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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The Semipermeability of Cell Membrane to Different Osmotic Environments Using Dialyzing Bag Model1 Sittie Johaynnah M. Sambarani Group 3 Sec. I-1L December 17‚ 2012 ------------------------------------------------- ------------------------------------------------- ------------------------------------------------- ------------------------------------------------- 1 A scientific paper in partial fulfillment of the requirements in Biology 10 Laboratory under Professor Junaldo
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The plasma or cell membrane exhibits ability for the cell to discriminate in its chemical exchanges with its environment and this makes cell membrane fundamental to life. This property can only be possible because of the cell membrane’s selective permeability (Campbell and Reece‚ 2002). The structure of the membrane can be best illustrated by the fluid mosaic model where the membrane is said to be a fluid structure with various proteins embedded in or attached to a bilayer of phospholipids (Campbell
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3.1 BIOLOGICAL MEMBRANES 3.1.1 Properties of Cell Membranes • Separates living cell from its nonliving surroundings. • 8 nm thick. • Selectively permeable - allows some substances to cross more easily than others. 4.1.2 Fluid Mosaic Model • Singer and Nicolson (1972) - plasma membrane is a mosaic of proteins dispersed within lipid bilayer‚ with only bilayer‚ the hydrophilic regions exposed to water. Hydrophilic region of protein Phospholipid bilayer Hydrophobic region of protein
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plasma membrane of a cell is extremely important to the transportation of substances into and out of the cell. The outer membrane of a cell is made up of lipids and proteins. Most of the lipids in plasma membranes are phospholipids. The phospholipids have a hydrophilic head and two hydrophobic tails. When engulfed in water‚ they arrange themselves such that all the hydrophobic tails clump together‚ surrounded by the hydrophilic heads‚ protecting the tails from the exposure to the water. In cells‚ which
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stress that various alcohols have on biological membranes. Using five solutions of differing alcohol concentration for each of the three alcohols; methanol‚ ethanol‚ and 1-propanol and a small slice of beet‚ the stirred solution was placed into a plastic cuvette and then into a spectrophotometer and the absorbance of alcohol solutions were determined in order to conclude which alcohol and concentration of alcohol had the greatest effect on biological membranes. The results showed that the most non-polar
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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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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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Transport Across The Plasma Membrane Intracellular Fluid (ICF) – The two thirds of your body fluid contained inside body cells. (Intra = within). The cytosol of the cell. Extracellular Fluid (ECF) – Fluid outside the body cells. (extra = outside). Interstitial Fluid – The ECF in tiny spaces between cells (inter = between). Plasma- the ECF in blood vessels. Lymph- The ECF in lymphatic vessels. Solute – Any material dissolved in fluid. Solvent- The fluid a Solute is dissolved in. Concentration
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½Give an account of the structure and properties of Biological membranes. Include details of the modifications of membrane structure found in different specialised cells and organelles½ The Fluid Mosaic model was codified by Singer and Nicolson in 1972. It describes the structure and properties of the cell membrane very simply. Every membrane consists of a Phospholipid bilayer. This is simply two layers of phospholipid molecules that come together due to their unique properties. The heads of the
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