September 11, 2012

Standard: SAP1d-Relate cellular metabolism and transport to homeostasis and cellular reproduction.Warm-Up:Complete ARG 5.1 located on your desk. Read the paragraphs and answer the questions. Write the answers only in your composition notebooks.

Cell Physiology:Membrane Transport

Membrane Transport• Intracellular fluid – inside the cell

• Interstitial fluid – outside the cell; contains nutrition for the cell (amino acids, sugar, fatty acids, vitamins)

• A healthy cell must be able to extract what it needs from the interstitial fluid.

Passive Transport Mechanisms(require no energy)

A. Diffusion- solutes1. Molecules move from

concentrations

2. Substances move down their concentration gradient

3. Solutes -must be lipid-soluble or small.

4. O and CO2 move across the cell membrane through diffusion

B. Osmosis - diffusion of water through a selectively permeable membrane

Hypertonic Solution

• Solute + solvent =solution• Hyper (solute) =“high”

concentration of solutes in the solution

• More solutes less water (solvent)

• Water moves out and cell shrinks

Hypotonic Solution

• Hypo (solute) =“low” concentration of solutes in the solution

• Less solutes more water (solvent)

• Water moves in and cell swells

Isotonic Solution

• Solutes in cell = solutes outside the cell

• Water moves in and out at the same rate (no net movement)

• A healthy cell

Facilitated Diffusion

C.• Passive movement

using a protein carrier molecule

• Glucose moves across the cell membrane this way.

D. Filtration1. Pressure is necessary to force (blood)

substances through membrane.2. Important in the capillaries and also the

kidneys.

Active Transport MechanismsRequire Energy (ATP)

Three conditions where active transport is necessary:

1. Molecules are too large to pass through

2. Molecules are not lipid soluble

3. Molecules are moving against the concentration gradient

Solute Pumping (Na+/K+ Pump)

Substances move with protein carrier molecules (solute pumps) against the

gradient.

Ex. Amino acids are transported this way

Bulk TransportExocytosis- “out of cell”

• Cell products, hormones, and wastes in vesicle fuses with cell membrane.

• Fused area ruptures, spilling contents of sac outside of cell.

Endocytosis

• Endo= “into”

• Extracellular components are engulfed, a vesicle is formed, it detaches itself from the membrane and moves into cytoplasm.

Two types of Endocytosis:

• 1. Phagocytosis –”cellular eating” uptake of solid particles

• 2. Pinocytosis – “cellular drinking” uptake of fluids