Types of Transport Across Cell Membranes

Simple Diffusion Brownian Movement Requires NO energy, passive movement Molecules move from area of HIGH to LOW concentration Random movement of particles Brownian Movement

Diffusion of Liquids

Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW)

Diffusion across a membrane Semipermeable membrane Osmosis Diffusion of WATER across a membrane Moves from HIGH water concentration to LOW water concentration Diffusion across a membrane Semipermeable membrane

Three types of conditions Isotonic solutions When the amount of solutes is equal inside and outside of cell (cell will stay the same) Hypotonic solution When solutes outside are lower than inside cell (cell will swell) * more water outside Hypertonic solution When solutes outside are higher than inside cell (cell will shrink) * more water inside cell

Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________.

Cell in Hypotonic Solution 10% NaCL 90% H2O CELL H2O 20% NaCL 80% H2O What is the direction of water movement?

Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL H2O 5% NaCL 95% H2O What is the direction of water movement?

Cells in Solutions

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS

Osmosis in Red Blood Cells Isotonic Hypertonic Hypotonic

Hypertonic Isotonic Hypotonic Hypertonic Isotonic Hypotonic

Moving Things in and out of Cells Cellular Transport

A.Passive Transport (2 types) 1.Simple Diffusion Doesn’t require energy Moves high to low concentration (Down) Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.

2. Facilitated diffusion Doesn’t require energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell.

2.Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins.

2.Facilitated Diffusion Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side.

B.Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST (up) concentration gradient

Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

Large molecules move materials into the cell by. 1. Endocytosis Moving the “Big Stuff” Large molecules move materials into the cell by.

Endocytosis Cell forms an invagination Materials dissolve in water to be brought into cell Called “Cell Drinking”

2. Exocytosis The opposite of endocytosis is exocytosis 2.Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released out of the cell through the cell membrane. Inside Cell Cell environment

Exocytosis