Osmosis Lab Report

Cells and molecules in the environment are constantly moving and changing, for cells to function properly there is a need for equilibrium to be met. The size of the cell and the solution outside of the cell affects the rate of diffusion and osmosis in the cell. Cells are constantly trying to reach an equilibrium with the molecules and substances around it, which is why there are such terms as: hypertonic, hypotonic and isotonic. The procedures allowed testing of whether or not surface area or volume increased diffusion and how different substance control diffusion. Cells are constantly moving to reach equilibrium through diffusion and osmosis.

Osmosis is described in one of three ways when comparing more than one solution. The cell’s external and internal environment helps determine tonicity, which is defined as how the cell reacts to its environment. When the cell’s environment is equal in osmolarity to itself and there is no change, it is considered an isotonic solution. When the environment has a higher osmolarity, shrinkage occurs and it is considered a hypertonic solution. When the environment has a lower osmolarity, swellings occurs and it is considered hypotonic.

In the case of this experiment, if a cell is placed in a hypertonic solution as seen above in the figure 7a, water will leave the cell to move down its own concentration, and the cell shrinks. In the isotonic solution as seen above in figure 7b, the concentration of solute and water are equal so there is no net movement in the flow of water outside or inside the cell, so the shape of the cell does not change. Finally, in the hypotonic solution in figure 7c, the net movement of the water is inside the cells which makes the cells swell

Introduction: The biological membranes are composed of phospholipid bilayers, each phospholipid with hydrophilic heads and hydrophobic tails, and proteins. This arrangement of the proteins and lipids produces a selectively permeable membrane. Many kinds of molecules surround or are contained within

Osmosis is the passive movement of water from an area of low solute concentration to an area of high solute concentration, normally across a membrane which prevents the movement of solvent. This is a process by which materials may move into, out of, or within cells. Osmosis doesn’t depend on energy provided by living organisms but is affected by the properties of the cell membrane. The rate of osmosis is dependent on such factors as temperature, pressure, molecular properties such as size and mass, and the concentration gradient. In osmosis, the relationship between a solute’s concentration outside of cell and inside of a cell is described in terms of the tonicity of the solution outside of the cell. A cell is in a hypotonic solution when the solute is more concentrated inside the cell and therefore water moves into the cell. In this solution the cell swells as water enters, this may continue until it ruptures or hemolyzes. In the reverse condition, the cell is in a hypertonic solution

Osmosis is a special type of diffusion. It is the diffusion of water molecules across a semipermeable membrane (a membrane that allows for the diffusion of certain solutes and water) from an area of higher water concentration to one of lower water concentration. For example, if a 1 M aqueous starch solution is separated from a .5 M aqueous starch solution by a semi-permeable membrane, then water molecules will move from the .5 M aqueous starch solution (higher water molecule concentration) toward the more concentrated 1M starch solution (lower water molecule concentration) until an equilibrium of water molecules exists between the two solutions. Since the semi-permeable membrane did not allow for the passage of starch molecules, the 1M-starch solution will gain in volume as the water moves in (Figure 3).

All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.

I hypothesized that if the concentration would increase, then the osmosis would too in the same way. Such as the concentration goes from 20% to 40%, the rate of osmosis doubles as well. Even after finding out the human error from the lab prep crew, who switched the 30 percent with the 40 percent concentration, making our data for 30 percent truley for 40 percent and vice versa. If you look at figure xx, you can see that the osmosis rate for 20 percent and 30 percent, which we now know is truley 40 percent, almost triples. From when the concentration goes from 20 percent with a osmis rate of .039g/ml to 40 percent with a osmic rate of .095g/ml.

In osmosis, the flow of the water from or to a cell depends on whether the cell is immersed in a solution that is isotonic, hypotonic, or hypertonic to the solution. If the cell is isotonic to a solution, this means that the solute concentration of a cell and its environment is the same and therefore there will be no movement of water. If the solute concentration is lower than that of the cell, then water will flow into the cell, causing it to expand. If the solute concentration is lower than that of the cell then water will flow out of the cell, causing it to shrink.

The extent of osmosis will depend on the difference in concentration of the two solutions on either side of the membrane. Therefore this allows water to move from the low concentrated solution, pass the semipermeable membrane, and into the high concentrated solution. This movement of water allows to repeatedly enter and leave the fluid compartments depending on any changes in the conditions of different parts of the body.

Throughout this experiment I learned the basis for Osmosis. Our experiment and data helped me further understand the variation of osmosis and water potential. In our first experiment we learned that the overall mass will increase due to the starch and glucose in the dialysis bag. This is what I predicted to happen since the concentration of water is lower in the bag than in the distilled water. The water always moves down its concentration gradient by osmosis.

Analysis and Discussion: Part one of the experiment came as bit of a surprise to me, and the group. Hypothetically glucose is too large to move through a selectively permeable membrane, and requires the use of a transport protein to break through the membrane, and this would be an example of . However, this can be accounted for, as the pores in the tubing are not nearly as small as the ones in an actual cell and allowed for the glucose to enter the H2O+1KI solution. The water was able to freely pass thought the tubing due to its small size, and due to this its polar charge does not play a large factor in the process of osmosis.

In biology, I learned that cellular boundaries can be permeable. Initially, this concept was intriguing in and of itself, that cells can release and absorb information to perform necessary functions. The phrase “boundaries are permeable” has remained with me three years later.

Osmosis is when water passes through a cell membrane, it is also form of a diffusion, which is a form of passive transport. Osmosis will continue to until an equilibrium is reached which is when the solutions are isotonic. This means that the solution has the same amount of solute on both sides. If the solution is hypertonic, it has more solute in the solution. In this situation water will move towards it. if the solution is hypotonic, it has less solute in the solution. Whereas in this situation, water will move out of the solution.

Only uncharged, small, polar molecules, (such as water) and hydrophobic molecules, (such as oxygen, carbon dioxide) and lipid-soluble molecules (such as hydrocarbons) can freely pass across the membrane. All ions and large polar molecules (such as glucose) are not permeable to the membrane.