The Cell Membrane Functions 1)The cell membrane regulates what enters and leaves the cell. 2)The cell membrane provides protection and support for the cell. 3) Communicate with other cells. The cell membrane acts as a BARRIER, separating the cell’s inside from its outside.

The cell membrane is also known as the plasma membrane, and is often referred to as the semi-permeable membrane - allows some materials in, but not all (like a screen or a net).

The cell membrane is made out of a structure called the phospholipid bilayer. Bilayer= double layer.

What is a phospholipid? A phospholipid is a lipid with a phosphate group attached. Notice that there is a polar group attached to the phosphate. Polar= attracted to water (hydrophilic) Nonpolar= repelled by water (hydrophobic)

Heads and Tails The heads of phospholipids love water – hydrophilic. The tails of phospholipids hate water - hydrophobic

Question: What surrounds each side of the cell membrane? Answer: Water based fluids.

The water loving “heads” face the water. The water hating “tails” hide from the water. This helps keep the integrity of the cell membrane (helps keep it “glued” together”). - Small molecules can diffuse through the membrane (including water). - Bigger molecules need proteins to help get in or out of the cell.

The Fluid Mosaic Model Model proposed by S.J. Singer. A mosaic is a work of art made of different colored or textured tiles assembled to form a picture or design. The term “fluid mosaic model” is used to describe the structure of the cell membrane. This is because there are so many different molecules attached to the cell membrane, so it forms a “mosaic”.

3 Key Proteins in the Plasma Membrane Transport Proteins are responsible for moving materials in and out of the cell. They can be used in both passive and active transport.

3 Key Proteins in the Plasma Membrane Marker Proteins are like nametags that identify the cell. One of the functions of marker proteins is to enable a person's immune system to distinguish its cells from those of invading cells. Your body needs to be able to identify “self” from “non-self”. Non-self cells need to be identified and destroyed. Your own cells can tell the difference because of certain recognition proteins in the cell membrane or because of the carbohydrates attached to the proteins enabling them to be recognition proteins.

3 Key Proteins in the Plasma Membrane Receptor Proteins allow the cell to interact and communicate with other cells by picking up signals from other cells. They are “sensitive” to chemical molecules in the extracellular fluid. These molecules could be harmful to the cell or they could be hormones.

Let’s Review! http://glencoe.mheducation.com/sites/0078802849/student_view0/unit2/chapter7/section2/self-check_quizzes-english.html

Parts of the Eukaryotic Cell Reviews fluid mosaic model (first 2 min) and cell parts (last 3 min) https://www.youtube.com/watch?v=PhRiKU6nYk0