MD105 Cellular and Molecular Biology Lab Exercise #1 PDF

Kyriakou.TC/Markantoni D/Andreou M. F2024 MD105 Cellular and Molecular Biology Lab Exercise #1: Membrane Permeability of Onion Plant Cell and Human Red Blood Cells Introduction Passive transport is a way to move ions and other molecular s...

Kyriakou.TC/Markantoni D/Andreou M. F2024 MD105 Cellular and Molecular Biology Lab Exercise #1: Membrane Permeability of Onion Plant Cell and Human Red Blood Cells Introduction Passive transport is a way to move ions and other molecular substances across membranes, without the use of energy. In all living organisms, there is a basic functional unit. This is the cell. Within the cell, there are cell organelles and the nucleus which are surrounded by a membrane. The cell membrane functions in separating the external environment from the interior of the cell. It is made up of a phospholipid layer within which proteins are embedded and among its many properties, it is selectively permeable to what enters or leaves the cell. Transport occurs to balance the concentrations inside and out to reach an equilibrium. Passive transport can be divided into diffusion, facilitated diffusion and osmosis. Osmosis is the movement of water molecules through a semi-permeable membrane from a solution of higher concentration of water to a solution with lower concentration of water. This phenomenon can be observed under the microscope in living cells. In comparing two solutions of unequal solute concentration, the solution with higher solute concentration is called hypertonic, and the solution with the lower solute concentration is called hypotonic. Solutions of equal solute concentration are isotonic. Objectives: 1. To observe different cell types under the microscope at low and high magnification and describe any differences. 2. To test the rate of penetration and diffusion of various solutions (hypertonic and hypotonic). 1  Kyriakou.TC/Markantoni D/Andreou M. F2024 Osmosis in onion plant cells Effects of hypertonic, isotonic, and hypotonic solutions on plant cells Osmosis in human red blood cells: Effects of hypertonic, isotonic, and hypotonic solutions on plant cells 2  Kyriakou.TC/Markantoni D/Andreou M. F2024 A red blood cell will swell and undergo _________ when placed in a hypotonic solution. When placed in a hypertonic solution, a red blood cell will _______ and undergo ___________. EXPERIMENTAL PROCEDURE Materials/Equipment: 1. Pipetman (P1000, P200, P10) 2. Pipette tips 3. Scissors 4. Forceps 5. Microscope slides 6. Cover slips 7. Microscope 8. Fresh onion 9. Human red blood cells 10. Hanks Buffer/Blue Stain 11. Distilled Water/Blue Stain 12. 1.8% NaCl/Blue Stain 13. Waste container 14. Camera to capture microscope images of the cells PART A: Onion plant cell Collect all your materials and take them to your work area. 1. Peel your onion. 2. Place the onion tissue layer on a dry microscope slide with the shiny side facing up. 3. Do not forget to label the slide (group and solution). 4. Add a small drop of solution A directly to the tissue. 5. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip. 6. Repeat steps 1-3. 7. Add a small drop of solution B directly to the tissue. 8. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip 9. Repeat steps 1-3. 10. Add a small drop of solution C directly to the tissue. 3  Kyriakou.TC/Markantoni D/Andreou M. F2024 11. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip. You must have three slides! 12. Observe the prepared mount of the peel under the low and high magnification of a microscope. 13. Label the parts you see (cell wall, cytoplasm, nucleus) and take pictures (one for each slide). 14. Compare the three slides and decide as a group which slide has solution A, B, and C. A B C 1. Which slide has Hypertonic, Hypotonic, and Isotonic solutions? Why? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 4  Kyriakou.TC/Markantoni D/Andreou M. F2024 PART B: Human Red Blood Cells 1. Add a small drop of blood onto a clean slide. 2. Do not forget to label the slide (group and solution). 3. Add a small drop of solution A directly to the drop. 4. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip. 5. Repeat steps 1-3. 6. Add a small drop of solution B directly to the drop. 7. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip. 8. Repeat steps 1-3. 9. Add a small drop of solution C directly to the drop. 10. Carefully cover it with a coverslip and avoid any air bubble from entering the coverslip. 11. You must have three slides ! 12. Observe the blood drops under the low and high magnification of a microscope. 13. Label the parts you see (cytoplasm and membrane) and take pictures (one for each slide). 14. Compare the three slides and decide as a group which slide has solution A, B, and C. 2. Which slide has Hypertonic, Hypotonic, and Isotonic solutions? Why? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 5  Kyriakou.TC/Markantoni D/Andreou M. F2024 Additional Questions: 1. What differences did you observe between human cells versus a plant cell? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. Define osmosis and facilitated diffusion and explain the difference from active transport. ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ 6