BIO131_ diffusion_4f8fff4f17ebecfedef2f4a6e8c50f93.pdf

BIO 131 LAB DIFFUSION AND OSMOSIS Sameh Sarray, PhD Department of Medical Biochemistry 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...

BIO 131 LAB DIFFUSION AND OSMOSIS Sameh Sarray, PhD Department of Medical Biochemistry 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 Methods of Transport Across Membranes 1. Diffusion -passive transport (no energy expended) 2. Osmosis - Passive transport of water across membrane 3. Facilitated Diffusion - Use of proteins to carry polar molecules or ions across 4. Active Transport- requires energy to transport molecules against a concentration gradient – energy is in the form of ATP Diffusion Movement of solute from higher to lower concentration Diffusion ■ Movement of solute molecules from an area of high concentration to an area of low concentration. ■ un-facilitated and is passive (requires no energy) ■ Solute molecules move across the semipermeable membrane until equilibrium is established Osmosis Diffusion of solvent (water) through membrane following its gradient From higher (H2O) gradient (hypotonic) to lower (H2O) gradient (hypertonic) Osmosis ■ Movement of water molecules following its concentration gradient, from an area of high concentration (hypotonic solution) to an area of low concentration (hypertonic concentration). ■ Movement from one side of a membrane to another, un-facilitated and is passive (requires no energy) ■ water molecules move across the semipermeable membrane until equilibrium is established Tonicity is a relative term ■ Hypotonic Solution - One solution has a lower concentration of solute than another (in other words there is higher water gradient) ■ Hypertonic Solution - one solution has a higher concentration of solute than another. (in other words there is lower water gradient) ■ Isotonic Solution - both solutions have same concentrations of solute. Plant and Animal Cells put into various solutions END Uses of Diffusion & osmosis - Dialysis removes the waste products and extra fluid from your blood by filtering them through a membrane similar to the way healthy kidneys would. During dialysis, blood is on one side of the membrane/filter and a special fluid called dialysate (containing water, electrolytes, and minerals) is on the other. Small waste products, toxins in your blood flow through the membrane/filter by diffusion and into the dialysate