Warm-up

What are the 3 components of cell theory?

Balloon with vanilla

Explore---In groupsA Family has 2 petsLarge dog

Nice and sweetBut behaves poorly if no one is watchingTears up the yard…terrorizes catsBarks until everyone hates him

Little CatEveryone loves this cat…she’s purrrrfect!

Your job…next slide

Your Job Come up with a solution for the pet ownersThe dog can’t go outside unless the owners

are homeThe cat can come and go as she pleases

Keep in mind that the dog is 2.5ft tall….the cat is about 8 inches tall

Be very specific about the size and location of your solution

The Plasma (Cell) Membrane

Plasma Membrane Maintaining Balance

Separates living cell from nonliving environment

Allows steady flow of nutrients in an out of cellHomeostasis

Maintain the cell’s environmentSelective permeability

Allows some molecules into the cell while keeping others out

Structure of Phospholipid BilayerTwo layers of

phospholipids back to back

Lipid with a phosphate group attached

PhospholipidHead is polar –

interact with aqueous external environment (loves water = Hydrophilic)

Tails are non polar – avoid water, afraid of water = Hydrophobic

Water – soluble molecules will not pass through easily

Phospholipid Bilayer

polarhydrophilic

Heads

nonpolarhydrophobic

tails

polarhydrophilic

Heads

Fluid Mosaic ModelModel of the plasma

membrane

- fluid due to flexible nature of membrane

- phospholipids move like water current

- proteins in membrane create pattern

(mosaic) on membrane surface

It’s like a fluid…It’s like a mosaic…It’s the Fluid Mosaic Model!

MosaicFluid

Other ComponentsCholesterol

Helps stabilize phospholipids.Stops fatty acid chains from sticking together.

Proteins on membrane surface aid in cell identification.

Transport ProteinsSpan the width of the membraneRegulates which molecules may pass through

the membrane.

Various Functions

Outside

Plasma MembraneInside Cell

Transporter Enzyme Activity Receptor

Identity Marker Cell Adhesion Attach to Cytoskeleton