What is a polar molecule Electrons are shared

What is a polar molecule? § Electrons are shared unequally in a bond and there is a slightly + end of the molecule and a slightly – end § Nonpolar is the opposite-electrons shared equally § IN WATER-Oxygen pulls Hydrogen’s electrons closer to it § Positive end of one water molecule is attracted to negative end of another water molecule

Polar Molecules § Polar=Hydrophilic (water) § Nonpolar= hydrophobic(oil)

The Cell Membrane § § § Discovered 1972 by Singer and Nicholson Composed of phospholipids and proteins Model of membrane is FLUID MOSAIC MODEL § Phospholipids- composed of – Polar head- contains a phosphate group – Nonpolar tail- lipid portion § Looks like a clothespin

Phospholipid Bilayer § Phospholipids form a 2 layered membrane § Heads point toward outside and inside of cell- water § Tails point toward each other- don’t let water in § Keeps wrong things out, lets right things in – Many reactions take place in the non-polar region

Proteins in the Bilayer § 4 Kinds– Transport Proteins- allow passage of materials in and out of cell – Receptor Proteins –transmit info in and out by reacting with chemical signals (hormones) – Marker Proteins- “cellular name tags” – Enzymes- help reactions occur § Proteins float like icebergs in a sea of phospholipids

Membrane Proteins § Proteins are shape specific- channel, receptors, and enzymes will only fit a certain type of molecule- makes sure nothing bad gets in § Marker proteins- identify the cell as yoursnot a foreign body- i. e. Red Blood Cells (blood types)

THE CELL MEMBRANE MARKER PROTEIN CHANNEL PROTEIN