What is the difference between active and passive transport? contrapositive-(con tra ‘pa ze tiv)- (noun)- a proposition or theorem formed by contradicting both the hypothesis and conclusion of a given theorem and interchanging them. Oddly enough, the contrapositive of a statement is equivalent to the original statement. For example, “If a student says ‘hi’ to Mr. Cahall, then he will high-five them” is equivalent to its contrapositive, “If Mr. Cahall doesn’t high-five a student, then they didn’t say hi to him.”

Solutions Molecules dissolved in a liquid = SOLUTES Liquid/fluid dissolving them = SOLVENT This makes a SOLUTION In a salt solution, ______________ is the solute and _____________ is the solvent In a sugar solution, sugar is the solute and water is the solvent. SALT WATER

Concentration and Equilibrium Solutions will spread out their dissolved molecules until they are equal throughout. The number of molecules in a certain are per unit volume is called the CONCENTRATION. High concentration: more solutes per unit volume Low concentration: less solutes  per unit volume

If the solutions on either side of the barrier have the same concentration we call that being at equilibrium. At equilibrium, both the solvent and solute move back and forth across the barrier: there is always movement.

Passive Transport The movement of materials across a membrane without using energy There are three different types: 1. Diffusion – the process in which solutes move across a membrane from areas of high concentration (crowded) to areas of low concentration

Passive Transport 2. Facilitated Diffusion – molecules are moved across a cell membrane with the help of a protein because they are either too large or have a charge and can’t pass through the membrane How? The proteins form a channel like a large hold in the membrane, this doesn’t require any energy and the molecules move through the passage.

Passive Transport 3. Osmosis– the movement of water across a membrane. The water molecules are trying to reach equilibrium. Water is small so it can move quickly, much faster than larger molecules. It will move to the area of higher solute concentration to help dilute it.

Gradients When there is a difference in solution concentrations we say that there is a gradient.

ACTIVE Transport!! Movement across a cell membrane that requires energy because it is AGAINST the concentration gradient (it moves solutes from low to high—where it’s already crowded) There are three different types: 1. Pump – a special type of protein is used to PUSH molecules to an area of high concentration. This requires ENERGY! An example is a Sodium and Potassium Pump. It uses ATP as energy! This creates a gradient which the cell can use to send messages to other cells.

Large Particle Transport!! 1. Endocytosis (Endo=in) – a pocket (vesicle) forms around outside material and buds inward to release the material indie the cell. The vesicles are organelles called vacuoles.

Large Particle Transport!! 2. Exocytosis (Exo=out) – a vesicle inside the cell fuses with the cell membrane and releases its contents outside the cell.

Isotonic Solutions Solute concentration is equal on inside and outside of cell Water moves in both directions No NET movement

Hypotonic Solutions A higher solute concentration inside the cell than outside  water flows into cell This can cause a cell to burst

Hypertonic Solutions More solute concentration outside of the cell than inside  water flows out of cell This can cause cell to shrink

Hypertonic http://www.youtube.com/watch?feature=player_embedded&v=IRQLRO3dIp8

Predict what will happen….

Water leaves the cell and it shrivels or shrinks 1. Water leaves the cell and it shrivels or shrinks Cell _______________________   Environment _____________________ hypotonic hypertonic

Water enters the cell and it swells 2. Water enters the cell and it swells Cell_________________________   Environment _____________________ hypertonic hypotonic

Water leaves the cell and it shrivels or shrinks 3. Water leaves the cell and it shrivels or shrinks Cell_________________________   Environment _____________________ hypotonic hypertonic

Equal water entering and leaving cell so cell is in homeostasis 4. Equal water entering and leaving cell so cell is in homeostasis Cell_________________________   Environment _____________________ isotonic isotonic