Cell Membranes: Structure and Function (Transport processes)

Question 1

What roles do the proteins and cholestrol play in the cell membrane?

Answer 1

Proteins, particularly those that span the membrane (transmembrane proteins), act as channels and carriers, facilitating the movement of molecules across the membrane.

Cholesterol modulates membrane fluidity, preventing the membrane from becoming too rigid at lower temperatures and too fluid at higher temperatures.

Question 2

What role does the cell membrane have?

Answer 2

Also known as the plasma membrane, plays a crucial role in protecting the cell, regulating what enters and exits, and facilitating communication between cells

Question 3

What is meant by the term ‘Selectively Permeable’?

Answer 3

Selectively permeable means some substances are able to pass through the membrane, while other substances are not able to pass through.

The cell membrane is considered to be selectively permeable since it selects what is able to pass through.

Question 4

What types of molecules are permeable and Impermeable?

Answer 4

Generally, small, nonpolar molecules (like oxygen and carbon dioxide) and small, uncharged polar molecules (like water) can pass through membranes, while larger, polar molecules (like glucose) and charged molecules (like ions) often require transport proteins or cannot pass freely.

Question 5

Why do cells need to be microscopic in size? Relate this to their SA:V

Answer 5

Cells need to be microscopic because a higher surface area to volume (SA:V) ratio is crucial for efficient exchange of materials (nutrients, waste, gases) with the environment.