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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Biology A - Assignment 1: Cell Membranes and Temperature Background Theory Beetroot contains betalain pigments within it’s vacuole‚ which gives it it’s purple-red colour‚ it’s this pigment which leaks out as the beetroot is heated and the cells membrane begins to break down. The practicals aim is to show the effect of temperature on the cell membrane by observing the colour change of the water the beetroot was placed in. The cell membrane is important as it controls the substances enters and
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Lecture: Plasma Membrane and Transport I. Structure of the Plasma Membrane A. plasma membrane - the surface encapsulating a cell B. Fluid Mosaic Model 1. bilayer of phospholipids a. hydrophilic heads - P04 end "water" "loving" attracted to water on inner/outer parts of cell b. hydrophobic tails - fatty acids "water" "fearing" attracted to each other on inside of bilayer c
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PLASMA MEMBRANE SELECTIVE PERMEABILITY= allowing some substance to cross it more easily than others composed of: Phospholipids Proteins Carbohydrates Cholesterol FLUID MOSAIC MODEL Phospholipids are primary lipids(constantly moving‚ fluidly) AMPHIPATHIC-containing hydrophobic and hydrophilic regions Mosaic part=not made of one thing Freeze-fracture studies:way to view what’s inside FLUIDITY OF MEMBRANE Move within bilayer Most of lipids and some proteins‚ drift laterally
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Biology Coursework Hypothesis: To investigate the effect of different concentrations of ethanol on the permeability of beetroot cell membranes. Prediction: By exposing a membrane to a solvent‚ ethanol‚ it will increase its permeability. So the higher the concentration of the solvent‚ the more permeable the membrane will be. But if the concentration of the ethanol is beyond a certain limit‚ it may break down the cell membrane to the point where there is in fact no overall effect as the ethanol
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How is a cell’s membrane structure suited to its functions? Throughout the past century‚ scientists have been able to conduct more research on the structure of a cell membrane and understand its components and functions. The present agreed on model‚ created in 1972 by S. J. Singer and G. Nicolson‚ is called the fluid mosaic model. This model depicts that proteins (integral and peripheral) form a mosaic since they are floating in a fluid layer of phospholipids‚ which makes up the components of
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Membrane Functions: Aim: To demonstrate the process of osmosis using a chicken’s egg Hypothesis: I predict that the egg’s mass after 10 min. in the 5% salt solution would increase due to and balancing out the solution. In the 10% salt solution‚ the egg’s mass would decrease since there is a high amount of salt. In the dilute water solution‚ the egg’s mass will increase‚ as the membrane would take in that water. Materials: 1- One fresh egg 2- One plastic spoon 3- One plastic fork
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for the description of all biological membranes • Transmembrane segments of membrane proteins anchor membrane proteins in the lipid bilayer. • A ganglioside is not a phospholipid. • Thin-layer chromatography separates lipids based on hydrophobicity. • Unsaturated fatty acids have double bonds and increased membrane fluidity. • Cholesterol increases fluidity at low temperatures and decreases fluidity at high temperatures. • Ankyrin is a peripheral membrane protein found in erythrocytes. Therefore
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Investigating the Effect of Temperature on the Permeability of Membranes The permeability of membranes can be altered in several ways. From previous preliminary work I know that reagents‚ for example detergents and alcohol alter the arrangement of the phospholipids in the membrane allowing substances to leak out of the cell. Temperature also affects the membrane. As membranes relay on protein molecules to allow molecules to enter and leave the cell through facilitated diffusion the temperature must
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