Bell Ringer ____H 2 O ____Na 2+

Cell Membrane

Fluid Mosaic Model Cell membrane is thought to be both fluid and a mosaic of phospholipids, proteins and carbohydrates. Fluid  material is capable of flowing, changing shape, and shifting Mosaic  small parts; together form a picture

What is special about FMM? Accounts for movement of molecules across the membrane

Cell Membrane Players Phospholipids Transport proteins Carrier proteins Channel proteins (aka. ion channel) Receptor proteins Marker proteins Cholesterol

1. Phospholipids Consists of: Phosphate group (polar head) Glycerol Backbone Two fatty acids (nonpolar tail)

All Proteins Molecule must fit inside protein in order to permeate the membrane 1. Transport proteins 2. Receptor proteins 3. Marker proteins How are these proteins similar to enzymes? How are these proteins different from enzymes?

1.Transport Proteins a. Carrier proteins Function- move MOLECULES across a membrane Ex. hemoglobin, glucose transporter b. Channel proteins Function-move IONS across the membrane Ex. Potassium channel move molecules or ions across a membrane DOWN their concentration gradient.

a. Carrier Proteins Example 1: hemoglobin transfers O 2

a. Carrier Protein Example 2: Glucose Transporter transports sugar

b. Channel Protein K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ Potassium ions are flowing DOWN their concentration gradient

Passive Transport (3) Simple Diffusion Molecules move from a high to low concentration Osmosis Movement of water from high to low concentration Facilitated diffusion Movement of molecules and ions from a high to low concentration with the help of: Transport proteins- carrier proteins and channel proteins chapter5/how_facilitated_diffusion_works.html

2. Receptor Proteins Receptor Proteins- bind to a specific signal molecule, enabling the cell to respond Function- cell to cell communication to perform action Example: rhodopsin detects light, enabling you to see in dim- light conditions.

3. Marker Proteins Marker Proteins- distinguish cell type; “tags” it Function: helps cells identify other cells Example: MHC class I and II

Cholesterol Cholesterol- type of fatty acid present in the cell membrane of all cells Function: building block to make hormones, vitamin D and other substances that help you absorb nutrients from food you eat.

Lipoproteins: carry cholesterol throughout body HDL- High Density Lipoproteins AKA “good cholesterol” Carries cholesterol back to liver to remove it. For You Information (NOT ON TEST) LDL- Low Density Lipoproteins AKA “bad cholesterol” High levels of LDL means cholesterol builds up in arteries, making heart work harder than it needs to.

Animations For all cell membrane activities… visit the following website: lass/Blair/Cell%20Membrane Diffusion Osmosis Passive Transport Facilitated Diffusion Active Transport