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Methods of Transport Across a Membrane

In plant and animal cells, there is a cell membrane that helps maintain the structure of a cell and function. The cell membrane is a biomembrane or biological membrane, which separates and protects the membrane interior cell from its outside environment. It also acts as a selective barrier within or around the cell. The cell membrane is selectively-permeable to ions and organic molecules. The selectively-permeable membrane also controls the movement of substances in and out of cells, by selecting certain kind of molecules. The cell membrane consist of phospholipid bilayer, which is composed of hydrophilic heads and hydrophobic tails with surrounded proteins, which are involved in a range of cellular processes such as Channels for passive transport , cell adhesion and pump for active transport. Due to, the cell being selectively-permeable, only hydrophobic solutions can pass through it by simple diffusion .Thus, not all molecules can pass through it directly , so molecules are being transmitted or pumped into the cell by protein channels or any other method of transport.
There are many methods of transport across membranes. Simple diffusion is the passive transport of non-polar, hydrophobic molecules from a high to low concentration. Osmosis is the diffusion of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. The semi-permeable membrane allows only certain selected particles or molecules, to pass through. Osmosis’s direction of diffusion is determined by its total solute concentration. There are three types of solutions that explain the movement of water (Osmosis).
Hypertonic solution that has a high solute concentration compared to its surroundings. When an animal cell is placed into a hypertonic solution it loses water and shrinks, because water molecules move across the semi permeable membrane from inside of a cell into the surroundings from a region of high concentration to a region of low concentration.
Hypotonic solution has a low solute concentration compared to its surroundings. When an animal cell is placed in a hypotonic solution, the cell is more likely to swell or even die, because the water moves from the surrounding into the cell from a region of higher concentration to a region of lower concentration.
Isotonic solution is one where there is no difference between solute concentrations across the semi permeable membrane. As a result, there is no net movement of water across the membrane, which makes it a normal cell. There are different types of solutions in plants and animals. In animals Hypertonic solution is called Lysed. Hypotonic solution is called Shriveled and Isotonic solution is called Normal.
Research question: How much is the mass of an egg affected by the concentration of solution it is immersed in?
Hypothesis: Cells survival depends on balancing water uptake. According to my knowledge of Osmosis, it is the diffusion of water across membrane. Simple diffusion is the passive transport of non-polar, hydrophobic molecules from a high to lower concentration. Direction of Osmosis is determined by comparing total solute concentrations. There are three different kinds Osmosis. Hypertonic solution passes through membrane from high concentration of solutes to less water concentration. Thus it shrinks. The second kind is Hypotonic solutions, it passes through the membrane from less solute concentration to more water concentration. Therefore it gains a lot of water, and the cell may burst. The third is Isotonic solution, which passes through membrane from equal concentration of solutes to equal concentration of water. Based on my hypothesis, I predict that in higher concentration of NaCl solution, mass will be higher, as the water will be lost .Where in lower concentration of NaCl solution, the mass will be lower, because the egg is more concentrated than the solution, and therefore it will take more water and gain mass in a certain period of time.
Independent variable: The changing variable will be the different concentration of NaCl solution (1M, 2M ,3M, 4M and 5M).These concentrations of NaCl solution are changed , to determine the change in mass of an egg. The change in mass will be determined by dividing the initial and final reading of an eggs mass.
Dependant variable: The initial and final mass of an egg in different concentrations of NaCl solution.
Controlled variable: The time will be controlled by using a stopwatch, because each NaCl solution should be kept for 6 hours, to then determine the final mass of the eggs.
Materials: 5 Beakers of 3 Ã- 250mL beakers.
Electronic balance, set at 0 grams.
Spoon and paper towels.
Sodium chloride solution, with different concentration of NaCl solution (1M, 2M, 3M, 4M and 5M).
5 fresh hen’s eggs.
Stop watch
Google.Omosis.2006.http://www.purchon.com/biology/osmosis.htm(Accesses on the 20th of November, 2010).
Google. Cell structure.2010. http://www.tutorvista.com/biology/basic-cell-structure (Accesses on the 26th of November, 2010).
Method: Place 5 eggs in 5 beakers of dilute acid overnight, for 24 hours to remove the hard shell leaving the membrane intact. Be aware of not destroying the membrane by removing small pieces.
Carefully remove the eggs from the acid with a spoon and rinse under a tap.
Place the eggs on paper towel and gently pat the eggs, till they dry. The eggs should then be measured on a balance, and their mass must be recorded.
To start the reaction, place the eggs on a balance and record, each of their masses in your data table. Also, put a title for the table.
Label 5 beakers, to A, B, C, D

Reservoir Limit Testing Strategies

Reservoir limit testing is a powerful tool used to estimate the reservoir volumes of finite systems. The procedure was first introduced by Jone’s(1) which is restricted to only depletion drive reservoirs due to the boundary conditions assumed to solve the redial pseudo-steady-state flow diffusivity equation. But in water and/or gas cap drive reservoirs, water influx and gas intrusion affects test results and then the conventional procedure of Jone’s method for bounded systems is not applicable.
An analytical method has been developed to estimate the boundary of the reservoirs producing under moving boundary systems (bottom water and/or gas cap drive mechanisms) by applying the principle of superposition theorem to reflect the reservoir pressure drop pulses at the free levels of the displacing fluids to estimate the time at which the pseudo-steady-state prevail.
Introduction The reservoir limit testing analyzing reservoir performance to estimate the original hydrocarbon in place is one of the fundamental tasks that reservoir engineers perform. The testing procedure is performed by flowing a well either at constant or variable flow rates (1, 2) until pseudo-steady-state flow condition start to prevail. During this period of the flow regime, the bottom hole flowing pressure exhibit a linear function of time and the slope is indicative for reservoir pore volume.
This method of analysis was first introduced by Jone’s (1) 1956 for bounded systems. While, in water and/or gas cap drive systems, the effect of water influx and/or gas intrusion towards the oil zone will be to increase the average reservoir pressure, this increase in pressure is felt throughout the conventional test and affects the pressure measurements.
Kaczorowsk (3) 1993, use the concept of Jone’s definition for pseudo-steady-state flow regime to develop an empirical method to determine the movable hydrocarbon volumes in water drive systems. The procedure require to achieve two reservoir limit tests performed using two different flow rates and require to reach the pseudo-steady-state flow regime for each. This method is applicable to determine the remaining movable hydrocarbon volumes in water drive gas reservoirs of small to moderate size and oil reservoirs that are producing above the bubble point pressure.
Reservoir limits testing in moving boundary systems New analytical methodology has been developed to estimate the boundary of the reservoirs producing under bottom water and/or gas cap drive mechanisms (moving boundary systems) by assuming the fluids interfaces levels between oil-water and / or oil-gas as a no-flow boundary during the early period of production in which the transient flow regime prevail. During this period of the flow, the fluids interfaces still not offer any response to that pressure drop pulses created in the reservoir during the test.
Meanwhile, the principle of superposition (image) theorem used to reflect the created pressure drop pulses at the free levels of the displacing fluids to estimate the time at which the reservoir pressure drop pulses reach the interfaces positions.
The principle of superposition could be applied at the fluids interfaces levels of zero capillary pressure at which the pressure gradient is zero. This methodology suggests reflecting the transient pressure drop pulses behavior that is created in the oil zone as a results of oil production activities at the free levels of the displacing fluids interfaces (water and gas) to estimate the fluids boundaries rather than reflecting a boundary to predict the pressure drop behavior that is conventionally used in bounded systems as shown in schematic drawing (1).
The created pressure drop pulse in the reservoir due to oil production operation will travel at specific rate depending on the displaced fluid (oil) and the reservoir zone characteristics to reach the existing displacing fluids interfaces in contact with oil zone(4

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