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
...s a component monomer of starch. As a monomer as opposed to a polymer, it is much smaller and would thus be able to cross the plasma membrane. However, glucose is a larger solute than the component ions of salt, thus meaning that simple diffusion would not be sufficient. Instead, facilitated diffusion would be needed to transport the glucose. However, in the dialysis tubing, there is no facilitated transport like there is for the plasma membrane. Thus, the glucose may pass through the dialysis tubing, but it would not be due to transport, but the artificial enlargement of the passages in the dialysis tubing. Water would move freely inside and outside of the cell, however, because there is a greater solute concentration inside the cell, the water would diffuse through osmosis into the cell model, increasing the final mass of the dialysis tubing and causing cytolysis.
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
Activity 3: Investigating Osmosis and Diffusion Through Nonliving Membranes. In this activity, through the use of dialysis sacs and varying concentrations of solutions, the movement of water and solutes will be observed through a semipermeable membrane. The gradients at which the solutes NaCl and glucose diffuse is unproportional to any other molecule, therefore they will proceed down their own gradients. However, the same is not true for water, whose concentration gradient is affected by solute ...
The experiment is aimed at giving a better understanding of the osmosis process and the different conditions in which osmosis occurs. INTRODUCTION When a cell membrane is said to be selectively permeable, it means that the cell membrane controls what substances pass in and out through the membrane. This characteristic of cell membranes plays a great role in passive transport. Passive transport is the movement of substances across the cell membrane without any input of energy by the cell.
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).
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.
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.
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,
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)
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.
there would be no flow of water into or out of the cell so the cell
So how big are cells? Most human cells are about ten microns in diameter. This is about o...
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