4.1 Aim The aim of this lab session is to demonstrate the effect of different conditions on membrane permeability. 4.2 Learning Objectives In this Lab Session‚ students will acquire the skills to: - analyze the effect of different temperatures on membrane integrity. - analyze the effect of the organic solvent acetone on membrane integrity. 4.3 Introduction Even though membranes separate cells from their surrounding environment and different organelles within the cells from the
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the smallest unit of life‚ is surrounded by a plasma membrane. The plasma membrane functions somewhat like a wall‚ as it keeps the internal contents from the external environment. Just like a wall‚ the membrane is also somewhat permeable‚ except that the membrane takes a much more active role in determining what is allowed in to the cell and what is kept out. The plasma membrane is a very thin structure‚ which has some very important tasks. One of the main tasks that it performs is to control the
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1 Experiment Membrane Transport Objectives ► Referring to energy‚ what two ways can substances enter a cell? What is active transport? What is passive transport? How is osmosis related to diffusion? How can we demonstrate active transport? How can we demonstrate Brownian movement? How can we demonstrate diffusion (2 ways)? How can we demonstrate osmosis (3 ways)? In terms of relationships between substances‚ how can we define “hypertonic”‚ “isotonic”‚ and “hypotonic”? What is the relationship
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substances across a semipermeable membrane to gain a better understanding of how cells move materials across cell membranes. The experiment was designed to exhibit Brownian Motion; the random movement and tendency of particles of a substance to move from an area of greater concentration to lower concentration via diffusion until equilibrium has been attained. In addition to observing the passive process of diffusion‚ the experiment demonstrated how a semipermeable membrane will only allow certain substances
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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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The Lipid Barrier of the Cell Membrane‚ and Cell Membrane Transport Proteins The structure of the membrane covering the outside of every cell of the body is discussed in Chapter 2 and illustrated in Figures 2–3 and 4–2.This membrane consists almost entirely of a lipid bilayer‚ but it also contains large numbers of protein molecules in the lipid‚ many of which penetrate all the way through the membrane‚ as shown in Figure 4–2. The lipid bilayer is not miscible with either the extracellular
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K+ channels than cell B‚ which cell has the larger resting membrane potential? Explain. If the permeability to K is higher in A than in B‚ then the resting membrane potential (rmp) will be closer to the equilibrium potential in cell A‚ which means the rmp will be more negative in cell A than in cell B; or in other words‚ the potential difference will be LARGER in cell A. 2. Predict the effect of a reduced extracellular concentration of Na+ on the magnitude of the action potential in an electrically
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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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and concentration gradients Bradley Benton ABSTRACT In this experiment‚ we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane. INTRODUCTION A major determinant of diffusion in a biological system is membrane permeability
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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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