Mechanisms of Transport Across the Cell Membrane

What are the characteristics of freely permeable membranes?

Freely permeable membranes allow any substance to pass without difficulty.

What distinguishes selectively permeable membranes from impermeable membranes?

Selectively permeable membranes permit the passage of some materials while preventing others, whereas impermeable membranes do not allow anything to pass.

What does the term permeability refer to in the context of cell membranes?

Permeability determines which substances can cross the membrane.

What are the types of membrane transport mechanisms?

The types of membrane transport mechanisms are passive (e.g., diffusion, carrier-mediated transport) and active (e.g., vesicular transport).

What is diffusion in biological terms?

Diffusion is the movement of ions or molecules driven by concentration differences.

What is osmosis?

Osmosis is the net diffusion of water across a selectively permeable membrane.

Define tonicity and its three effects on cells.

Tonicity is the effect of osmotic solutions on cell volume, with three effects: isotonic (no effect), hypotonic (causes swelling), and hypertonic (causes shrinking).

What is the primary function of the sodium-potassium exchange pump?

The sodium-potassium exchange pump ejects sodium ions and recaptures potassium ions, critical for maintaining homeostasis within the cell.

What is the difference between active transport and facilitated diffusion?

Active transport requires energy (ATP) and can move substances against their concentration gradient, while facilitated diffusion does not require ATP and only moves substances along their concentration gradient.

What are the two major types of vesicular transport?

The two major types of vesicular transport are endocytosis and exocytosis.

What is the process of receptor-mediated endocytosis?

Receptor-mediated endocytosis occurs when materials in the extracellular fluid bind to specific receptors on the membrane, leading to the formation of endosomes.

What happens to a cell placed in a hypotonic solution?

A cell in a hypotonic solution will swell and may burst due to water entering the cell.

How does temperature influence diffusion rates?

Temperature is directly related to diffusion rates; as temperature increases, the rate of diffusion also increases.

What is the role of carrier proteins in transport mechanisms?

Carrier proteins facilitate the transport of hydrophilic or large molecules across the cell membrane.

What is the definition of osmotic pressure?

Osmotic pressure is the force indicating how much water would move into a solution with a higher solute concentration.

What are the three types of carrier-mediated transport?

The three types are facilitated diffusion, active transport, and secondary active transport.