Cell Membrane Transport Quiz

Study Notes

The cell membrane is a barrier that regulates the movement of substances into and out of the cell.
Transport proteins embedded in the membrane facilitate this movement.
These proteins act as channels or pumps to maintain a balance of salts, nutrients, and proteins inside the cell.
There are two main types of transport: passive and active transport.

Occurs when substances move across the membrane without the cell expending energy.
This includes simple diffusion, osmosis, and facilitated diffusion.
Simple diffusion: Movement of substances from an area of high concentration to an area of low concentration.
Osmosis: Movement of water molecules across a selectively permeable membrane from a dilute solution to a more concentrated one.
Facilitated Diffusion: Movement of substances across the membrane with the assistance of transport proteins.

Isotonic: Equal solute concentration inside and outside the cell.
Hypertonic: Higher solute concentration outside the cell than inside. This causes the cell to shrink.
Hypotonic: Higher solute concentration inside the cell than outside. This causes the cell to swell and potentially burst.

Separation of substances in solution by selective diffusion through a semipermeable membrane.
This is used to remove excess fluids, electrolytes, waste products, and toxins from the blood.

Channel Proteins form pores that allow water molecules and small ions to pass through the membrane.
Carrier Proteins bind to specific ions or molecules and change shape to transport them across the membrane.

Primary Active Transport uses ATP to move ions across the membrane, creating a charge difference.
Sodium-potassium pump is an example of primary active transport, pumping potassium into the cell and sodium out.
Secondary Active Transport uses the energy stored in concentration gradients (created by primary active transport) to move other substances.
Sodium-glucose transporter is an example of secondary active transport, using the sodium concentration gradient to bring glucose into the cell.