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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Simple diffusion The term simple diffusion refers to a process whereby a substance passes through a membrane without the aid of an intermediary such as a integral membrane protein. The force that drives the substance from one side of the membrane to the other is the force of diffusion. In order for substances to pass through a cell membrane by simple diffusion it must penetrate the hydrophobic core of the phospholipid bilayer. The types of molecules that can do this are themselves substantially
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Ronald Wilson Pd:4th 11/16/12 Introduction In this experiment diffusion and osmosis is the main idea. When using diffusion and osmosis you are trying to separate different solute concentrations on either side of the membrane. Only a solute’s relative concentration‚ or water potential‚ affects the rate of osmosis. The higher the concentration of solutes‚ the faster water will flow through the membrane to equalize the concentration. The way we describe the movement from higher to lower concentration
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Diffusion and Osmosis in an egg Low concentration 1.1 Diffusion is the process of molecules spreading from areas of high concentration to areas of low concentration. High concentration 1.1 Osmosis is the diffusion of water molecules through a semi-permeable membrane from the area of low concentration of solute to the area of high concentration of solute. 1.2 Diffusion is important to living cells because it’s the way they take in materials from the environment‚ and they also prevent themselves
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OSMOSIS OF EGG MEMBRANES A laboratory report submitted for LE@D Biology 1004 Michele Liveley Arkansas State University Mountain Home Mountain Home‚ AR September 2013 Osmosis Egg Lab Report Introduction Osmosis is the passing of water or other solutions from an area of high concentration of particles to an area of less concentration. The cell membrane is an organelle‚ selectively permeable‚ and only allows certain materials to pass through; it can allow
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For this to happen‚ the molecules need to dissolve through a partially permeable. Osmosis is the diffusion of water as it goes from dilute to a more concentrated solution. Active transport is the movement of molecules from low concentration to high concentration against the concentration gradient. Energy is required for movement
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Title Membrane Permeability Aim To determine the effect of various chemicals and high temperature on the membrane permeability of beetroot Hypothesis Organic solvent and high temperature will destroy the cell membrane and make it permeable to the red pigment. The higher the concentration of the alcohol‚ the greater will be this effect. Principle Beetroot is the material used in this experiment to demonstrate the effects of high temperature and chemicals on the permeability of the cell membranes
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mosaic model of the cell membrane. What is the fluid mosaic model? The fluid mosaic model is a model conceived by S.J. Singer and Garth Nicolson in 1972 to describe the structural features of biological membranes. The membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid‚ but more like a ’fluid’. The membrane is depicted as mosaic because
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mimic a cell membrane. Two ways why this model realistically represents a cell is because the dialysis bag is semi-permeable‚ like a cell. The bag was able to allow water in‚ as the size of the water molecule was small enough to be able to fit through the pores of the bag. Sucrose was not able to pass through as the molecules were too big to enter. This is similar to a cell because the size of a molecule can determine whether or not the substance can enter the cell through diffusion. Larger molecules
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Introduction The reason of this experiment was to identify the properties and effects of osmosis. Osmosis can be defined as the diffusion of water through a selectively permeable membrane. (Miller/Levine) Osmosis occurs when there is an area of higher and lower concentration. Osmosis is a type of diffusion. Diffusion is when molecules move from an area of higher concentration to an area of higher concentration. The three types of concentrations are hypotonic‚ hypertonic‚ and isotonic. When in comparison
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