Membrane Permeability
Experiment 5
Title: Membrane Permeability
Objectives:
1. Define solvent, solute, solution, selectively permeable, diffusion, osmosis, concentration gradient, equilibrium, turgid, plasmolyzed, plasmolysis, turgor pressure, tonicity, hypertonic, isotonic, hypotonic;
2. Describe the effects of hypertonic, isotonic, and hypotonic solutions on Elodea leaf cells and onion scale leafs.
Introduction:
Membrane permeability is a quality of a cell’s plasma membrane that allows substances to pass in and out of the cell, so that the cell can expel waste products and ship out the chemicals it assembles for the body. At the same time, the nutrients that the cell needs can pass through the membrane to the inside. Cell membranes have selective permeability, meaning that the membrane will allow certain substances to pass while forming a barrier against others.
Cells are like microscopic factories: they design, produce, and package the substances the body needs to survive each day. Just like a factory, a cell needs a way to bring the raw materials for its products — such as nutrients from food — inside its workshop. Once the cell has assembled and packaged a substance, the cell needs a way to ship the finished product out into the bloodstream so that the body can make use of it.
The cell membrane is a flexible plasma that envelopes the exterior boundaries of the cell. It separates the intracellular fluid — the fluid within the cells — from the extracellular fluid, which is the fluid outside of the cells. The cell membrane is not a passive or insurmountable wall however, as there is a constant and dynamic exchange of substances between the two fluids.
If a plant cell is placed in a hypertonic solution, the plant cell loses water and hence turgor pressure, making the plant cell flaccid. Plants with cells in this condition wilt. Further water loss causes plasmolysis: pressure decreases to the point where the protoplasm of the cell peels away from the cell wall, leaving gaps
Title: Membrane Permeability
Objectives:
1. Define solvent, solute, solution, selectively permeable, diffusion, osmosis, concentration gradient, equilibrium, turgid, plasmolyzed, plasmolysis, turgor pressure, tonicity, hypertonic, isotonic, hypotonic;
2. Describe the effects of hypertonic, isotonic, and hypotonic solutions on Elodea leaf cells and onion scale leafs.
Introduction:
Membrane permeability is a quality of a cell’s plasma membrane that allows substances to pass in and out of the cell, so that the cell can expel waste products and ship out the chemicals it assembles for the body. At the same time, the nutrients that the cell needs can pass through the membrane to the inside. Cell membranes have selective permeability, meaning that the membrane will allow certain substances to pass while forming a barrier against others.
Cells are like microscopic factories: they design, produce, and package the substances the body needs to survive each day. Just like a factory, a cell needs a way to bring the raw materials for its products — such as nutrients from food — inside its workshop. Once the cell has assembled and packaged a substance, the cell needs a way to ship the finished product out into the bloodstream so that the body can make use of it.
The cell membrane is a flexible plasma that envelopes the exterior boundaries of the cell. It separates the intracellular fluid — the fluid within the cells — from the extracellular fluid, which is the fluid outside of the cells. The cell membrane is not a passive or insurmountable wall however, as there is a constant and dynamic exchange of substances between the two fluids.
If a plant cell is placed in a hypertonic solution, the plant cell loses water and hence turgor pressure, making the plant cell flaccid. Plants with cells in this condition wilt. Further water loss causes plasmolysis: pressure decreases to the point where the protoplasm of the cell peels away from the cell wall, leaving gaps