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Transcript
Homework: Graphs & Analysis Q’s for Lab 1B Do Now: 1. New Seats! Pick a place to sit. 2. Remember back to chemistry… a) What is a mole? b) What does the unit “molarity” measure? How is it calculated? Write this in your notebook. After discussing the Do Now: Read the intro and complete Pre-Lab #1-3 on Lab 1B Homework: Graphs & Analysis Q’s for Lab 1B Goal for Today: Design and carry out an experiment to measure the rate of osmosis into model cells of varying concentrations Agenda: Pre-Lab Discussion Hypotheses Procedure Set up & start experiment 30 min. wait time – discuss & hand in Lab 1A; set up graphs & start analysis for 1B Collect results & record them on the class Excel sheet Graphs must be done by hand for this lab! Homework: Work on Prob Set 8! Do Now: Take out the Lab and be ready to discuss the results and analysis questions. Goals for Today: Analyze the results of the osmosis lab Explain how the structure of the cell membrane allows it to regulate the movement of substances into and out of the cell Results: We deleted Group 3’s data… do all the other groups’ data seem okay? What conclusion can we draw about the rate of osmosis in the 30 minute period of the expt? AQ #1: What does explain mean? AQ #3: Why % change? Other questions? Forms the boundary of the cell (act as a barrier between the cell and its environment) Selectively allows certain molecules to pass into/out of cells (selective permeability) [Also has various signaling & recognition functions, but we’ll leave those for later…] 4 Main Structural Components: Phospholipids II. Proteins III. Glycolipids & Glycoproteins – Carbohydrates IV. Cholesterol Plus the ExtraCellular Matrix I. Phospholipids Amphipathic Structure (polar on one end, nonpolar on the other end) In water: Assemble into a micelle or a lipid bilayer Phospholipid Bilayer w/ embedded protein channels (pores) Also contains various other proteins, glycoproteins, and glycolipids for various signaling and recognition functions Two main types: Peripheral – on the surface of the membrane Integral/Transmembrane – passing all the way through the membrane Function primarily as signaling/recognition molecules Ex: ABO Blood Types on Red Blood Cells How do proteins and carbs get attached to the membrane? A lipid (steroid) embedded between the phospholipid tails Function: moderates the fluidity of the membrane (the Goldilocks molecule) Protein and glycoprotein fibers outside the cell, anchored to the membrane Functions: • Connect and stabilize cells within tissues • Communicate between cells • Regulate cell activity by influencing gene expression (which genes turned on/off) EXPERIMENT: Small Molecules Passive transport – down the concentration gradient (high to low) ▪ Simple diffusion – straight through phospholipids ▪ Facilitated diffusion – through a transport protein SIMPLE DIFFUSION FACILITATED DIFFUSION What kinds of molecule would use each type of diffusion? Small Molecules Passive transport – down the concentration gradient (high to low) ▪ Simple diffusion – straight through phospholipids ▪ Facilitated diffusion – through a transport protein Active transport – requires ATP, goes from low to high conc. ▪ Ex: Na/K pump Large Molecules Endocytosis – entrance via vesicle pinching off from cell membrane ▪ Phagocytosis – cell eating (big chunks) ▪ Pinocytosis – cell drinking (water and small nutrients) Exocytosis – exiting via vesicle merging into cell membrane Turgid – Firm and sturdy due to being filled with water Turgid cells have turgor pressure – pressure of water pushing outward on cell wall Keeps plants upright when in a hypotonic environment Flaccid – Limp, un-sturdy due to lack of turgor pressure Plant cells are flaccid when in isotonic environments Think wilted plant Plasmolysis – The shrinking of the cytoplasm and plasma membrane away from the cell wall Caused by osmosis out of the cell due to a hypertonic environment Marine: not enough water, too much salt! Protozoa: Osmoconformers (cytoplasm has same solute concentration as ocean water) Fish: Drink a lot, really concentrated urine, pump salt out through gills Freshwater: too much water! (danger of cells exploding) Protozoa: Contractile vacuoles Fish: Really dilute urine Go to Ch. 7 videos on CD http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535:: /sites/dl/free/0072437316/120068/bio02.swf::Endoc ytosis%20and%20Exocytosis Paramecium (watch closely for contractile vacuole) Phagocytosis (Amoeba [green] consuming yeast cells [red])