Cell Membrane

What is the plasma membrane made of?

A phospholipid bilayer and floating proteins

What is the "fluid mosaic model"?

A description of the cell membrane where proteins float in a fluid-like phospholipid bilayer

How thick is the plasma membrane?

6–8 nanometers thick

What are some examples of intracellular membranes?

• Endoplasmic reticulum

• Mitochondrial membranes

• Nuclear envelope

Why is it called a "mosaic"?

Because of the scattered proteins embedded like tiles in the membrane

What does the plasma membrane do?

It protects the cell, controls what enters and exits, and organizes internal functions

What are the sugar side chains on membrane proteins and lipids for?

For cell-to-cell interactions and communication

What does cholesterol do in the membrane?

Stabilizes the membrane and maintains proper fluidity

What gives the membrane its antigenicity?

The proteins in the membrane

What is selective permeability?

The membrane controls what enters and leaves the cell, and how much

What are the two main types of membrane transport?

Passive transport and active transport

Does active transport require energy?

Yes, it needs energy (usually ATP)

Is the plasma membrane rigid?

No, it is flexible and elastic