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
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
In life, it is critical to understand what substances can permeate the cell membrane. This is important because the substances that are able to permeate the cell membrane can be necessary for the cell to function. Likewise, it is important to have a semi-permeable membrane in the cell due to the fact that it can help guard against harmful items that want to enter the cell. In addition, it is critical to understand how water moves through the cell through osmosis because if solute concentration is unregulated, net osmosis can occur outside or inside the cell, causing issues such as plasmolysis and cytolysis. The plasma membrane of a cell can be modeled various ways, but dialysis tubing is especially helpful to model what substances will diffuse or be transported out of a cell membrane. The experiment seeks to expose what substances would be permeable to the cell membrane through the use of dialysis tubing, starch, glucose, salt, and various solute indicators. However, before analyzing which of the solutes (starch, glucose, and salt) is likely to pass through the membrane, it is critical to understand how the dialysis tubing compares to the cell membrane.
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.
If the concentration of one side of the membrane is greater than the molecules will travel from the higher to lower concentration. Eventually there will be a dynamic equilibrium and there will be no net movement of molecules from one side to the other. Osmosis is the diffusion of water. Like diffusion, the water moves from a region of higher water potential to a region of lower water potential.
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.
“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).
An example of simple diffusion is osmosis. Facilitated diffusion on the other hand is dependant on carrier proteins to transport it across the membrane. Diffusion is essential for many organisms as it is a feature of a number of processes which control and supply vital substances to the body in order for basic survival. A few of these are discussed below. Gas exchange is one of these processes.
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.
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...
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
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...
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 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 ...