Today’s Data Here Objective Here!

Brainteaser Where do you find roads without vehicles, forests without trees, and cities without houses?

Bell Work Which numbered organelle produces ATP and is called the Powerhouse of the cell? A) 1 B) 7 C) 9 D) 13

Let’s Review

Maintaining control of the internal environment The plasma membrane

Today you will learn The structure of the plasma membrane How the plasma membrane functions as a semi-permeable membrane

What is the Plasma Membrane? The membrane separates the organelles of the cell from the outside environment It is made of a double layer of phospholipids and embedded proteins.

What does the plasma membrane do? Controls what enters and leaves the cell. Nutrients Waste It is said to be selective permeability (Everything CANNOT enter the cell) Water can freely enter and leave the cell Maintains homeostasis

The plasma membrane acts as a gatekeeper.

What is the plasma Membrane made of? There are 3 types of lipids (fats) Phospholipids Glycolipids Cholesterol Proteins Integral (glycoprotein) Peripheral

Structure of plasma membrane Made of lipids (fats) with a phosphate head Lipid portion is 2 fatty acid tails. The tail is hydrophobic: does NOT like water Phosphate head is hydrophilic: it DOES like water. phospholipid

Fluid Mosaic Model Cholesterol embedded in membrane keeps it fluid The bi-layer is known as the Fluid Mosaic Model, because proteins embedded in the membrane can move

Fluid Mosaic Model Here is what a phospholipid bi-layer looks like as a sphere

How do materials move into and out of the cell? Materials must move in and out of the cell through the plasma membrane. Some materials move between the phospholipids. Some materials move through the proteins.

How do materials move into and out of the cell? Some proteins span membrane and determine which molecules can enter or leave. These are transport proteins. Other proteins on the surface act as receptors

The Proteins of the Plasma Membrane 1) Channel Proteins 2) Carrier Proteins 3) Enzymatic Proteins 4) Receptor Proteins 5) Cell Recognition Proteins

1) Channel Proteins Have channels that allow molecules to move from an area of high concentration to an area of low concentration. NO energy is used

2) Carrier Proteins Carrier Proteins – combine with a molecule to help it move across the membrane

3) Enzymatic Proteins – Carry out metabolic reactions

4) Receptor Proteins Receptor Proteins– Have a binding site for a specific molecule.

5) Cell Recognition Proteins Marker Proteins–extend across the cell membrane and serve to identify the cell. The immune system uses these proteins to tell friendly cells from foreign invaders. They are as unique as fingerprints. They play an important role in organ transplants. If the marker proteins on a transplanted organ are different from those of the original organ the body will reject it as a foreign invader.

The plasma membrane is said to be Selectively Permeable

Let’s Review!!! What is the function of the cell/plasma membrane? What is the membrane made of? The membrane is said to be ________________ What is the name of the model? How can molecules enter the cell?

Now build your own! http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap1101

How well did you do today? Cell membranes are constructed mainly of: A. lipid bi-layers B . Protein pumps C. carbohydrate gates D. chloroplast