Computer Simulation of Cell Transport Mechanisms and Permeability: Passive Processes and Active Processes
In this lab we will establish a difference between the two types of cell transport mechanisms and their permeability. The first type of cell transport is passive processes which are driven by concentration or pressure differences in the interior and exterior of the cell. The second type is active processes which use energy known as ATP to power the transport. There are two main types of passive processes called diffusion and filtration. This can be split into different types such as simple diffisuion, facilitated diffusion, osmosis and filtration.
The objective of these experiments is to provide information on the passage of solutes and water through semi permeable membranes and relate them back to the study of actual living membranes in the human body. The purpose is to better understand how and why membranes use certain types of passive or active processes to move solutes and water across its membrane.
Simple diffusion is the net movement of substances from a region of high concentration to a region of low concentration. It will move down its concentration gradient meaning the molecules will eventually become evenly distributed throughout the environment. In this experiment NaCl, urea, albumin and glucose will be used to show how different substances move differently across the membrane. If a substance is not able to go across a membrane then the size of particles are to large to pass through, but other particles depending on size should still be able to pass through.
Facilitated diffusion is also the net movement of substances moving down their concentration gradient, but with the help of carrier proteins. Which are proteins that bind to substance or molecule and help it transport across the membrane. In this experiment we will use different concentrations of glucose to show the affects carrier proteins have on its permeability. If glucose is not able to pass through the membrane then either there are no carrier proteins present to help or not enough to help finish the process.
Osmosis is a special form of diffusion which solely relates the movement of water thorough a membrane. It occurs when there is a difference in water concentration on both sides of a membrane. The concentration of water in a solution depends on the number of solutes present. It will always move to the solution with the highest concentration of solutes. In this experiment NaCl, albumin, and glucose will be used to help show the movement of water across a membrane. If water is not able to diffuse across a membrane then it has either reached equilibrium or the concentration of solutes was lower on the other side.
Filtration is the process where water and solutes pass through a membrane from an area of higher hydrostatic pressure to an area of lower hydrostatic pressure. Meaning the pressure on either side of the membrane is what pushes or decides whether or not the water and solutes will be able to pass through. In this experiment NaCl, urea, glucose, and powdered charcoal will be added to water to help show how solutes and water will pass through a membrane depending on the pressure. If the hydrostatic pressure is high enough then all the solutes and water will able to pass through the membrane.
Active transport, the only active process, uses cellular energy ATP to help move solutes across the membrane. This is used when all other passive processes are not able to get a solute or substance across the membrane for a number of reasons. In this experiment we will demonstrate a sodium potassium pump to illustrate how ATP is needed to get both NaCl and K across the membrane. If there is not enough ATP for the transport then the transport will not occur.
Materials and Methods
For these experiments I used the Physio EX 8 on the my lab and mastering website study area. I followed the instructions...
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