Osmolarity Lab

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.

Explain what happened to the blood cells at the various levels of concentration. Be sure to refer to the solutions as being hypotonic, hypertonic and isotonic.

In this lab experiment, half our group observed and measured osmosis using dialysis tubes that were represented as the semipermeable membrane. It is permeable to water and other small molecules but is impermeable to larger molecules such as the sucrose solution used in each of the four beakers and tubing. The other half of our group observed the tonicity of sheep blood to determine whether the blood was isotonic, hypotonic, or hypertonic. The 85 g/dL of NaCl solution was the ideal isotonic number in relation to the sheep blood cells as well as a reference to the other observations of the solutions.

Blood is a non-Newtonian fluid that contains many components. One such component is red blood cells. Due to the red blood cells having the tendency to clump together at low velocities, calcium chloride was added in order to cause a thrombus formation. The blood used in this experiment was sheep’s blood.

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.

Ive actually conducted an experiment where three potato strips were put into three different solution: distilled water, 10% NaCl, and 85% NaCl. The potatos were left in the solutions for fortyfive minutes. The experiment is to test different versions of osmosis. After fortyfive minutes had passed I took the potatos out of the solutions, and observed the results. The potato that was in the 10% NaCl solution was still firm, but slightly bendable. The potato strip that was in the distilled water was hard and rigid. To sum it up the effects to the potato strips were the same effects as the blood cells in the drowned victims. The hypotonic ones swelled up and gained water, while the hypertonic ones shriveled up and lost

The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.

Exercise 1: Cell Transport Mechanisms and Permeability: Activity 3: Simulating Osmotic Pressure Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Which of the following is true of osmosis? You correctly answered: c. It is a type of diffusion. 2. Which of the following occurs when a hypertonic solution is added to cells? You correctly answered: d. The cells shrink. 3. The variable that affects osmotic pressure is You correctly answered: a. the concentration of nondiffusing solutes. 4. The net movement of water would be into the cell in a You correctly answered: b. hypotonic solution.

The Electronic balance was used to find the mass of the liquids and the solids.

Water would rush out of the red blood cell, the red blood cell to shrink. When the red blood cells were placed in deionize water, this water contains no solutes and it is very dilute there was a higher concentration of solutes inside the red blood cell or present in the intracellular fluid. The water existing in the extracellular fluid had a lower concentration of solutes as distilled water does not contain any solutes; distilled water is pure. The water rushed into the cell, causing it to swell. The red blood cells were in an isotonic solution of 0.85% NaCl; the concentration of solutes in the extracellular fluid (NaCl) and the concentration of solutes in

When erythrocytes are placed in a hypotonic solution (a solution with lower concentration than the cell), water moves into the red blood cell, causing it to swell, to increase its volume and eventually burst ( haemolysis). When erythrocytes are

Osmosis is a special type of diffusion. It is the diffusion of water across a semipermeable membrane which is a membrane that is freely permeable to water but is not freely permeable to solutes, the water moves from a dilute solution to a more concentrated solution (Karp, 2010). Both diffusion and osmosis are passive transport, energy is not used in the transport. In osmosis water moves across a membrane toward the solution of greater concentration, because the concentration of water is lower there (Martini and Bartholomew., 2007).

In animal cells, the movement of water into and out of the cell is influenced by the relative concentration of solute

Therefore, hypertonic solutions, cause the cell to shrink or crenate. (Mathieson, 2013). The sheep’s blood is then placed into four different slides, and then different solutions are dropped into each slide. The solutions are .9% NaCl, 10% NaCl, and dH2O. A microscope was then used to observe any changes that occurred to the cells.

When RBCs are suspended in an isotonic solution, nothing should be observed as there will be no net water movement between the RBCs and the solution. Thus, when 200 µL of blood was added to 10mL isotonic saline (0,154 M NaCl), voltage of 0V is recorded. When RBCs are suspended in a hypertonic solution, for instance, 0.4 M NaCl, RBCs shrunk due to decrease in cell volume as water diffused out of the cells by osmosis. The protein concentration within the cells become greater and more light is scattered and a negative