Microscope and Cell Structure and Function- Virtual PDF

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Assignment related to week 1 of human biology laboratory (BSC 2023L) for the summer term....

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Microscope and Cell Structure & Function Lab Learning Objectives: Students should be able to: 2.1 Use of the Compound Light Microscope  Name and give the function of the basic parts of the compound light microscope.  List, in proper order, the steps used for bringing an object into focus with the compound light microscope.  Calculate the total magnification.  Describe how the slide of the letter e provides information on the inversion of the image in the compound light microscope. 2.2 Use of the Dissecting Microscope  Name and describe the function of the basic parts of the dissecting microscope.  Learn how to use the dissecting microscope. 2.3 Microscopic Observations  State two differences between onion epidermal cells and human epithelial cells.  Identify plasma membrane/cell wall, nucleus and cytoplasm. 2.4 Human (Animal) cell structure  Identify the structures of a human (animal) cell.  Identify and state the functions of the organelles of an animal cell. 2.5 The plasma membrane  Define and describe the process of diffusion as exemplified by the experimental procedure used here.  Define isotonic, hypertonic and hypotonic solutions and give examples in terms of solute concentration.  Predict the effect of these solutions on red blood cells.

Task 1: Microscopy- Compound Light Microscope 1. Microscope: Familiarize yourself with the parts of the light microscope using the lab manual (pgs. 19-26) and the PowerPoint provided. Label the microscope in the assignment on Canvas, and answer the questions in the assignment. 2. Total magnification = the magnification of the ocular lens X the magnification of the objective lens. Complete The Total Magnification Table. Show your work below:

Objective Scanning power Lower power High power Oil immersion

Ocular Lens 10x 10x 10x 10x

Objective Lens 4x 10x 40x 100x

Total Magnification 40x 100x 400x 1000x

3. Microscope use a. Read “Rules for Microscope Use” (pg. 21). b. Familiarize yourself with focusing the microscope (pg. 21-22). 1. Which focusing knob is used for each of the objectives? Mechanical stage control knobs are two nobs that control forward/reverse movement. Course-adjustment knob is used to bring object into approximation focus, is used only with low-power objectives. Fine-adjustment knob: is used to bring object into final focus. 4. Review “Observation: Inversion” (pg. 22) Draw the letter “e” from the slide as you can see it with the naked eye. Then, following instructions of your Lab Instructor, how does the letter "e" appear through the microscope? Use the PowerPoint to help you through this. 1. Naked eye 2. Looking through ocular lens

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Move the slide to the right. Where does the letter appear to move? Appears upside down and backwards (inverted) as you look through the lenses . Why does this happen? Its caused by the objective lens being curved causing light to crossover before it goes through the ocular lens and gets to your eyes . What is the name of this property? inversion .

New Instrument: Plastic Transfer Pipette. These pipettes are used to transfer liquids, usually without precise measurement. They may be available graduated, and not graduated. Graduated pipettes can measure 0.5mL and 1mL. These pipettes can also be used to add drops of liquid to containers.

5. Read "Human Epithelial Cells" (pg. 26).

You will view slides of "Human Epithelial Cells,” virtually on the PowerPoint provided by your lab instructor. Draw a diagram of human and plant cells, indicating the nucleus, cytoplasm and cell membrane and/or cell wall.

Task 2: Microscopy- Dissecting Microscope 1. Microscope: Familiarize yourself with the parts of the dissecting microscope using the lab manual (pgs. 17-19) and the information in your PowerPoint. Pertinent questions will be available through your Canvas assignment. 2. Which microscope should be used to view microscopic organisms? Compound microscope . 5. Which microscope should be used to view macroscopic organisms? Dissecting microscope . List 5 organisms that you would be able to see under the dissecting microscope. Butterflies, ants, flowers, fossils, and leaves.

Task 3: Cell Structure. Identify and learn the functions of the organelles in human (animal) cells (pgs 45-47). Organelle Nucleus Cytoplasm Mitochondria Ribosomes Golgi Apparatus Lysosome Endoplasmic Reticulum

Function In plant and animal cells; controls many functions of the cells. Located in animal and plant cells; a jellylike material located inside the cell where all the organelles are located. Organelle where cellular respiration occurs, and most ATP is generated. Complexes that synthesize proteins. Located in animal and plant cells; an organelle that packages and moves proteins out of the cell. Located in animal and plant cells; a spherical organelle where the digestion of cell nutrients takes place. Located in animal and plant cells; an organelle that transports materials throughout the cell. The rough ER has ribosomes attached to it, the smooth ER does not.

Task 4. Diffusion Demonstration. Based on the PowerPoint presented, the following procedure on page 58 is depicted. 1. Diffusion through a semi-solid and diffusion through a liquid. Use the demonstration to answer the following questions: a. Where does diffusion occur more quickly? Semi-solid . b. Why? Particles move slower in a fluid . New Chemical: Agar. Agar is a semi-solid, gel-like substance. It is usually used as a growth surface in microbiology. It can be mixed with different growth media (i.e. Luria Broth), antibiotics/medicines (i.e. ampicillin) to grow bacteria (i.e. E. coli). New Chemical: Potassium permanganate (KMnO4) . KMnO4 is a strong oxidizing agent. It should not be handled with bare skin. Anyone handling this chemical should be wearing gloves and should use tweezers to add KMnO4 pieces to the containers.

Task 5. Osmosis and Tonicity Demonstration. 1. Learn about Osmosis and Tonicity in your lab manual on pages 51-53. Based on the PowerPoint, the following experiments are depicted. (Pages 52-53) 2. A potato piece will be placed in a hypotonic solution (water), hypertonic solution (10 % NaCl) and an isotonic solution (0.9% NaCl). Use the demonstration and the lab instructor’s explanations to answer the following questions: What happens to the potato in a hypotonic solution? Expands/ bursts . What happens to the potato in a hypertonic solution? shrivels . What happens to the potato in an isotonic solution? Normal, no gain or loss . 3. Tonicity in red blood cells. - Hypotonic Solution (5mL of distilled water) + 5 drops of sheep’s blood - Hypertonic Solution (5mL of a10 % NaCl solution) + 5 drops of sheep’s blood - Isotonic Solution (5mL of a 0.9% NaCl solution) + 5 drops of sheep’s blood -

Which tube allows you to read through it? Stoppered test tube . Why? Its transparent . - Why is the isotonic solution a 0.9% NaCl solution, and not the distilled water? The concentration of the water inside and outside the cell is equal and there is no net water movement across the cell membrane. . Lab Safety: Wear gloves and goggles. Since you are working with a solution of sheep’s blood, you should wear gloves before handling a pipette and slide with blood, and you should wear goggles in case of any splash.

4. On your PowerPoint, there are pictures of red blood cells with each of the following solutions added, under the compound light microscope. Draw your observations in the spaces below.

***If you were in an in-person lab: Before you leave, you would make sure your table and instruments are CLEAN and that you placed the microscopes away in the cabinet, properly, with the lowest power objective lens in place. You would make sure to follow your lab instructor’s directions as to where to dispose of used materials....