MEMBRANE ACTIVITY

Membranes are made of LIPIDS!!!

Membranes are made of PHOSPHOLIPIDS Head Phosphate Group HYDROPHILIC (attracted to water) Tail 2 Fatty Acids Instead of 3 Hydrophobic (not attracted to water)

Phospholipid Bilayer Model

MEMBRANE REVIEW!!! WHAT ARE MEMBRANES COMPOSED OF?? DRAW ME A PHOSPHOLIPID AND TELL ME ABOUT ITS 2 MAIN PARTS. HOW ARE PHOSPHOLIPIDS ARRANGED IN A MEMBRANE, AND WHY? WHAT ACTS AS “DOORS” TO THE MEMBRANE, ALLOWING THINGS IN AND OUT?

MEMBRANE PROTEINS What Do They Do? Membrane proteins provide ways for the cell to let things in, and to let things out. It has different ways to regulate what can pass through, and when. How Do They Do It?

HOW DO WE DO IT? TRANSPORT CHANNELS ENZYME ACTIVITY Let Molecules of a Certain Size or Shape Pass Into The Cell ENZYME ACTIVITY Enzymes in the Membrane Help With Important Chemical Reactions

Proteins on the Outside of Cells Recognize Each Other HOW DO WE DO IT? CELL-TO-CELL RECOGNITION Proteins on the Outside of Cells Recognize Each Other CELL SIGNALING Chemicals Cause Protein To Change Shape and Signal a Message For The Cell To Do Something

DIFFUSION When Molecules Move From An Area Of High Concentration To An Area Of Low Concentration Through A Medium

Diffusion Can Also Occur Through A Semi-Permeable Membrane Zombie-Diffusion. It Exists. Be Prepared.

DIFFUSION Some Membranes Are Selectively Permeable. This Means They Are Designed To Only Let Molecules Of A Certain Size or Shape Through.

DIFFUSION Passive Transport Allows For Molecules to Pass Freely. Active Transport Requires Energy For The Molecules To Pass. When Passive Transport Happens As A Part Of Diffusion, It Is Called “Facilitated Diffusion”

OSMOSIS The Passive Transport Of Water Through A Selectively Permeable Membrane Sometimes, instead of chemical molecules moving from areas of high concentration to low (like in Diffusion) the WATER moves instead, because the molecules are too big to pass through the membrane.

OSMOSIS It’s All About Balance and Equilibrium In an ISOTONIC solution, the water flow in and out of the cell is EQUAL. There is a BALANCE. In a HYPOTONIC solution, the water moves INTO the cell. In a HYPERTONIC solution, water moves OUT of the cell.

VESICLES Cells Can Create Membranes To Take Things Into and Send Things Out Of The Cell In EXOCYTOSIS, membranes are used to transport things OUT of a cell. In ENDOCYTOSIS, membranes are used to bring things INTO a cell.