Membrane Structure & Function

Question 1

Describes the plasma membrane as a dynamic structure composed of a phospholipid bilayer with embedded proteins that move laterally within the layer.

Answer 1

Fluid Mosaic Model

Question 2

Hydrophobic (water-repelling) tails face inward, away from water, and hydrophilic (water-attracting) heads face outward, interacting with the aqueous environment inside and outside the cell.

Answer 2

Phospholipid Bilayer

Question 3

Form pores in the membrane, allowing specific ions or molecules to pass through (e.g., ion channels for K⁺ and Na⁺).

Answer 3

Channel Proteins

Question 4

Bind to specific molecules and undergo conformational changes to transport them across the membrane.

Answer 4

Carrier Proteins

Question 5

Bind to signaling molecules (e.g., hormones), initiating cellular responses.

Answer 5

Receptor Proteins

Question 6

Movement of molecules down their concentration gradient (from high to low concentration) without energy. Includes simple diffusion, facilitated diffusion, and osmosis.

Answer 6

Passive Transport

Question 7

Requires ATP to move molecules against their concentration gradient. Example: Sodium-potassium pump.

Answer 7

Active Transport

Question 8

The cell membrane engulfs material, forming a vesicle to bring it into the cell.

Answer 8

Endocytosis

Question 9

Vesicles fuse with the membrane to release contents outside the cell.

Answer 9

Exocytosis