Section 1 cont. Turgor pressure- the pressure that water molecules exert against the cell wall Do the cells of this plant have turgor pressure?

Plasymolysis- when a plant doesn’t receive enough water and the cell membrane shrinks from the cell wall; turgor pressure is not maintained Plasymolysis- when a plant doesn’t receive enough water and the cell membrane shrinks from the cell wall; turgor pressure is not maintained

Facilitated Diffusion A type of passive transport that is used for A type of passive transport that is used for 1) molecules too large to pass through 1) molecules too large to pass through the cell membrane the cell membrane 2) molecules that do not dissolve in lipids 2) molecules that do not dissolve in lipids

Facilitated diffusion uses a carrier protein.

Facilitated Diffusion 1. Molecule attaches to protein. 2. Protein changes shape. 3. Molecule is released to other side. 4. Protein returns to original shape. What might this molecule be?

Ion Channels Membrane proteins move Na+, K+, Ca +2, Cl- across the cell membrane Membrane proteins move Na+, K+, Ca +2, Cl- across the cell membrane

Three kinds of stimuli determine whether “gates” are open: 1) stretching of the cell membrane 1) stretching of the cell membrane 2) electrical signals 2) electrical signals 3) chemical signals 3) chemical signals

Section 2: Active Transport -requires energy -moves materials up the concentration gradient (from low to high concentration)

The Sodium-Potassium Pump The Sodium-Potassium Pump Moves 3 sodium (Na) out and 2 potassium (K) in… Moves 3 sodium (Na) out and 2 potassium (K) in…

Since there’s already more sodium on the outside, energy is required… It’s like bailing water out of a boat that continues to fill

The sodium- potassium pump moves 3 positive ions out for every 2 positive ions in; which side of the cell membrane is slightly more negative than the other?? Hmmm…

The inside… The inside of a cell (like a nerve cell) is slightly more negative than the outside The inside of a cell (like a nerve cell) is slightly more negative than the outside This electrical gradient (difference in charges) enables impulses to be sent along nerve cells This electrical gradient (difference in charges) enables impulses to be sent along nerve cells

Movement in Vesicles Endocytosis Two types: Two types: A. pinocytosis- a cell takes in fluids or solutes A. pinocytosis- a cell takes in fluids or solutes B. phagocytosis- a cell takes in large particles or whole cells B. phagocytosis- a cell takes in large particles or whole cells Exocytosis A process by which a substance is released from a cell A process by which a substance is released from a cell - toxins - toxins -proteins -proteins -waste products -waste products

Endocytosis A color-enhanced transmission electron micrograph of an amoeba engulfing green algal cell for food.

An amoeba and endocytosis… Many unicellular organisms feed by phagocytosis…

Phagocytes -Your white blood cells ingest bacteria and viruses

Exocytosis