Bell Ringer____H2O

____Na2+

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

https://www.youtube.com/watch?v=LKN5sq5dtW4

What is special about FMM?

Accounts for movement of molecules across the membrane

Cell Membrane PlayersPhospholipids

Transport proteinsCarrier proteinsChannel proteins (aka. ion channel)

Receptor proteins

Marker proteins

Cholesterol

1. PhospholipidsConsists 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 ProteinsExample 1: hemoglobin transfers O2

a. Carrier ProteinExample 2: Glucose Transporter transports sugar

b. Channel Protein

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

OsmosisMovement 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

http://highered.mheducation.com/sites/9834092339/student_view0/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 cellsExample: 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:

http://www.town.hull.ma.us/public_documents/hullma_highschclass/Blair/Cell%20Membrane

Diffusion

Osmosis

Passive Transport Facilitated Diffusion

Active Transport