Topic 2 – Cell membranes Reading Chapter 5 Objectives Functions of cell membranes The fluid mosaic model The lipid bilayer – phospholipids‚ glycolipids and sterols Properties of the lipid bilayer Membrane proteins – the ‘mosaic’ in the model Solute movements across membranes BIO 1140 – SLIDE 1 http://www.nikonsmallworld.com/gallery/year/2006/id/751 Functions of cell membranes – an overview Fluid mosaic model Singer & Nicolson 1972 Fluid lipid molecules in which
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Membrane Transport Process Process Energy Source Description Examples Passive processes Simple diffusion Kinetic energy Kinetic energy Net movement of particles (ions. molecules. etc.) from an area of their higher concentration to an area of their lower concentration. that is. along their concentration gradient Movement of fats‚ oxygen‚ carbon dioxide through the lipid portion of the membrane‚ and ions through protein channels under certain conditions Osmosis Kinetic energy Simple diffusion
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solution‚ 15% glucose/1% starch solution‚ distilled water‚ balance‚ sucrose solutions (0.2M‚ 0.4M‚ 0.6M‚ 0.8M‚ 1.0M)‚ glucose test tape‚ beakers (multiple)‚ petri dish. In the experiment‚ one will measure diffusion through a selectively permeable membrane (dialysis tubing). A 30 cm by 2.5 cm piece of dialysis tubing that has been soaked in water is acquired and made into a bag by tying one end of the dialysis tubing and opening the other end. Next‚ place 15 mL of the 15% glucose/1% starch solution
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ratio will experience the greatest weight change‚ because more water can move by osmosis across the potato cell’s semi permeable membrane. 2) If potato pieces are immersed in various salt solutions‚ then the pieces immersed in the most concentrated solution will experience he greatest weight change‚ because more water must pass across the potato cells semi permeable membrane by osmosis to achieve an equilibrium. The results from testing these hypotheses did not support either and were shown to be flawed
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Experiment 2 The Cell Membrane Abstract The boundary between any cell and its environment is the plasma membrane‚ composed of a matrix of phospholipid molecules along with a number of different kinds of proteins. Membranes have different properties and a variety of functions‚ in large part determined by the specific proteins within the membrane. This experiment is designed to determine the stress that various factors‚ such as osmotic balance‚ detergents and pH‚ have on biological membranes. There are three
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Diffusion and osmosis are very important in biological process. Diffusion is the movement of molecules or ions from a region of their high concentration to a region of their low concentration. Osmosis is the diffusion of water molecules across a semipermeable membrane. To gain a better understanding of diffusion and osmosis‚ we examine multiple experiments to show diffusion and osmosis in animal cell‚ plant cell and synthetic cell. In our first experiment‚ we weight a decalcified chicken egg and place 10%
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Cell Membrane Structure Phospholipids are arranged in to layers‚ called the bilayer. They only have 2 fatty acids‚ this is because the third fatty acid is replaced by a negatively charged phosphate group. The phosphate heads are polar‚ in other words attracted to water‚ therefore they are hydrophilic. The lipid tails are non-popular as they’re not attracted to water and therefore known as hydrophobic. When phospholipids are added to the water‚ they rearrange themselves so that the hydrophilic heads
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Experiment 2 : Transport Across Membrane Name : Matrix No : Group : B Semester : 1 Date of Experiment : 05.09.2013 Lecturer’s Name : Miss OBJECTIVE To study the effects of hypotonic‚ hypertonic and isotonic solutions on plant and animal cells. INTRODUCTION In cellular biology the term membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes‚ which are lipid bilayers that
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process of the facilitated diffusion of glucose through a selectively permeable membrane. Introduction: Experiment #1 and #2 are meant to show the processes of Simple and Facilitated diffusion. Both the solutes and water were used to show how they diffuse through a semi permeable membrane. In experiment #1 the process of using the solute and deionized water shows how much of the solute is passed through the membrane. In experiment #2 the rate of facilitated diffusion relied on the amount of carrier
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food colouring or ink into a clear glass of water. Water will let other molecules move among the water molecules so freely that the water carries or transports them. The diffusion of particles into and out of cells is regulated by the plasma membrane‚ which constitutes a physical barrier. In general‚
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