diffusion

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Membrane diffusion

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Cell Membranes Osmosis and Diffusion:

Cell Membranes Osmosis and Diffusion MAHESH MAHENDRAKAR

Functions of Membranes:

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 MAHESH MAHENDRAKAR

PowerPoint Presentation:

Phospholipid Bilayer MAHESH MAHENDRAKAR

PowerPoint Presentation:

Fluid Mosaic Model MAHESH MAHENDRAKAR

Blood-Brain Barrier:

Blood-Brain Barrier Allows some substances into the brain, but screens out toxins and bacteria Substances allowed to cross include: water, CO 2 , Glucose, O 2 , Amino Acids, Alcohol , and antihistamines. HIV and bacterial meningitis can cross the barrier . MAHESH MAHENDRAKAR

Solutions:

Solutions 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. MAHESH MAHENDRAKAR

Methods of Transport Across Membranes:

Methods of Transport Across Membranes 1. Diffusion 2. Osmosis 3. Facilitated Diffusion 4. Active Transport MAHESH MAHENDRAKAR

Methods of Transport Across Membranes:

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 MAHESH MAHENDRAKAR

Diffusion:

Diffusion Movement of molecules from an area of high concentration to an area of low concentration. Movement from one side of a membrane to another, un-facilitated MAHESH MAHENDRAKAR

PowerPoint Presentation:

Diffusion MAHESH MAHENDRAKAR

PowerPoint Presentation:

Osmosis MAHESH MAHENDRAKAR

Tonicity is a relative term:

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. MAHESH MAHENDRAKAR

PowerPoint Presentation:

Plant and Animal Cells put into various solutions MAHESH MAHENDRAKAR

PowerPoint Presentation:

Types of Transport MAHESH MAHENDRAKAR

Today’s Lab:

Today’s Lab 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? MAHESH MAHENDRAKAR

Membrane Permeability:

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 I 3 - (triiodine ion) which is soluble. I 3 - combines with the amylose and the starch molecule turns blue-black. MAHESH MAHENDRAKAR

Test for Starch:

Test for Starch Elmhurst College Website MAHESH MAHENDRAKAR

Test for Chloride ions:

Test for Chloride ions Indicator for presence of chloride ions is silver nitrate, AgNO 3 A white precipitate, AgCl, forms if chloride is present. MAHESH MAHENDRAKAR

Test for Sulfate ions:

Test for Sulfate ions Indicator for the presence of sulfate ions is Barium chloride, BaCl Barium sulfate, BaSO 4 - forms a white precipitate BaCl + NaSO 4 ----> BaSO 4 + NaCl MAHESH MAHENDRAKAR

Living Cells:

Living Cells Beet cubes will be used to see the result of boiling and adding alcohol to a live membrane. Yeast cells are used to see effects of heat Fern gametophytes are used to see result of putting live cells in solutions of varying tonicity MAHESH MAHENDRAKAR

Osmosis:

Osmosis We will make an osmometer to see osmosis Sugar solution in a dialysis tube is used to simulate a cell membrane. Various concentrations of solute may be used around the room. MAHESH MAHENDRAKAR

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