LFS100 - Lectorial 3 PDF

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LFS100 - tutorial 3...

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Lectorial 3: Plasma Membrane Structure and Function Task 2 CSi Assignment   

Assignment information video (13 minutes) Assessment/Task 2 Csi Checkpoint – Friday, week 4

Topic 2 – Things to think about      

The plasma membrane is amphipathic – hydrophobic tails and hydrophilic heads Selective permeability Movement of substances across the membrane Passive transport vs active transport Diffusion, facilitated diffusion, osmosis Bulk transport

TEST YOURSELF Q1: According to the fluid mosaic model of cell membranes, which of the following is a TRUE statement about membrane phospholipids? a. they can move laterally along the plane of the membrane Q2: What kinds of molecules pass through a cell membrane most easily? b. small and hydrophobic Q3: A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, sterile distilled water, equal to the volume of blood lost, is transferred directly into one of his veins. What will be the most probable result of this transfusion? c. the patient’s red blood cells will swell because the blood fluid is hypotonic compared to the cells

Q4: Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using the information, which transport mechanism is most probably functioning in the intestinal cells? e. facilitated diffusion Q5: An organism with a cell wall would have the most difficulty doing which process? d. phagocytosis Permeability of the Phospholipid bilayer   

i.e movement across membrane non-polar molecules – hydrophobic e.g. lipids, O2, CO2 – YES Polar molecules – hydrophilic

Small polar Uncharged molecules – YES BUT SLOW e.g. H2O, ethanol larger polar uncharged molecules – NO (e.g. glucose, amino acids and proteins) charged molecules – ions – NO REPELLED (e.g. Na+, K+, Ca2+) Match the Following pairs a. b. c. d. e. f. g. h.

Protein channel = ion transport Ligand gated ion channel = neurotransmitter Glycoprotein = cell-cell recognition Motor protein = transport of vesicles Aquaporin = osmosis Turgid (plant cell) = hypotonic environment Electrogenic pump = proton pump Exocytosis = secretion

ACTIVITIES A section of the plasma membrane has to be repaired – how is the new piece of membrane formed and inserted into the plasma membrane HINT: list the steps, make a drawing You place a cell into a beaker of: -describe what happens next [hint-make a drawing]  

Hypotonic solution (e.g. pure water) Hypertonic solution (e.g. sea water)

Bioflix videos / animations Suggested bioflix videos    

Passive transport [1.05 min] Active transport [0.50 min] Exocytosis and endocytosis [27s] Membrane transport [3.20min]...