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Questions and Answers
What is the expected effect on red blood cells placed in a hypotonic solution?
What is the expected effect on red blood cells placed in a hypotonic solution?
Which component of the red blood cell is responsible for oxygen transport?
Which component of the red blood cell is responsible for oxygen transport?
What characteristic of mature red blood cells distinguishes them from immature ones?
What characteristic of mature red blood cells distinguishes them from immature ones?
What should be avoided when covering the slide with a coverslip during the procedures?
What should be avoided when covering the slide with a coverslip during the procedures?
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How many red blood cells are typically found per microliter of blood?
How many red blood cells are typically found per microliter of blood?
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What happens to red blood cells in a hypertonic solution?
What happens to red blood cells in a hypertonic solution?
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What arrangement of cells should be created during the onion cell observation?
What arrangement of cells should be created during the onion cell observation?
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What should be labeled on the slides after observing the onion plant cells?
What should be labeled on the slides after observing the onion plant cells?
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What effect does a hypertonic solution have on plant cells?
What effect does a hypertonic solution have on plant cells?
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Which of the following correctly describes diffusion?
Which of the following correctly describes diffusion?
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In which situation will a plant cell become flaccid?
In which situation will a plant cell become flaccid?
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What is the significance of selectively permeable membranes in cells?
What is the significance of selectively permeable membranes in cells?
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What should be done if glass slides and cover slips are used?
What should be done if glass slides and cover slips are used?
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Which description best fits a hypotonic environment for plant cells?
Which description best fits a hypotonic environment for plant cells?
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What is the primary objective of the experiment involving onion plant cells?
What is the primary objective of the experiment involving onion plant cells?
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How should a scalpel be handled during experiments?
How should a scalpel be handled during experiments?
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Study Notes
Laboratory Exercise 1: Membrane Permeability
- Course: Molecular and Cellular Biology (MD105)
- Semester: Fall 2024
- Instructors: TC. Kyriakou & D. Markantoni
- Topic: Membrane permeability of onion plant cells and human red blood cells
- Safety Procedures: Students must arrive on time to avoid overcrowding, wear lab coats with cuffed sleeves, masks, and safety goggles, wash hands with soap and put on gloves, disinfect work surfaces before and after experimentation, and report any symptoms immediately.
- Absences: Mandatory physical presence or synchronous participation. Only two justified absences are permitted (severe health conditions or emergencies). Justified absences must be announced before class begins. Lab experiments cannot be repeated.
- Preparation: Students are expected to study uploaded material and print out protocols or experimental methodolgies. Review materials/equipment to be used in protocol. Be prepared for technically demanding applications. Closed-toe shoes, lab coat, goggles, and gloves are required. Hair must be tied up in a ponytail. Food and drinks are not allowed in the lab.
- Laboratory Notebook: Maintain a detailed laboratory notebook. Record everything explained, protocol applications (date-stamp each entry), reagent concentration calculations (e.g., C1V1 = C2V2), and evaluate results, noting any necessary adjustments.
- Lab Etiquette: Move around as if in a bubble, know your surroundings, work as a team, respectfully avoid fast movements, raise your hand to ask questions, and work silently.
- Contact Information: Inquiries, clarifications, and other issues should be addressed to the appropriate faculty email or office. Emails sent to faculty members from personal accounts must be forwarded through the official university email account.
Objectives
- Observe the effect of different solutes on diffusion of plant and human cells.
- Explain hypertonic, hypotonic, and isotonic solutions in terms of cellular environments.
- Compare and assess cell transport activity in human and plant cells.
Safety Precautions
- Do not eat or drink in the laboratory.
- Wear safety glasses, lab coats and gloves while performing experiments.
- Handle scalpels carefully; they are sharp.
- Hold scalpels like pencils and cut in a downward motion, avoiding excessive pressure.
- Keep your hand responsible for specimen placement in mind and avoid cutting with that hand.
- Do not use equipment for any task other than its intended purpose.
- Exercise care with glass slides and cover slips.
Diffusion
- Living organisms require material movement (e.g., nutrients, water, waste) into and out of cells for survival.
- This movement maintains homeostasis.
- The membranes surrounding organelles and the plasma membrane regulate material transport.
- These membranes are selectively permeable.
- Cellular environments are typically aqueous.
- Solutes (e.g., salts, organic molecules) are dissolved in water and are necessary for cell function.
- Diffusion is the simplest method for molecules to move from high to low concentration.
- This process requires no energy.
Osmosis
- Osmosis is a specific type of diffusion dealing with water movement across a selectively permeable membrane. The difference between osmosis and diffusion is that osmosis focuses specifically on water movement.
- Water moves from a higher water concentration to a lower water concentration.
Onion Plant Cells
- A plant cell's reaction to a solution depends on the solution's water concentration relative to the cell's interior.
- Hypotonic environments cause water to enter the cell and make the plant cell firm (turgid)
- Hypertonic environments cause water to leave the cell and make the plant cell soft (flaccid).
- Isotonic solutions maintain equilibrium. Water movement in and out are balanced.
Experimental Procedure - Part A: Onion Plant Cells
- Collect materials & take them to work area.
- Peel and prepare onion tissue.
- Place onion tissue on a dry microscope slide, shiny side up.
- Add Solution A to the tissue. Use a drop of Solution A.
- Cover with coverslip and carefully remove any air bubbles
- Repeat steps using solutions B & C.
- Observe under a microscope (low and high magnification).
- Label cell parts (cell wall, cytoplasm, nucleus).
- Take pictures.
- Compare slide A, B, & C and determine the solutions used.
Red Blood Cells
- Red blood cells (erythrocytes) are biconcave.
- Erythrocytes are produced in bone marrow, mature in bloodstream.
- Erythrocytes transport oxygen from lungs to tissues.
- Erythrocytes contain hemoglobin, a protein that carries oxygen.
- Erythrocytes are anucleate (they have no nucleus).
- Mature erythrocytes cannot divide or replicate.
- There are 4-6 million per microliter of blood.
- Hypertonic solutions cause red blood cells to shrink (crenate).
- Hypotonic solutions cause red blood cells to swell and potentially burst (lyse).
- Isotonic solutions maintain normal cell shape.
Experimental Procedure - Part B: Red Blood Cells
- Place a drop of blood on a clean slide.
- Label the slide (group and solution).
- Add Solution A and cover with coverslip (avoid air bubbles), then repeat with solutions B &C.
- Observe under a microscope (low and high magnification).
- Label cellular parts (cytoplasm, membrane).
- Take pictures and compare the three slides to determine which slide corresponds with Solution A, B, C.
Questions
- Questions about the procedures, results and analyses of experiment are provided.
Additional Information
- Images of onion and red blood cells under magnification (microscope images) are provided.
- Solutions A, B, and C are referenced within the procedures sections
- Concepts like hypertonic, hypotonic, and isotonic are explained in the context of cellular responses to different solutions.
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Description
This quiz focuses on the laboratory exercise about membrane permeability in onion plant cells and human red blood cells. Students will assess safety procedures, preparation requirements, and experimental methodologies to ensure a thorough understanding of cell membrane properties.
