LAB #1: Cell Transport Mechanisms and Permeability
Conneda Salianekham
BIOL 2401-C70
Dr. Ruben D. Ramirez
2/8/2015
Abstract
The cells are the basic building blocks of all living things. One of its significance and unique characteristics is its ability to be selectively permeable with its plasma membrane. The outer membrane mechanisms transports through its bilayer which are important in maintaining homeostasis in the cells and the entire body. To further understand these mechanisms, five experiments were conducted. These experiments were conducted over simple diffusion, facilitated diffusion, osmotic pressure, simulating filtration, and active transport. These studies were obtained by understanding the changing and observing the different variables of how they affect transport through the membrane.
Materials and Methods
Simple Diffusion
The rate of diffusion affects the size of the molecule and the plasma membrane. The larger molecule will diffuse more slowly than the smaller molecule. If the membrane is composed of lipid portion, only lipid soluble molecules can pass through. In the urea, the molecules were not able to diffuse through the 20 MWCO membrane due to saturation. The urea was not able to diffuse through because of the size of the pores. According to, Urea | CH4N2O - PubChem. (n.d.), “The molecular weight of the urea is 60.07”. The weight of the molecular urea were too large to enter the pores of the 20 MWCO. The next experiment was to diffuse glucose and albumin through the 200 MWCO membrane. Glucose could diffuse through the 200 MWCO while albumin could not diffuse through the membrane. It was due to the molecular weight between them. According to, C6H12O6 - PubChem. (n.d.), “The glucose ...
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Urea | CH4N2O - PubChem. (n.d.). Retrieved February 8, 2015, from http://pubchem.ncbi.nlm.nih.gov/compound/urea#section=Top
Tables
Table 1
Figures
Figure 1
Figure Legends
Table 1: Relative Permeability of Muscle Capillary Pores to Different-sized Molecules
Lists substances in order from the molecular weight and permeability
Figure 1: Osmotic Pressure
Explains the flow of the osmotic pressure from membrane permeable to both solutes and water and membrane permeable to water, impermeable to solutes
The water concentration is now even on the inside and out. This process is called osmosis. Part B: Aim: To investigate the action of a differentially permeable membrane. Method: See attached.
This cell membrane plays an important part in Diffusion. Cell membrane and Diffusion Diffusion is the movement of the molecules of gas or liquids from a higher concentrated region to a lower concentration through the partially permeable cell membrane along a concentraion gradient. This explanation is in the diagram shown below: [IMAGE] Turgor When a plant cell is placed in a dilute solution or a less concentrated solution then the water particles pass through the partially permeable membrane and fill the cell up with water. The cell then becomes Turgor or hard. An example of this is a strong well-watered plant.
“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).
...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.
The continuous supply would help in maintaining a concentration gradient which is essential for diffusion to take place. The 2 main types of diffusion are simple and facilitated. Simple diffusion is when a small, non-polar molecule passes through a lipid bilayer. In this type of diffusion, a hydrophobic molecule moved into the hydrophobic region of the membrane without getting rejected. A key feature is that it does not need a carrier protein to take place.
Eukaryotic plasma membranes in a fluid state have been found to contain a low cholesterol content of approximately one cholesterol to every 16 lipid molecules (Harby 2001). The effect of additional cholesterol in a plasma membrane on cell membrane fluidity and survival was studied in an experiment by Purdy et al. (2005), who used Chinese hamster ovary cells (CHO) and bull sperm to test this effect. Assuming that changing a membrane's cholesterol content can modify its fluidity at differe...
Here, deep in the lungs, oxygen diffuses through the alveoli walls and into the blood in the capillaries and gaseous waste products in the blood—mainly carbon dioxide—diffuse through the capillary walls and into the alveoli. But if something prevents the oxygen from reaching t...
Most cell membranes are like that, being permeable to water and some solutes only. Osmosis is therefore the diffusion of water through a partially permeable membrane. The basic principles of diffusion apply here.
However not in sucrose, the RBCs were semi-permeable. RBCs diffuse in the water around five minutes, but in glycerol RBCs diffuse in fifteen minutes. Several factors are involved that affect the rate at which the RBCs diffuse, could have been because of the size, polarity, or the charge of the molecule. Urea is the carbonic acid found in urine, blood, and lymph; it is formed in the liver from amino acids and ammonia. It is important that urea is permeable because the amount of urea in the body is essential because it helps undergo waste product. Glycerol is combination of sugar and alcohol. This solution is an important component for storage of fats that are ingested into the body as food, this one good reason why glycerol is permeable. Sucrose however has low permeability which is why sucrose has a slow rate of diffusion and glycerol and urea on the other hand has fast rates of
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.
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 ...
Cellular membranes are complex mixtures of proteins and lipids. Cell membranes are composed of a phospholipid bilayer, consists of two leaflets of phospholipid molecules and their fatty acid chain form the hydrophobic interior of the membrane bilayer; and proteins that span the bilayer and/or interact with the lipids on either side of the two leaflets. Transmembrane proteins are the type of membrane proteins which span the entire length of the cell membrane. They are embedded between the phospholipids and provides a channel through which molecules and ions can pass into the cell. They enable communication between cells by interacting with chemical messengers. Membrane proteins were classified into two comprehensive categories- integral and
result and will be flaccid. Water will be lost from the tissue and Depending on the amount lost, the weight and length will decrease. accordingly. Then we will be able to do that. If a surrounding sucrose solution has a higher water potential than the tissue then water will move by osmosis from the solution into the tissue.
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.
The symporter brings two molecules into the cell at the same time. Sym means with and port means carry. Sodium (NA-) pairs up with a molecule like glucose and amino acids to bring it into the cell. Overall, the sodium gradient uses the pumps ...