Cell Membrane Transport Quiz

Cell Membrane Transport

• 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.

Passive 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.

Types of Osmosis Solutions

• 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.

Osmolarity

• Refers to the number of solute particles per liter of solution.

Dialysis

• 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.

Facilitated Diffusion: Transport Proteins

• 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.

Active Transport

• Requires energy to move substances across the membrane.
• This includes pump transport and vesicle transport.

Active Transport: Pump Transport

• 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.