

What is the primary reason cells are typically very small?

• Smaller cells require less energy to maintain.

• Small size allows for a large surface area to volume ratio, facilitating efficient transport.

• Larger cells are more susceptible to damage.

• Small cells can divide more rapidly.

Which of the following statements about cell membranes is correct?

• Only animal cells possess a cell membrane.

• Cell membranes are found in all living organisms.

• Plant cells have a cell wall but lack a cell membrane.

• Viruses are the only organisms that do not have a cell membrane.

What does the "fluid" aspect of the Fluid Mosaic Model of the cell membrane imply?

• The membrane is primarily composed of water.

• Components of the membrane are constantly moving.

• The membrane can change its shape to engulf substances.

• The membrane allows all fluids to pass through freely.

What characteristic allows phospholipids to form a bilayer in aqueous environments?

• Their entirely nonpolar composition.

• Their ability to actively transport water molecules.

• Their amphiphilic nature, possessing both hydrophilic and hydrophobic regions.

• Their rigid, crystalline structure.

What does the fluid mosaic model imply about the structure and behavior of the cell membrane?

• The membrane is a static, rigid barrier that prevents all molecular movement.

• Components of the membrane, such as phospholipids, are able to move laterally, contributing to its flexibility.

• Only water molecules can freely pass through the membrane, while other substances are strictly excluded.

• The membrane is primarily composed of a solid protein matrix with embedded lipids.

How does cholesterol contribute to the dynamic stability of the cell membrane across varying temperatures?

• It acts as a primary energy source, fueling membrane transport processes.

• It forms selective channels that regulate the passage of ions.

• It prevents phospholipids from packing too tightly at low temperatures and from becoming too fluid at high temperatures.

• It serves as a receptor for hormones, initiating intracellular signaling.

What is a key functional difference between integral and peripheral proteins within the cell membrane?

• Peripheral proteins are permanently embedded in the lipid bilayer, while integral proteins are loosely associated with the membrane surface.

• Integral proteins primarily provide structural support, whereas peripheral proteins are mainly involved in cell-to-cell adhesion.

• Integral proteins often span the entire membrane and facilitate transport, while peripheral proteins are typically found on the membrane's surface and can be involved in enzymatic activities or cytoskeleton attachment.

• Peripheral proteins are responsible for maintaining membrane fluidity, while integral proteins regulate cholesterol levels.