Essay on Physio 9.0 Lab 1:3

2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport.

Students have grouped together in their Anatomy Lab using three different types of Sucrose Bathing Solutions and three different deshelled chicken eggs. Students will learn the permeability of the cell membrane by studying the ability of a shell-less chicken egg to absorb the various sucrose bathing solutions. Students can see how membranes can regulate a cell’s interaction with its environment. The deshelled egg is semi-permeable, meaning that some molecules easily move across the cell membrane, some cannot. A cell membrane can transport materials through two general forms: Simple diffusion and Facilitated diffusion. Principles of Medical Physiology states “Facilitated diffusion, it is generally much faster than simple diffusion. Glucose and other large uncharged hydrophilic molecules have extremely slow rates of simple diffusion across the lipid bilayer but they cross the membrane much faster through facilitated diffusion.” Osmosis can be defined as the

The objective of this experiment was to test the effect of a specialized type of diffusion called osmosis, “which involves in selective transport of water molecules across a selectively permeable membrane” (Lab Manual 2nd edition). It was hypothesized that osmosis will occur when there is an uneven distribution of solute in a solvent. The more abundant the solute is in solvent, the higher the rate of osmosis through the diffusion gradient forming a hypertonic or hypotonic solution. Solvent with equal or no solute forms an isotonic solution. Throughout this lab, data was collected and compiled to analyze these effects across selectively permeable membranes. The results indicated that the water molecules indeed move from

Explain the effect that increasing the Na+ Cl- concentration has on osmotic pressure and why it has this effect. How well did the results compare with your prediction?

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.

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.

1. Explain the effect that increasing the Na+ Cl- concentration had on osmotic pressure and why it has this effect. How well did the results compare with your prediction?

The concept of osmotic pressure must be understood when studying osmosis. The movement of water from a hypotonic solution through the membrane into a hypertonic solution can be prevented by applying force or pressure on the hypertonic side. The force that must be applied to prevent osmotic movement of water from hypotonic to hypertonic, measured in atmospheres, is referred to as osmotic pressure. Solutions with greater concentrations of OAS have greater osmotic pressures because greater force is required to prevent water movement into them. Distilled water has an osmotic pressure of zero.

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.

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

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.

Osmosis is one of the most common and important processes in biology. Countless processes within the human the human body rely on osmosis and other forms of diffusion, ranging from the exhale of CO2 out of the cell to the various reactions between organelles (Nave, n/d). Osmosis itself is the diffusion of water across the cellular membrane in and out of a cell. The direction of net movement is decided by the concentration of water and solutes on either side of the cell, always moving towards the side with the lesser concentration of water (Nave, n/d). The concentration is solutes is called the Tonicity, and this dictates the movement of osmosis across a membrane (Kahn Academy, n/d). To test this relation, potato cores were placed in different solutions with varying levels of sucrose and water. The common conception was that the increase in sucrose within a solution will cause osmosis to occur to a lesser extent between the potato and the solution. To measure this, the potatoes were weighted after a night of soaking in the solutions to test for a change in weight. It was the general conception that the greater the amount of sucrose within the solution, the lighter the potato will be.

Review Sheet Results 1. Explain one way in which facilitated diffusion is the same as simple diffusion and one way in which it is different from simple diffusion. Your answer: Simple diffussion moves molecules from an area of higher concentration to lower without an input of energy. facilitated follows the same rule but uses protein carrier molecules to allow substance that are fat solubles to diffuse through the cell membrane. 2. The larger value obtained when more glucose carriers were present corresponds to an increase in the rate of glucose transport. Explain why the rate increased. How well did the results compare with your prediction? Your answer: My prediction was wrong the glucose transport rate would increase 3. Explain your prediction for the effect Na+ Cl- might have on glucose transport. In other words, explain why you picked the choice that you did. How well did the results compare with your prediction? Your

Activity 3: Osmosis Osmosis is a specific type of diffusion. It is the movement of water molecules from an area of high water concentration to an area of low water concentration. Semipermeable membranes, such as the cell membrane, allow the unrestricted movement of water across the membrane, at the same time restricting the movement of solute molecules and ions. It has been estimated that an amount of water roughly equivalent to 250 times the volume of the cell diffuses across the red blood cell membrane every second. Despite this large movement of water molecules, the cell does not lose or gain water, because equal amounts go in and out.

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.