Cell membrane

Transport

membrane controls what molecules enter and exit the cell.

Cell adhesion

Various molecules on the cell membrane connect cells together.

Cell recognition

Some molecules on the cell membrane act as markers.

Cell signaling

Cells send and receive signalling molecules.

Cholesterol

keeps the membrane fluid

The fluid mosaic model

The phospholipids are able to move around. (fluid). The cell membrane contains different types of proteins. A pattern of different molecules mixed together.

Hydrophobic

fear of water

Hydrophilic

attracted to water

Tail

Non polar and hydrophobic

Head

Polar and hydrophilic

How is the cell membrane like a bubble?

• The cell membrane is flexible- it can bend and wiggle

• The phospholipid molecules and proteins are constantly moving around and shifting positions. The cell membrane is fluid.

• The membrane can self-seal

Selectively permeable

Only certain molecules can pass through

Homeostasis

The process of any organism or cell maintaining a balanced and stable internal environment in a changing external environment.

What does the cell membrane do so the cell can function when the outside environment is changing?

Moves materials in and out

What does your body do when It gets to hot?

You sweat and your blood vessels get bigger.

What does your body do when it is too cold?

You shiver, and your blood vessels shrink.

If the sugar in your blood is too high, how does the body respond?

The pancreas releases insulin to help the cells consume the sugar (glucose) so they can make energy.

If the sugar in your blood is too high, what does your body do?

Glucagon is released, which causes the liver to put more glucose into the blood.

Passive transport

The cell does not use energy to transport molecules across the cell membrane.

Concentration gradient

The difference between the concentration of a molecule in one area and its concentration in an adjacent area.

Passive transport

Molecules move from high to low concentration. Moving down the gradient. No energy needed.

Active transport

Molecules move from low to high concentration. Moving up against the gradient. Energy needed.

Simple diffusion

Molecules move down a concentration gradient. From high to low concentration. In simple diffusion, molecules move through the phospholipid bilayer. Small molecules, molecules without a charge.

Facilitated diffusion

Molecules move from high to low concentration through a transport protein. Facilitate means to help/assist. Large molecules like glucose, molecules with a charge, and ions.

Osmosis

The movement of water from high to low concentration. Water can pass slowly through the phospholipid bilayer but also moves through a protein called aquaporin.

When there is a smaller gradient…

Slower diffusion

When there is a larger gradient…

There is faster diffusion