Unit 2 - Cell Membrane WHS

Other names for the cell membrane

Plasma Membrane

Phospholipid Bilayer

Fluid Mosaic Model

What are the components of a phospholipid

Phosphate, glycerol, and two fatty acids

The phosphate heads are ___________

Hydrophilic / Polar

Define hydrophilic

Water loving

The fatty acid tails are ________

Hydrophobic / Nonpolar

Define hydrophobic

Water fearing/ water repelling

Why do phospholipids form a bilayer?

The hydrophobic fatty acid tails point inwards so that they are not exposed to water. The hydrophilic phosphate heads are on the outside because they like the water.

What are the four main components of the cell membrane?

Carbohydrates, proteins, cholesterol, and the phospholipid bilayer.

Where are the carbohydrates, proteins, and cholesterol?

They are embedded in the membrane.

What is the function of the carbohydrates?

Carbohydrates are identification tags

What is the function of the proteins?

Proteins help materials cross the membrane

What is the function of cholesterol?

Cholesterol provides structure and support

What are two functions of the cell membrane?

It controls the passage of materials in and out of the cell.

It provides a barrier between cells and the environment.

Define selectively permeable/ semi-permeable membrane

Some molecules can cross the membrane but others cannot.

What kinds of molecules can cross the cell membrane?

Small, non-charged molecules and lipid-soluble molecules.

What types of materials does the cell need to move into the cell?

Glucose, water, and oxygen

What types of materials does the cell need to move out of the cell?

Wastes such as carbon dioxide and excess water.

Why do cells move molecules in and out of cells?

In order to maintain homeostasis even with unpredictable changing conditions outside the cell.

Molecules move across the cell membrane because of the ____________ ___________.

Concentration gradient

Define concentration gradient

The difference in concentration of one substance from one location to another

Define dynamic equilibrium

The concentration of molecules is the same throughout the solution (equilibrium) but the molecules continue to move (dynamic)

Define diffusion

The movement of molecules from an area of high concentration to an area of lower concentration. This can occur through the cell membrane.