B2.1: Cell Membrane & Transport (Intro)

Front

What is the structure and function of cholesterol in the cell membrane?

Back

Cholesterol is a lipid molecule that is interspersed within the phospholipid bilayer of the cell membrane. It helps to maintain membrane fluidity and stability, making the membrane less permeable to very small water-soluble molecules that might otherwise pass freely through.

Front

What is active transport and how does it differ from passive transport?

Back

Active transport is the movement of molecules across a cell membrane from a region of lower concentration to a region of higher concentration, requiring energy (ATP). In contrast, passive transport does not require energy and occurs along the concentration gradient.

Front

What are the different modes of transport across the cell membrane?

Back

The main modes of transport across the cell membrane include simple diffusion, facilitated diffusion, active transport, endocytosis, and exocytosis.

Front

What occurs during phagocytosis?

Back

During phagocytosis, a cell engulfs solid particles or microorganisms, effectively 'eating' them. This process is a form of endocytosis.

Front

What is the difference between simple diffusion and facilitated diffusion?

Back

Simple diffusion is the movement of small or nonpolar molecules directly through the phospholipid bilayer without assistance, while facilitated diffusion involves the use of transport proteins to help larger or polar molecules cross the membrane.

Front

What role do transport proteins play in the cell membrane?

Back

Transport proteins facilitate the movement of substances across the cell membrane, either by providing a channel for passive transport or by actively transporting molecules against their concentration gradient.

Front

What is the significance of the sodium-potassium pump in cellular function?

Back

The sodium-potassium pump is crucial for maintaining the electrochemical gradient across the cell membrane, which is essential for processes such as nerve impulse transmission and muscle contraction.

Front

How does endocytosis differ from exocytosis?

Back

Endocytosis is the process by which cells take in substances by engulfing them in a vesicle, while exocytosis is the process of expelling substances from the cell by merging vesicles with the cell membrane.

Front

What factors affect the rate of diffusion across a membrane?

Back

The rate of diffusion is affected by factors such as concentration gradient, temperature, surface area, and the permeability of the membrane.

Front

What is osmosis and how does it relate to cell membranes?

Back

Osmosis is the diffusion of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration, affecting cell volume and pressure.