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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