Cell Membrane and Transportation …because cellular teleportation isn’t real

0:00 min – 4:35 min

Function/Purpose 1) Controls what goes in/out of the cell (is semipermeable or selectively permeable) 2) Also acts a barrier to keep the internal metabolism/reactions separate from the outside

Structure Cell membrane is made of phospholipids Has 2 layers so it is referred to as a phospholipid bilayer

Structure Phospholipids have a polar/hydrophilic head and nonpolar/ hydrophobic tail. This causes the double membrane to have a hydrophobic environment on the inside and hydrophilic surfaces on both sides outside

Structure Proteins are scattered throughout the cell membrane, there are 2 types: Peripheral: proteins that only attach to one side of the membrane and do not go all the way across Integral: proteins that span from one side of the membrane to the other

Fluid Mosaic Model The Fluid Mosaic Model states that the cell membrane is like an ocean of phospholipids and proteins, they are able to move around freely

4:35 – 5:05

Transportation The integral proteins in the cell membrane transport things into and out of the cell in two different ways based on the concentration gradient. Molecules will naturally travel from where there is a high amount to where there is a low amount

Passive Transport Molecules move from High Concentration to Low Concentration Since molecules naturally go from where there is more to where there is less, this does NOT require energy (ATP)

Types of Passive Transport Diffusion – molecules travel down the concentration gradient through the cell membrane (like O2 and CO2) The rate of diffusion can be affected by: temperature agitation (mixing/stirring) particle size concentration difference pressure

Types of Passive Transport Facilitated Diffusion – molecules go down the concentration gradient using transport proteins Channel Proteins – tunnels that molecules can pass through Carrier Proteins – proteins open and close to transport molecules

Types of Passive Transport Osmosis – water moves across the cell membrane, very important to maintain homeostasis The water moves to dilute the side with a higher concentration of particles

Passive Transport All passive transport tries to achieve dynamic equilibrium (when the molecule to solution ratio is equal on both side) 1 molecule per ounce 3 molecules per ounce 2 molecules per ounce 2 molecules per ounce

5:05 – 11:15

Active Transport Molecules move from Low Concentration to High Concentration ATP ATP Since molecules naturally go from where there is more to where there is less, forcing them to do the opposite requires energy (ATP)

Types of Active Transport Protein Pump – Protein that uses energy (ATP) to transport molecules against their concentration gradient Example: Na+/K+ Pump out in

Types of Active Transport 2. Bulk Transport using vesicles 2a. Endocytosis – Cell takes in molecules by making a membrane bubble around it I) Phagocytosis – cell eating II) Pinocytosis – cell drinking

Types of Active Transport 2b. Exocytosis – Cell gets rid of molecules by fusing a membrane bubble to the cell membrane