Youtor
Osmosis amp Diffusion
>> YOUR LINK HERE: ___ http://youtube.com/watch?v=Bz2cseDaLes
Osmosis Diffusion • Visit our website: http://www.sliderbase.com/ • Free PowerPoint Presentations for teaching and learning • Functions of Membranes • 1. Protect cell • 2. Control incoming and outgoing substances • 3. Maintain ion concentrations of various substances • 4. Selectively permeable - allows some molecules in, others are kept out • Allows some substances into the brain, but screens out toxins and bacteria • Substances allowed to cross include: • water, CO2, Glucose, O2, Amino Acids, Alcohol, and antihistamines. HIV and bacterial meningitis can cross the barrier. • Solutions are made of solute and a solvent • Solvent - the liquid into which the solute is poured and dissolved. We will use water as our solvent today. • Solute - substance that is dissolved or put into the solvent. Salt and sucrose are solutes. • Tonicity is a relative term • Hypotonic Solution - One solution has a lower concentration of solute than another. • Hypertonic Solution - one solution has a higher concentration of solute than another. • Isotonic Solution - both solutions have same concentrations of solute. • We are using dialysis tubing as the cell membrane - It is selectively permeable • The solute is either the eosin starch solution or the sugar solution • What is the solvent? • Membrane Permeability • Solute is eosin-starch-chloride solution • Solvent is Water • Indicator for presence of starch is IKI • Starch is made of amylose and amylopectin – amylopectin is insoluble • Iodine is not very soluble in water, but with KI it forms a I3- (triiodine ion) which is soluble. • I3- combines with the amylose and the starch molecule turns blue-black.
#############################
