* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Diffusion and Cell Membranes
Survey
Document related concepts
Membrane potential wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Cell encapsulation wikipedia , lookup
Signal transduction wikipedia , lookup
Cell growth wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Diffusion and Cell Membranes Skills • modeling a cell with a cell membrane • observing the process of diffusion through a cell membrane • predicting the direction of diffusion • measuring the mass of an egg Objectives : • Explain changes that occur in a cell as a result of diffusion. • Distinguish between hypertonic and hypotonic solutions. Purpose: In this lab, you will use eggs with a dissolved shell as a model for a living cell. You will then predict the results of an experiment that involves the movement of water through a membrane. Background: Some chemicals can pass through the cell membrane, but others cannot. Not all chemicals can pass through a cell membrane with equal ease. The cell membrane determines which chemicals can diffuse into or out of a cell. As chemicals pass into and out of a cell, they move from areas of high concentration to areas of low concentration. Cells in hypertonic solutions have solute concentrations lower than the solution that bathes them. This concentration difference causes water to move out of the cell into the solution. Cells in hypotonic solutions have solute concentrations greater than the solution that bathes them. This concentration difference causes water to move from the solution into the cell. The movement of water into and out of a cell through the cell membrane is called osmosis. Predictions: Predict how the mass of each egg will change after 24 hours in each liquid. (HINT: An egg is surrounded by a membrane. Inside the membrane, the egg white consists mainly of water and dissolved protein. The yolk consists mainly of fat and water. Syrup is sugar dissolved in water. The protein, fat, and sugar are solutes.) Record your predictions in the data table 1. After 24 hours, observe your eggs and record your observations and measurements. What will have occurred if your egg gains or loses mass? Table 1: Egg Observations Egg Liquid environment 1 2 3 Predicted Change after 24 hr Observations after 24 hr Table 2: Mass Differences of Eggs in Different Solute concentrations. Mass Percent Change in Mass* Egg Initial Mass Final Mass Difference (show work) 1 2 3 *To calculate Percent Change in Mass: Final Mass – Initial Mass x 100 Initial Mass Analysis and Conclusions: 1. What effect did the vinegar have on the eggs? 2. What caused the change in appearance in Egg 1 after it soaked in water? 3. Why did the mass of the egg increase after soaking in the vinegar solution? 4. What material seems to have moved through the membrane of Egg 2 after it was soaked in the syrup? In what direction did it move? 5. Which egg was in a hypertonic solution? Explain. 6. Which egg was in a hypotonic solution? Explain.