Cell Membrane Structure and Transport

These flashcards cover key concepts regarding the structure and function of the cell membrane, including transport mechanisms and protein functions.

What is the primary structure of the cell membrane?

A phospholipid bilayer.

What contributes to the fluidity of the cell membrane?

Cholesterol.

What is the hydrophilic part of a phospholipid called?

The phosphate head.

How do the lipid tails of phospholipids behave in relation to water?

They are hydrophobic and repel water.

What term describes molecules that have both hydrophilic and hydrophobic regions?

Amphipathic.

What role do integral proteins serve in the cell membrane?

They are embedded in the membrane and have various functions including acting as channels.

What is the function of channel proteins?

To selectively allow specific materials to pass into or out of the cell.

What are glycoproteins?

Proteins that have carbohydrate molecules attached.

What is the glycocalyx?

A fuzzy coating around the cell formed from glycoproteins and carbohydrates.

Define passive transport.

Movement of substances across the membrane without the expenditure of cellular energy.

What is facilitated diffusion?

The process where substances cross the cell membrane with the help of proteins.

What is osmosis?

The diffusion of water through a semipermeable membrane.

What is the difference between hypertonic and hypotonic solutions?

Hypertonic has a higher solute concentration than another solution, while hypotonic has a lower solute concentration.

What is active transport?

The movement of substances across a membrane that requires energy, usually against their concentration gradient.

What is the sodium-potassium pump?

An active transport protein that moves sodium out and potassium into the cell, consuming ATP.

What occurs during endocytosis?

A cell ingests material by enveloping it in a portion of its cell membrane.

What is phagocytosis?

A type of endocytosis involving the ingestion of large particles.

How does receptor-mediated endocytosis differ from regular endocytosis?

It is selective and involves receptors binding specific ligands.

What is exocytosis?

The process of exporting materials out of the cell using vesicular transport.

What are the two methods of transport categorized based on energy?

Passive transport and active transport.

What do membrane proteins provide in terms of cell function?

They perform specific functions such as signaling, transport, and acting as receptors.

What defines a concentration gradient?

The difference in concentration of a substance across a space.

What does selective permeability mean?

The ability of the cell membrane to allow certain substances to pass while excluding others.

What happens during simple diffusion?

Molecules move from an area of higher concentration to an area of lower concentration.

How does temperature affect diffusion rates?

Higher temperatures increase the rate of diffusion due to increased molecular movement.

What are symporters and antiporters in the context of cell transport?

Symporters move two substances in the same direction, while antiporters move substances in opposite directions.

Why are sodium ions not able to diffuse directly through the cell membrane?

They are charged and are repelled by the hydrophobic tails of the membrane.