Different Types of Transport Mechanisms Occuring in AEMs

Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a semi-permeable(selectively permeable) membrane is osmosis. Semi-permeable means that some molecules can move through the membrane while others can not. Diffusion and Osmosis are passive forms of transport requiring no energy. Active Transport utilizes energy in the form of ATP. Water is a solvent that can dissolve a number of substances more than any other substance. Wherever water goes, through the ground or a body, it takes along valuable molecules. Water’s chemical composition causes it to be attracted to many different molecules and be attracted so strongly it disrupts the forces and dissolves it. Water can pass through the semipermeable membrane without any help but can change the solution, on the other side of the cell membrane, depending on how much it diffuses in and out.

Sometimes one substance is transported in one direction at the same time as another substance is transported in the other direction. This is called Co- transport. In Co-tansport one of the two substances are transported in the direction of their concentration gradient utilizing the energy derived from the transport of the second substance (mostly Na+, K+ or H+) down its concentration gradient. Active transport often takes place in the

2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport.

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane

I obtained the results from the experiment supported my predictions because as the the concentration Na+ Cl- was increased from 5 mM to 10 mM (by adding more Na+ Cl-), the osmotic pressure also increased. However, after the membrane was changed to 50 MWCO, the Na+ Cl- molecules could diffuse easily through the membrane and did not caused an increase in osmotic pressure.

What two parameters are responsible for creating the movement (filtration and reabsorption) of fluid across the capillary wall?

What happens to the urea concentration in the left beaker (the patient)? It mixes with the water to balance out the structure.

The purpose of these experiments is to examine the driving force behind the movement of substances across a selective or semiperpeable plasma membrane. Experiment simulations examine substances that move passively through a semipermeable membrane, and those that require active transport. Those that move passively through the membrane will do so in these simulations by facilitated diffusion and filtration. The plasma membrane’s structure is composed in such a way that it can discriminate as to which substances can pass into the cell. This enables nutrients to enter the cell, while keeping unwanted substances out. Active

All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.

In order to assimilate diffusion through a permeable membrane potassium permanganate and methylene blue were used in experiment. The objective was to compare the rates at which the liquid compound of different molecular weight diffused through agar. This was achieved by obtaining agar in a petri dish with two wells to hold the liquid compounds. The rate was measured by time and diameter distance diffused. This process was observed for 60 minutes at 15 minute intervals.

To study the effects of hypotonic, hypertonic and isotonic solutions on plant and animal cells.

1. What two parameters are responsible for creating the movement (filtration and reabsorption) of fluid across the capillary wall?

If the solution in the left beaker contained both urea and albumin, which membrane(s) could you choose to selectively remove the urea from the solution in the left beaker? How would you carry out this experiment?

For diffusion and Gas Exchange to occur here they have to have a large surface area dependent on the size of the

small, positively-charged proton with a negatively-charged electron orbiting very fast, a model analogous to the earth orbiting the sun, or the moon orbiting the earth. Fuel cells take advantage of this structure. Using a membrane and a catalyst, hydrogen is broken up into a proton and an electron. While there are many different membrane models for fuel cells, the most appropriate one for car travel is the Polymer Electrolyte Membrane (PEM, also called the Proton Exchange Membrane). It is called this because protons are able to easily pass through the membrane. However, because the membrane does not allow electrons to pass through it, the electrons take a detour through an electrical circuit to the other side of the cell. If hydrogen is supplied into the cell at a steady rate, the stream of electrons in the electrical circuit creates electric power. However, like all batteries, you need a positive end (cathode) and a negative end (anode); in other words, the hydrogen atoms must have a “reason” to make this electrical circuit. And what is this reason? Oxygen. With oxygen at the other end, hydrogen is more than willing to create this current so that it can bind and form H2O, or water on the other end.