Warm Up – 11/11 Compare simple diffusion and facilitated diffusion. Similarities and differences! List two characteristics of molecules that can move across cell membranes through simple diffusion. When do molecules stop moving on the concentration gradient? Sketch the cell membrane – Include: phospholipid, transport proteins, lipid bilayer, head, and tail

Cell Membrane The cell membrane is Selectively Permeable Made of double-layer of Phospholipids. Named the phospholipid bilayer. Strong and flexible barrier The cell membrane is Selectively Permeable Some substances can cross the membrane easily, while others cannot!

The Properties of Lipids Phospholipid Review Fatty acid portions of such a lipid are hydrophobic, or “water-hating” The opposite end of the molecule is hydrophilic, or “water-loving.”

The Properties of Lipids The hydrophobic fatty acid “tails” cluster together The hydrophilic “heads” are attracted to water inside and outside of the cell. A lipid bilayer is the result.

The Fluid Mosaic Model There are also carbohydrates and proteins embedded in the membrane. The membrane contains several different molecules, but remains flexible (Like a liquid)

Cellular Transport

Cell Membrane Structure Phospholipid Bilayer Proteins: Embedded in between the phospholipids Fluid Mosaic Model Phospholipid Protein Phospholipid Bilayer Phospholipid Polar Head Fatty Acid Chains Slide 3.7a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Plasma Membrane Functions Maintains boundaries Controls what enters and leaves the cell Figure 3.2 Slide 3.7b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The cell membrane is selectively permeable Some materials are able to…. Move in and out of the cell freely Pass through at certain times Others cannot pass through the membrane.

List two characteristics that can prevent molecules from passing through the cell membrane.

Size – Size limits a molecules ability to pass through the membrane Charge – Charged molecules have a hard time passing in between the nonpolar tails.

Predict the results What do you predict will happen if food coloring is dropped into a beaker of water?

There are Two Types of Cellular Transport Passive Transport & Active Transport

There are three forms of passive transport. a. Passive Transport -Molecules move from a high concentration to a low concentration. -No energy is required There are three forms of passive transport. A. Simple Diffusion B. Facilitated Diffusion C. Osmosis

Types of Passive Transport A. Simple Diffusion Types of Passive Transport Molecules move across the cell membrane through the phospholipids Direction of flow: high concentration to low concentration No energy is required Examples: Carbon Dioxide & Oxygen

B. Facilitated Diffusion The diffusion of larger or charged molecules through a protein molecule Molecules move from a high concentration to low concentration No energy is required Glucose is an example of a molecule that moves by facilitated diffusion

C. Osmosis No energy is required Osmosis is the facilitated diffusion of water molecules across a selectively permeable membrane. Direction of Movement is from a high concentration to low concentration No energy is required The diffusion of water molecules is OSMOSIS.

Aquaporin!! Water molecules

Osmosis What effect would osmosis have on a cell if water rushed into it? What if water rushed out of it?

Osmosis Three possible effects of osmosis on cells Isotonic: amount of solutes is equal inside and outside of the cell. Hypertonic: higher amount of solutes outside of the cell. Hypotonic: lower amount of solutes

Osmosis Hypertonic Hypotonic Isotonic Always refers to the concentration of solutes outside of the cell!!!

DIFFUSION OCCURS THROUGH THE CELL MEMBRANE OF CELLS!!!!! The movement of molecules from a high concentration to a low concentration DOES DIFFUSION REQUIRE ENERGY? Diffusion does NOT require energy DIFFUSION OCCURS THROUGH THE CELL MEMBRANE OF CELLS!!!!!

HOW IS DIFFUSION IMPORTANT FOR YOUR SURVIVAL? Cellular Transport!!! Materials move across cell membranes (into or out of cells) Materials can be used by the cell or transported by the cell throughout the organism. What types of materials do cells transport through out your body? Water, Oxygen, Carbon Dioxide, Glucose, etc

ACTIVE TRANSPORT

Types of Active Transport include: Protein Pumps Endocytosis Movement of molecules into or out of cells from low concentration to high concentration Requires energy to occur (ATP). Types of Active Transport include: Protein Pumps Endocytosis Exocytosis

The bonds between the ATP parts are broken A-P-P P Active Transport Requires Energy (ATP) ATP (adenosine triphosphate) is a molecule that contains energy in its bonds A-P-P~P The bonds between the ATP parts are broken A-P-P P Energy within the bond is released and used by our cells for active transport A-P-P P (energy released)

Protein Pumps: a specialized protein pumps a substance across the membrane Movement is from low concentration to high concentration Requires energy (ATP) The sodium/potassium pump is an example (needed to send impulses along nerve cells) Sodium-Potassium Pump - Video

Endocytosis Taking materials into the cell with a vesicle. Movement is from low to high concentration Energy is required to surround materials with in a vesicle Examples of Endocytosis: Phagocytosis brings solids into the cell (WBC engulfing disease causing bacteria) Pinocytosis brings liquids into the cell

Endocytosis

Exocytosis Exporting large materials out of a cell using a vesicle. The movement is from low to high concentration Cells use energy to transport material in vesicles. Example: A cell releasing indigestible material

Exocytosis