transports

What does it mean for biological membranes to be selectively permeable?

They only allow certain things to pass in and out.

What determines what can easily pass through a membrane?

The properties of the molecule (nonpolar, polar, charged) and its size.

What types of molecules can pass through a membrane without needing assistance?

Small nonpolar molecules, such as oxygen, carbon dioxide, and steroids.

Which molecules require transporter proteins to cross the membrane?

Small uncharged polar molecules, large polar molecules, and charged ions.

What is diffusion?

The movement of substances from high concentration to low concentration.

What is facilitated diffusion?

A type of diffusion that requires protein assistance to help molecules cross the membrane.

What are the two types of diffusion mentioned?

Simple diffusion (direct passage through the membrane) and facilitated diffusion (requires proteins).

What is active transport?

The movement of substances from low concentration to high concentration, requiring energy.

What is osmosis?

The movement of water across a membrane, specifically from low solute concentration to high solute concentration.

What is the role of aquaporin?

It is a channel protein that facilitates the rapid movement of water across the cell membrane.

How does water move in terms of solute concentration?

Water moves from the side with less solute concentration to the side with more solute concentration.

What are hypotonic, isotonic, and hypertonic solutions in relation to cell concentration?

Hypotonic has lower solute concentration outside the cell, isotonic has equal concentrations, hypertonic has higher solute concentration outside the cell.

What happens to a cell in a hypertonic solution?

Water moves out of the cell, causing it to shrink.

What happens to a cell in a hypotonic solution?

Water moves into the cell, causing it to swell.

What is the concentration gradient?

The difference in concentration of substances across a space.

What is passive diffusion?

The process that occurs naturally from high concentration to low concentration without energy input.