CAS BI 315 Chapter Notes - Chapter 2: Hemolysis, Chemical Polarity, Facilitated Diffusion
1 Jul 2018
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Lab 2: Water and Solute Movement through Cell Membranes
I. Three fluid compartments → plasma, interstitial, intracellular
II. Transport across a Membrane
A. Simple Diffusion: small and large nonpolar molecules down their concentration
gradients
B. Simple Diffusion through Protein Channels: ions and some small polar molecules
down their concentration gradient via holes created in the membrane
C. Protein-Mediated Transport: ions and some large polar molecule down
(facilitated diffusion) or against (active transport) ccn gradient
III. Rate of diffusion for uncharged, polar mlc → dependent on lipid solubility and ability to
form hydrogen bonds
IV. Two types of solutes:
A. Non-penetrating: don’t diffuse through the cell membrane (ex. NaCl)
B. Penetrating: readily diffuse through the membrane b/c of lipid solubility; cross
membrane with assistance from protein molecules in membrane (ex. Urea
through aquaporins and glucose)
V. Solute Particle Things
A. Osmolarity: solute particles → penetrating and non-penetrating (hyper-, iso-,
hypo-)
A.1. Hyperosmotic - more solutes particles
A.1.a) Penetrating - solute moves into cell and water follows =
cell swells
A.2. Depends on 3 factors
A.2.a) Polarity
A.2.b) Size
A.2.c) mechanism
B. Tonicity: measure of osmotic pressure caused by non-penetrating solute particles
(hyper-, iso-, hypo-)
B.1. Hypertonic - more nonpenetrating
B.1.a) Water moves out of cell = cell shrivels
B.2. Unlike osmolarity, tonicity is only influenced y solutes that cannot
cross the membrane
B.3. Takes into account dissociation: NaCl is two! Glucose is 1
C. Think about how a cell in non iso- environment is affected → swelling, shrinking
C.1. A hyperosmotic and hypertonic soln of NaCl will cause shrinking,
as water will be drawn out of the cell to the nonpenetrating solutes
C.2. A hyperosmotic soln of a penetrating solute plus an isotonic soln
of NaCl will have no effect -> water that follows the penetrating solute into
the cell will make the NaCl solution hypertonic, so water will be drawn out
again to create no net effect on H2O movement
D. RBC → shrink = crenate; RBC → burst = hemolysis
E. Hemolysis → fragments will settle at bottom of tube → transparent → we can see
the lines
F. Turbidity → how cloudy a solution is (low turbidity = relatively clear)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Lab 2: water and solute movement through cell membranes. Rate of diffusion for uncharged, polar mlc dependent on lipid solubility and ability to form hydrogen bonds. Two types of solutes: non-penetrating: don"t diffuse through the cell membrane (ex. Nacl: penetrating: readily diffuse through the membrane b/c of lipid solubility; cross membrane with assistance from protein molecules in membrane (ex. Solute particle things: osmolarity: solute particles penetrating and non-penetrating (hyper-, iso-, hypo-) Penetrating - solute moves into cell and water follows = Size mechanism: tonicity: measure of osmotic pressure caused by non-penetrating solute particles (hyper-, iso-, hypo-) Water moves out of cell = cell shrivels. Unlike osmolarity, tonicity is only influenced y solutes that cannot cross the membrane. Glucose is 1: think about how a cell in non iso- environment is affected swelling, shrinking. A hyperosmotic and hypertonic soln of nacl will cause shrinking, C. 1. as water will be drawn out of the cell to the nonpenetrating solutes.
