Structure Made of Composed of Has Function Can Used for Allows for

Structure or Function Selectively transports Flexible Selectively permeable Controls what enters and leaves cell Fluid mosaic like in that the molecules can move past each other Communicates with other cells through cell signaling Hydrophilic on the outside, hydrophobic inside Serve to identify other cells and molecules Function Provides support and protection Is made of cholesterol, phospholipid, protein, carbohydrate molecules Secretes cell products Excretes waste products Maintains a barrier from the outside environment Helps to maintain cellular homeostasis Provides channels for molecules to move through

Vocabulary for today Semipermeable/Selectively Permeable/ Selective Permeability Cell Membrane/ Plasma Membrane Phospholipid Molecule Fluid Mosaic Model Receptor Homeostasis Transport

In order to survive a cell must : 1. Be Protected from the outside environment 2. Interact with and respond to changes in the outside environment

KEY CONCEPTS : The cell membrane regulates what enters and leaves the cell.

The cell membrane is important in maintaining a homeostatic balance between the cell and its environment.

The Cell Membrane has three major functions Protective boundary Regulate movement of materials into and out of the cell 3. Communicate with other cells cell membrane outside cell inside cell

What do you think gives the membrane its ability to carry out these functions? a. Size b. Shape c. Structure Structure

Cell Membrane Structure The cell membrane is made of different types of molecules: Phospholipids Cholesterol Proteins Carbohydrates cell membrane protein cholesterol carbohydrate chain protein channel

Membrane Molecule and their Functions

3 Parts of a Phospholipid: Phosphate molecule Glycerol 1. Phospholipids #1 molecule – makes up 75% of the cell membrane 3 Parts of a Phospholipid: Phosphate molecule Glycerol 2 Fatty acid chains

The phospholipids are arranged into a bilayer Phospholipid Bilayer Hydrophobic and Hydrophilic Parts of Membrane

2. Cholesterol (lipid) Provides strength to the membrane by making it flexible

3. Proteins Transport materials across the membrane Anchor the cytoskeleton Serve as chemical receptors Enzymes needed to speed up chemical reactions

4. Carbohydrates Identification tags Provides chemical communication between cells

‘Fluid Mosaic Model”describes the membrane structure

The Cell Membranes’ most important property is Selectively Permeability – allowing select substnaces to pass through .

Selective Permeability allows the cell to maintain Homeostasis- a steady internal state regardless of changing conditions outside the cell.

Charge (positive, negative, neutral) Whether a molecule passes thru the membrane depends on its Size Charge (positive, negative, neutral) Concentration differences inside/outside of cell If a transport molecule is available Shape

Examples of General Rules of Movement Examples: Small, non polar molecules ______________________ Small, polar molecules__________________________ Large molecules ______________________________

Small, non polar molecules move easily through on their own Small, polar molecules__________________________ Large molecules ______________________________

Examples of Rules of General Movement: Small, non polar molecules move easily through on their own Small, polar molecules must be moved through with the help of transport proteins Large molecules ______________________________

* Small, non polar molecules – easily move through membrane on their own. * Small, polar molecules - moved through membrane by transport proteins Large molecules Moved across membrane inside vesicles

Cell Signalling Key Idea: Cells use chemical molecules to communicate with each other and their outside environment Examples of “chemical signals”: * Hormones * Insulin * Medicines * Growth Factors * Neurotransmitters (chemicals that stimulate the nervous system) * Chemicals that make food smells, flower scents

Cell Signalling The chemical “messenger” is called a ligand Cell Signalling The chemical “messenger” is called a ligand. The chemical “receiver” is called a receptor and is often a protein molecule.

When a ligand and receptor bind they change shape which causes a series of changes in the cell.

. Two types of receptors. Intracellular receptors – inside the cytoplasm

. Two types of receptors. Intracellular receptor – inside the cytoplasm Membrane receptor – inside the membrane

Cell Communication is Vital to keeping the body ALIVE! STRESS RESPONSE

Diseases caused by Cell Membrane Abnormalities Cystic Fibrosis – defective protein channel in the membrane which doesn’t allow calcium into cell and results in an excessive production of fluid in lungs and digestive system. Makes it hard to get oxygen and food. http://www.dnatube.com/video/6196/Cystic-fibrosis-is-caused-by-dysfunctional-protein Alzheimer’s – stiff fatty acids used in brain cell membranes Diabetes- Lack of insulin receptors in membrane