The key organelle involved with cell transport is

§The key organelle involved with cell transport is the “CELL MEMBRANE”

Cell membranes are made of PHOSPHOLIPIDs HYDROPHILIC heads (water liking) -Attracted to the water Ø called POLAR Ø HYDROPHOBIC tails (water fearing) -Not attracted to the water Ø called NON-POLAR Ø

Types of Cellular Transport § Passive Transport § Active Transport

PASSIVE TRANSPORT § § § cell uses no energy molecules move randomly Molecules spread out from an area of high concentration to an area of low concentration. § (High Low)

Passive Transport cell doesn’t use energy 1. 2. 3. Diffusion Facilitated Diffusion Osmosis Weeee!!! high low

This is gonna be hard work!! Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis high low

1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration. 2. Diffusion continues until all molecules are evenly spaced (equilibrium is reached)

Diffusion through a membrane Cell membrane Inside cell Outside cell

Diffusion through a membrane Cell membrane Diffusion Inside cell Outside cell

What determines the rate of diffusion?

1. concentration gradient. Larger the concentration difference between the two sides of the membrane the faster the rate of diffusion. 2. Temperature. Higher temperatures give molecules or ions more kinetic energy. Molecules move around faster, so diffusion is faster.

3. The surface area. The greater the surface area the faster the diffusion can take place. This is because the more molecules or ions can cross the membrane at any one moment. 4. The type of molecule or ion diffusing. Large molecules need more energy to get them to move so they tend to diffuse more slowly. Non-polar molecules diffuse more easily than polar molecules

SIMPLE DIFFUSION

Diffusion through protein channels § SELECTIVE PERMEABILITY § GATING MECHANISM IN PROTEIN CHANNELS Voltage gated channels Ligand gated channels

Facilitated Diffusion of specific particles through transport proteins found in the membrane a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane b. Transports larger molecules

Facilitated Diffusion Glucose molecules Cellular Transport From a. High Concentration High Cell Membrane Low Concentration Through a Transport Protein channel Low

Facilitated Diffusion through a membrane Cell membrane Protein channel Inside cell Outside cell

Facilitated Diffusion through a membrane Cell membrane diffusion Protein channel Inside cell Outside cell

Facilitated Diffusion through a membrane Cell membrane diffusion Protein channel Inside cell Outside cell EQUILIBRIUM

A Diffusion (Protein Channel) B Diffusion (Lipid Bilayer) Facilitated diffusion Carrier Protein

Osmosis ‘The diffusion of water from an area of high concentration of water molecules to an area of low concentration of water across a partially permeable membrane. ’

Osmosis DILUTE SOLUTION Sugar molecule CONCENTRATED SOLUTION Cell membrane partially permeable. VERY Low conc. of water molecules. VERY High conc. Inside cell of water molecules. Outside cell

Osmosis Cell membrane partially permeable. Low conc. of water molecules. OSMOSIS High conc. of water molecules. Inside cell Outside cell