Why do some materials move through the dialysis tube (membrane) and others do not? We placed a dialysis tube containing a starch solution, glucose solution, and iodine into a beaker filled with distilled water. The goal was to to see what material would transport in and out of the dialysis tube. After about 24 hours, the dialysis tube no longer was white like it was originally (due to the glucose solution that was in it). We put a glucose strip into the distilled water and found that there was indeed glucose inside the water. The starch and iodine did not transport due to their molecules being too large to passively transport. We realized that the glucose diffused into the water because the tube held a higher concentration of glucose than the distilled water surrounding the tube (hypotonic solution). Since the glucose molecules were small enough to transport, an equilibrium of glucose was able to occur between the tube and the water. This is how strainers work. This is why our cells don’t require any energy to take in water because the water molecules are small enough to transport passively.
What about material that diffuses through a cell membrane? We placed an egg that had an original size of 13.5 centimeters in circumference into 250 mL of vinegar. After 24 hours, the egg’s size increased to 17.3
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We took a 1, 2, and 3 centimeters squared cubes and placed them in vinegar for 10 minutes each. We found that for all the sizes, the diffusion depth was 3 millimeters for each one. This means that the diffusion rate is 0.3 mm/min for every size of the same shape. This means that no matter the size, they still diffuse at the same rate. This is why cells are small, because since the diffusion rate is the same no matter what, the material diffused can reach the center easier for smaller
It started one day in a science classroom. That is where I learned about diffusion. Diffusion is the movement of a substance across a membrane, due to a difference in concentration, without any help from other molecules. (Unknown, 2) In the egg lab the egg experienced diffusion over the course of several days. During the lab I also learned about hypertonic solutions and hypotonic solutions. The hypertonic solutions concentration of the cell is less than the outside of the cell. (Trent, 1) Hypotonic solutions have a higher concentration in it than the area surrounding it. (Trent, 1) I learned about hypertonic solutions when we placed the egg in corn syrup which caused the egg to deform and become squished. I learned about hypotonic solutions when we placed the egg in water which caused the egg to swell. This process can also be defined as osmosis which is the diffusion of water molecules across a membrane. (Unknown, 2) When we first got the egg it would be an isotonic solution meaning that having equal tension (Unknown,1) which would mean that the same amount was inside the cell as outside of it. The purpose of the experiment was to learn about diffusion, concentration gradient, passive transport,
This occurs when special carrier proteins carry solutes dissolved in the water across the membrane by using active transport. When the concentration gradient can not allow travel from one side of the membrane to the other fast enough for the cell’s nutritional needs, then facilitated diffusion is used. The transport protein is specialized for the solute it is carrying, just as enzymes are specialized for their substrate. The transport protein can be
In osmosis, the proteins only on the surface are called peripheral proteins, which form carbohydrate chains whose purpose is used like antennae for communication. Embedded in the peripheral proteins are integral proteins that can either be solid or have a pore called channel proteins. -11.07% Discussion The chart shows the percent sucrose solution that resulted in the greatest change in average egg mass was the 0% solution, while the 1.73% solution resulted in the least change. The data also suggest that the percent sucrose solution that is isotonic to an egg’s interior may be between -10% and -15%, since the average masses of the eggs did not change beyond 0.15% over a 30 minute time period. In fact, the control group displayed the least amount of change in mass (0.10%) over a 40 minute period of time.
molecules go in and out of the cell. There is no net movement of water
“The plasma membrane is the edge of life, the boundary that separates the living cell from its nonliving surroundings. The plasma membrane is a remarkable film, so thin that you would have to stack 8,000 of these membranes to equal the thickness of the page you are reading. Yet the plasma membrane can regulate the traffic of chemicals into and out of the cell. The key to how a membrane works is its structure” (Simon, 02/2012, p. 60).
Cells are grouped into three categories namely plant, animal, and prokaryotic cells. In addition, the shape and size of cells range from a few millimeter to microns. The size of a cell is indicative of its function(s). The shape of cells in living organisms may range from concave, to spherical, oval, rectangular, flat, oval, or rod-shaped. The cells can be viewed with the aid of a microscope. Every living organism possesses multicellular and unicellular cells. At the same time, the different types of cells display common structural properties. Examples include the plasma membrane and genetic composition (Jan,
The Importance of Diffusion to Living Organisms Diffusion is basically the movement of chemical species (ions or molecules) under the influence of concentration difference. The species will move from the high concentration area to the low concentration area till the concentration is consistent in the whole system. Diffusion mostly occurs in gases and liquids as these can move freely. The main features of an efficient diffusion system would be that it has a large surface area, thin membrane and a continuous supply of substances. A large surface area is needed so that high amount of substances can be exchanged at a time while the thin membrane means that the diffusion pathway would be short so that it is more efficient.
Dialysis is a process by which excess waste and water is removed from the blood to maintain a balanced proportion of contents/nutrients. Dialysis is done by using different dialysis machines which are usually very costly and sensitive. The duty to maintain a constant proportion of contents in the blood is usually done by kidneys but when they are not functioning properly the procedure of dialysis used. Therefore it is a very important and beneficial process for people whose kidneys are not functioning properly or who cannot undergo a kidney transplant due to various reasons for example blood type or reactive immune system. The process of dialysis might look very simple but there is a lot more ethical complexity related to it that will be elaborated. (White & Fitzpatrick)
there would be no flow of water into or out of the cell so the cell
Diffusion and osmosis are necessary for the efficient transport of substances in and out of living cells. Diffusion is the most common and effective transportation process between cells and their surroundings, the movement of a substance along a concentration gradient from high to low, allowing essential nutrients and compounds to be transported without expending energy. Osmosis is a special kind of diffusion, specific to water. In order to observe diffusion and osmosis in real and artificial cells, a series of experiments was put together to observe how the surface area to volume ratio effects the rates of diffusion by using agar in different shapes with different ratios, next the rate of diffusion due to tonicity was observed using different solutions with different tonicities. And lastly live plant cells were submerged in different solutions with varying water potentials to observe how was potential effects the rate of osmosis and diffusion. It was concluded that the larger surface area to volume ratio, the faster rate of diffusion, the hypertonic solutions caused water to leave a cell and the hypotonic solutions allowed water to enter a cell, and that water potential will move from high to low in an attempt to maintain equilibrium.
All things, living or nonliving, consist of atoms and molecules. These particles are constantly in motion, and this continuous motion allows for the disbursement of molecules, or diffusion. The overall net movement of these molecules will go from areas of higher concentration, to areas of lower concentration. Therefore, following a concentration gradient (Martini). The rate of diffusion of these molecules, in accordance with Fick’s law of diffusion, is directly proportional to the concentration gradient present. However, the concentration gradient is not static and will change over time and with distance, therefore changing the rate of diffusion. It is hypothesized that the two solutions being tested, Methylene Blue and Potassium Permanganate, will begin their initial diffusion in the agar gel at a quick rate, and then progressively regress over the allotted time of 1 hour. Another factors other that will have an effect on rate of diffusion is molecular size. There is a substantial difference in molecular weight between Methylene Blue (320 g/mol) and Potassium Permanganate (158 g/mol). The combined molecules present in Potassium Permanganate are lighter than those in Methylene Blue, and therefore should allow it to diffuse more rapidly.
The cell is the fundamental structural unit of all living organisms. Some cells are complete organisms, such as the unicellular bacteria and protozoa; others, such as nerve, liver, and muscle cells, are specialized components of multi-cellular organisms. Cells range in size from the smallest bacteria-like mycoplasmas, which are 0.1 micrometer in diameter, to the egg yolks of ostriches, which are about 8 cm (about 3 in) in diameter. Although they may differ widely in appearance and function, all cells have a surrounding membrane and an internal, water-rich substance called the cytoplasm, the composition of which differs significantly from the external environment of the cell. Within the cell is genetic material, deoxyribonucleic acid (DNA), containing coded instructions for the behavior and reproduction of the cell and also the chemical machinery for the translation of these instructions into the manufacture of proteins. Viruses are not considered cells because they lack this translation machinery; they must parasitize cells in order to translate their own genetic code and reproduce themselves.
So how big are cells? Most human cells are about ten microns in diameter. This is about o...
The purpose of this lab was to see firsthand the diffusion of a substance across a selectively permeable membrane. Diffusion is the movement of molecules from an area of high concentration to an area of lower concentration until both concentrations are equal, or as you could more professionally call it, equilibrium. This concept is one that we have been studying in depth currently in Biology class.
Lastly there’s the vacuole. The vacuole is a closed compartment that’s stores and keeps water inside of the cell. It sometime carries solids that have been engulfed. Vacuoles are formed by fusions of multiple membrane vesicles. They are found in both plant and animal cells, but appear larger in plant cells. Vacuoles have no key shape or size. Its size and shape is based on the need of the cell. The vacuole does more than just store water, it separates materials that can harm the cell, holds waste and small molecules and passes on unwanted