Experiment on Cell Membrane

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

Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.

Substance A and B were weighed; Substance A weighed 0.502 g and substance B weighed 0.503 g. Both substances were put into two different test tube with approximately 8 ml of DI water into the test tub. Substance A and B were stirred and B dissolved while A did not. This shows that B is soluble in water compared to A. Thus, shows that B is soluble in water than A. The reason why B is soluble in water is because it has a higher dipole moment than A. With a higher dipole moment, it shows that it is soluble in water since it is polar and the bonds were easily broken.

Those cells must receive nutrients and gases in order to undergo the metabolic processes that maintain homeostasis. In paragraph form, explain how you think the nutrients and gases enter the cell. Distinguish between the molecules that can enter by diffusion by simply moving across the membrane and those that must expend energy to cross the cell membrane.

The objective of this experiment is to develop an understanding of the molecular basis of diffusion and osmosis and its physiological importance. Students will analyze how solute size and concentration affect diffusion across semi-permeable membranes and how these processes affect water potential. Students will also calculate water potential of plant cells.

The purpose of this experiment was to test diffusion of molecules across the cell membrane to see which factor of time, concentration, and mass took effect of increase or decrease of diffusion over time.

In this lab, we are going to learn how the stress of temperature affects fresh beets. We have come to learn that cell membranes organize the chemical activities of cells. All cells are made of plasma membranes, often called fluid mosaics. It is sometimes described as a mosaic because it is made of protein molecules that are embedded into phospholipids. Phospholipids are the main structural support of the membrane and the proteins perform most of the functions of a membrane. Together they form boundaries or barriers between the cell itself and its surroundings, like the membrane of an egg. Plasma membranes also control what substances come in and out and also dispose of the

Because water is polar, water can only ‘adhere’ to other polar substances. After the water on the penny has spilled over. On a molecular scale, the hydrogen bonds are being broken. After completing this experiment, we concluded that due to the amphipathic properties of the soap detergent, the penny would not be able to hold as many drops as a penny without the soap. Again, this is because soap is non-polar and in order for water (water is polar) to ‘mix’ with another substance, that other substance has to be polar as

All cells in the human body are surrounded by a plasma membrane made up of lipids and proteins which form a barrier. The proteins and lipids in the membrane occupy different roles. The lipids create a semipermeable barrier and the proteins are part of a cross membrane transport. To pass through the membrane a substance goes through a transport known as diffusion. Diffusion is movement of molecules from a high area of concentration to an area of low concentration. There are two different forms of diffusion. One example of diffusion is known as simple diffusion, an unassisted movement of dissolved substances through a selectively permeable membrane (Marieb pg. 54). The

A biomolecule can dissolve in water if it can form significant non-covalent interactions with the solvent molecules.

Cells in all living things have an outer layer known as the cell membrane. The structure of the cell membrane consists of the phospholipid bilayer organized by the arrangement of hydrophilic heads and hydrophobic tails. It is a selectively permeable membrane, where it divides the outer environment from the interior of the cell. It can control substances moving in and out of living cells. Certain molecules like gases, water, and food are permitted to pass the membrane through the method of diffusion. Diffusion refers to the process in which molecules move on the concentration gradient, where they move from an area of high concentration to an area of low concentration. A type of diffusion is known as osmosis. It is the diffusion of water moving across the selectively permeable membrane. In this lab, students will be using eggs to construct an experiment to get a better study on how osmosis works in a cell. The eggs will be soaked in vinegar solution to remove their shells to expose each inner layer that resembles a selectively permeable membrane. The egg shell is composed of calcium carbonate that would dissolves in acidic solution such as vinegar. In the chemical reaction, it releases carbon dioxide gas. After the removal of the egg shell, it will be ready to be able to construct the experiment.

1. Chamberlain et al. Effects of Tonicity on Cell Membrane . Human Physiology Labratory Manual, 8th Edition, Expt 6 part C and D

Iodine is able to pass through a membrane but starch cannot. From the video “Science Experiment diffusion through a membrane”, we observed the starch turning dark blue after being placed in the iodine solution. This means if the starch and iodine are placed together, separated by a selectively permeable membrane, the iodine will diffuse, a type of passive transport, through the membrane into the starch but not the other way around. This happens because the membrane is selectively permeable, meaning only certain molecules and objects are able to pass through. Since the iodine molecules are smaller than the starch, the iodine is able to diffuse through, while the starch molecules are too big to. We can see that size is the reason why iodine

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

Another factor affecting the solubility of the olive oil, vegetable oil, crisco, and lard is the principle of hydrophobic interaction. Hydrophobic interaction refers to when nonpolar solutes are in the presence of polar solvents, mainly water. When this happens, the