Module 1 Lab A^0P

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Metropolitan Community College, Kansas City *

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MISC

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Biology

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Jan 9, 2024

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Part 1: The Microscope This exercise is meant to teach you how to use the microscopes properly. Learning how to use a microscope efficiently is not easy. It takes time and patience!! As you go through the following exercises you should gain experience and skills that will help you throughout the semester. Every time you use the microscopes remember to clean the oculars, close down the diaphragm by moving the lever to the right, and start with the lowest power objective. A. Basic care and use of the microscope. 1. Obtain a microscope. Carry the microscope by the arm and the base. Use two hands and do not try to carry anything else at the same time. 2. Obtain a few sheets of lens paper and a bottle of lens cleaner (two bottles per bench is fine). 3. Plug in your microscope and use Figure 1 to become familiar with the parts of the microscope. 4. Turn on the light and rotate the nosepiece until the 4X objective is pointing down. Clean the oculars with lens paper moistened with lens cleaner. 5. Obtain a slide of skeletal (striated) muscle tissue . Clean the slide (both sides) with lens paper by rubbing the slide between your thumb and index finger. Place the slide on the stage. Use the lever to open and close the clip that holds the slide in place. 6. Use the mechanical stage control knobs to move the slide and position the slide directly below the 4X objective. 7. Look through the oculars. You may need to adjust the amount of space between the oculars - gently pull them apart or push together until you can see through both. Most microscopes have diopter adjustments for one or both oculars. Begin use with no adjustment (set both oculars to the same setting or no adjustment). Make adjustments as needed, if you have difficulty focusing both eyes on the slide in the next step. 8. Use the coarse adjustment knob to bring the slide into focus. You should see dark red cells that are long and skinny and run parallel to each other. You may need to move the slide up or down to find the cells. If you do not see the cells, notify the instructor. 9. Rotate the nosepiece until the 10X objective clicks into place. Use the fine adjustment knob to bring the muscle cells into focus. 10. Rotate the nosepiece until the 40X objective is in place. Use the fine adjustment knob to bring the cells into focus. Notice how close the objective is to the slide. This is the reason for using the fine adjustment knob when working with the 40X or higher objectives. 11. Rotate the nosepiece until the 4X objective is in place and remove the muscle tissue slide. 1

B. Orientation of the image. Obtain a slide with the letter e mounted on the surface. Place the slide on the stage and bring the e into focus. 1. Compare the orientation of the e on the slide to the image of the e that you see through the microscope. How is it different? The image of e on the slide is upside down compared to how it looks through the oculars. 2. Use the control knobs to move the slide to the right while watching through the microscope. In which direction does the image move? The image moves left. Questions: 1. Why should we never use the coarse adjustment knob with anything but the low (4X) power objective? It adjusts the stage too much, too quickly. It makes it MUCH harder to find your specimen again. 2. What are the two things we have to do to make sure the image we have found under low power is still visible when we switch to medium or high power? If it is center and if it is in focus. E. Practice 1 . Obtain a slide of intestine . Start at 4X power. Work your way up to 40X. Find the center of the intestine where you are able to see open air space and focus on the cells lining the intestine. This is the epithelial layer. Move the slide to focus on the cells that wrap around the intestine. This is smooth muscle. 2 . Obtain a slide of skin . Find cells lining the surface. You will be able to see hair emerging through the surface. Scan down below the surface layer and look for different types of cells. Think of the functions of the different types of cells. 3. Obtain a slide of lung tissue . Look around on the slide at different magnifications. (Always start at 4X power.) You will see open air space between very thin cells, and you will also see blood vessels and bronchioles and maybe some cartilage. F. Clean up. 1. Lower the stage. Rotate the 4X objective into place. Use moistened lens paper to clean the oculars. Turn off the light switch and unplug the microscope. 2. Fold/secure the cord in a way appropriate for the microscope, under the stage, around attached bracket, or under the plug-in power supply. Carry the microscope back to the cabinet. Check the number on the microscope and place it in the corresponding location in the cabinet. 2

Objective X Ocular = Total Magnification 4x X 10x = 40x 10x X 10x = 100x 40x X 10x = 400x 100x X 10x = 1000x 3

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Part 2: Cellular Metabolism Directions: Complete the following Virtual Labs in McGraw-Hill Connect and record your observations in the space provided . A. Scientific Method* The pill bugs were attracted to the cornstarch. All ten of the insects ended on the side with the cornstarch. B. Chemical Composition of Cells – Test for Proteins Pepsin and Albumin both turned purple or pink, meaning they had proteins in them. The pepsin was the darker of the two, and thus had more proteins. C. DNA – Gel Electrophoresis The DNA underwent four different types of mutations. The first mutation was missense: substitution and affected one amino acid. The second was frameshift: insertion and affected 3. The third was nonsense: substitution and affected two. The final was a silent substitution and affected no amino acids. D. Enzyme Function – Effect of pH The reaction rate is fastest near an even 7 pH. If the mixture is too basic or too acidic, it will have a slow reaction rate. Part 3: Cell Division - Mitosis Mitosis Mitosis is the division of one cell into two daughter cells. The daughter cells have the same number of chromosomes as the original cells. Mitosis is necessary for growth, repair and replacement of your cells. Prior to mitosis a cell duplicates its chromosomes and organelles during interphase. Mitosis begins when a cell enters prophase. A. Models 4

Look at the models depicting the 4 major stages of mitosis. Determine the order in which these events occur and describe them below. 1. Prophase – The chromosomes condense and become visible, nuclear envelope breaks down. Spindle fibers develop. 2. Metaphase – The chromosome pairs line up in the middle of the cell, spindle fibers grab on. 3. Anaphase – Sister chromatids are pulled apart by the spindle fibers. 4. Telophase – The nuclear envelopes reform as cytokinesis takes place, fully cleaving one cell into two. B. Cells in different stages of mitosis. 1. Obtain a slide of onion root tip or whitefish blastula. 2. Find an area of the slide that contains many cells in stages of mitosis. Move up to the 10X then 40X objectives. You should be able to see cells and the chromosomes in some of the cells. 3. Locate cells that are in interphase. Write a description of the cells and include some cells in interphase in your drawing below (insert picture). Some of the cells have grown larger with visible chromatin. 4. Locate cells in all of the stages of mitosis. 5

Part 4: Histology A tissue is a collection of cells that are structurally and functionally similar. Humans have four major types of tissues. 1. Epithelial tissues lines body cavities or make up the external surface. 2. Connective tissues are involved in binding and support. 3. Muscle tissues are involved in movement. 4. Nervous tissue is involved in communication. Microscope use 1. Be very careful with the microscopes!!! 2. Always use properly. Do not hurry. 3. Use lens paper, only, to clean slides, and oculars should only be cleaned with moistened lens paper. 4. Always begin with the smallest objective (4X), and then proceed to the 10X objective. You should use ONLY the fine adjustment knob after you have initially focused the 4X objective. Epithelial Tissue Obtain the following slides. Clean them with lens paper and place the first one on the microscope stage. Use the 4X objective to bring the image into focus. Use the 10X objective and the fine adjustment knob to bring the image into focus again. You may want to use the 40X objective to get a closer look at some of the slides. DO NOT use 100x unless specified. Insert pictures of the epithelial tissues as you look at them. Are you in the right area of the slide?? Check with your instructor if you are not certain. Simple squamous Simple cuboidal Simple columnar --lung --kidney --fundic stomach or intestine 6

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0 Stratified squamous Transitional Pseudostratified --esophagus --bladder (some slides) ciliated columnar 1. Why have simple epithelial tissue in some areas and stratified in others? 2. What is the function of the cilia? Can you guess where you might find pseudostratified ciliated columnar epithelia? Connective Tissue Areolar Adipose Dense Regular Dense Irregular --tendon --dermis of skin 7

Hyaline Cartilage Elastic Cartilage Bone Blood 1. How are the structures of dense regular and dense irregular connective tissues related to their functions? 2. Can you identify any similarities between bone, blood and cartilage? 3. Where would you find Hyaline cartilage? Muscle Tissue Cardiac Skeletal Smooth Where would you find the different types of muscle? Cardiac- 8

Skeletal- Smooth- Nervous Tissue Neurons (spinal cord) What is the function of nervous tissue? Conclusion 1. Now that you have looked at many different types of tissues, look at a slide of skin again. Find the epidermis and look below the dermis. What type of tissue do you see? 2. Move through different areas of the slide. Can you find blood vessels with red and white blood cells within? 3. Do the same thing with a slide of the trachea, possibly labeled pseudostratified ciliated columnar epithelium . Again, look below the epithelial layer to the tissues below. You should be able to recognize and distinguish between the different types of tissues. Obtain a microscope and slide of skin (normal skin, not skin cancer). Look at the slide under low power. You will be able to see hair follicles extending out from the skin tissue. Go up to the 10X or 40X to look at the epidermis layer. It is not very thick and stains purple. It will also be flaking off at the top. 1. What type of tissue makes up the epidermis? 9

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2. Look at the dermis layer. Can you find a gland? You may not be able to see any on your slide, but try to find one using the photos in your text as a guide. You may also find blood vessels as well. 3. What type of tissue makes up the dermis? 10

Module 1 Lab A^0P

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