BIOL-112_Lab 1Microscope & Cells JZ

BIOL-112: Lab 1 – Microscope & Cells The Microscope Part 1: The Microscope Anatomy 1. Label the parts of the Microscope shown in the picture below. (Image modified from https://www.amscope.com/) 1. eye piece 8. power switch 2. nose piece 9. light intensity knob 3. objective lens 10. stage adjustments knob 4. stage 11. fine focus adjustments knob 5. diaphragm 12. coarse focus adjustment knob 6. light source 13. arm 7. base 14. rotating head Part 2 : How to Use and Focus Your Microscope:

BIOL-112: Lab 1 – Microscope & Cells Access the following link and follow the instructions below to practice using the microscope with everything you just learned in this section:  Virtual Microscope Experiment 1. Turn on the light on the microscope and set it up to 10 2. Select the slide with the letter “e” . 3. Place the 4X objective lens 4. Center and position your specimen by using the stage controls 5. Switch views at this point 6. Adjust the ocular lens 7. Locate your specimen using the coarse adjustment knob. 8. Adjust the iris diaphragm 9. Center your image and move to the next objective lens (10X). 10. Use the fine adjustment knob to adjust the focus. 11. Move to the high-power lens (40X) and use the fine adjustment knob and the iris diaphragm as needed. 12. Repeat using the onion root tip and cheek cells slides. Watch the videos about how to use a microscope, provided in this module. Answer the following questions after you are done practicing: 1. What is the first step you must complete in order to observe a specimen? First step is to place a glass cover on the specimen. 2. Why do we must always start with the 4X objective lens? What is its function? We use the 4x objective lens because it’s the lowest magnification, and by starting with the lowest magnification, we can spot and focus on the specimen. 3. What happens when you move the slide to the left? What happens when you move it to the right? What happens when you move the slide to up? What happens when you move it down? Why does this happens? When the slide moves left, the image will move right, and if the slide is moved right, the image will move left. If the slide moves up, the image moves down, and if the slide moves down, the image will move up. 4. Why do we adjust the iris diaphragm? What will be the result of doing so? We adjust the iris diaphragm to control the amount of light that is exposed on the specimen. The result is we see the specimen better. 5. Why do you have to adjust the focus using the fine adjustment knob when moving higher in objective lens? Why do you had to adjust the iris diaphragm as well? When moving higher in the objective lens, you must adjust the focus because the specimen will not be shown correctly. You must also adjust the diaphragm because the light needs to be readjusted.

BIOL-112: Lab 1 – Microscope & Cells # of ruler lines: ____5 mm ____2.5 mm ___0.5 mm  What is the relationship that exists between magnification and field of view? As the magnification increases, the field of view decreases.  In other words, a specimen is viewed through a microscope under high magnification. The image will have a_______ narrow ______________ (narrow/wide) field of view. Next, you noticed that the distance from the end of the objective lens to the slide when it is in focus, also known as the working distance , changed with each objective lens. In the next experiment, you measured the working distance for each magnification and obtained the following results: 4X = 25 mm 10X = 8.5 mm 100 X = 0.5 mm  What is the relationship that exists between magnification and working distance? When increasing the magnification, you must move closer to the specimen. Finally, you are about to observe a slide with crossed color threads under the microscope to better understand the concept of the depth of field , which refers to the thickness of the specimen that is in focus at any one time. You noticed that at 4X, you are able to see the three threads as a sharp image. However, when you move to use the 10X objective lens, you can only see 2 in focus, and when you move to the 40X objective lens, you can now only see one thread in focus. Click on the link here to observe the video of the experiment  Depth of Field Experiment  What can you conclude about from these results? o Does all objective lenses have the same depth of field? Why yes or why not? No, not all objective lenses have the same depth of field because, once the magnification increases, the depth of focus also decreases.  What is the relationship that exists between magnification and depth of field? When magnification increases, the depth of field decreases. Use the following table to summarize your results from this part: Objective Magnification: Total Magnification Diameter of Field Working Distance Depth of Field 4x 40x 5 8 3 10x 100x 2 3 2 40x 400x 1 1 1 As magnification increases… Magnification increases by 10x Diameter decreases Working distance becomes shorter The depth of field decreases (Image modified from https://www.biologycorner.com/)

BIOL-112: Lab 1 – Microscope & Cells Part 4 : Wet Mount As a General Biology student you need to create a Wet Mount to look at the living microorganisms in the pond sample you obtained from a field trip. Before starting to make your wet mount, you review the steps. Using the figure presented here, what are the steps you must follow for making a wet mount? A. Place the specimen on the slide. B. Place the coverslip carefully on the specimen. C. Make sure the cover slip is on and clean around the edges. Click on the link to see learn how to prepare a wet mount slide in more detail  Wet Mount Technique Answer the following questions:  Why do you need to mix well the sample before putting it on the slide? You need to mix the sample to get microorganisms on the slide.  Why do we always need to cover the sample with a cover slip? we need to cover the sample so the specimen won’t slide off.  What would happen if you place the cover slip too fast? How would that affect your observations? If you place the cover slip too fast, it might break and cause air bubbles. This can affect the experiment because you may mistakenly see something, but it’s air bubbles. The Cell (Image modified from http://academygenbioii.pbworks.com)

BIOL-112: Lab 1 – Microscope & Cells Cytoskeleton Contains microfilaments and microtubules Helps shape the cell Locomotion Centrioles Made up of bundles of microtubules Only in animal cells Moves chromosomes in cell Self-replicating Part 2: Label the parts of the Animal Cell shown in the picture below. (Image obtained from https://www.biologycorner.com)  In animal cells, which organelle contains its own DNA? Nucleus contains DNA  What structures are found within the nucleus? Nucleolus and chromosomes are found in the nucleus  What is the difference between the smooth and rough ER? Smooth ER helps store protein and lipids. The rough ER synthesizes and stores proteins.  According to your lab handout, what parts of cells that are visible with the light microscope? The cell membrane, nucleus, cytoplasm, and organelles are visible with the light microscope. 1. mitochondria 2. centrioles 3. lysosomes 4. cytosol 5. nucleus 6.nuclear membrane 7. chromatin 8. cytoskeleton 9. centrioles 10. smooth ER 11. cytosol 12. ribosomes 13. rough ER 14. golgi apparatus 15. cell membrane

BIOL-112: Lab 1 – Microscope & Cells Part 3: Label the parts of the Plant Cell shown in the picture below. (Image obtained from https://www.biologycorner.com)  In plant cells, which organelles contain their own DNA? Chloroplast contains the DNA.  What three structures are found in plant cells that are not found in animal cells? A cell wall, chloroplast, and central vacuole aren’t found in animal cells.  What is the difference between the cell membrane and cell wall? The cell membrane is found in all cells, and cell walls are only found in plant cells. A. nucleus B. nucleus pore C. nucleolus D. nuclear envelope E. rough ER F. smooth ER G. vacuole H. tonoplast I. chloroplast J. cell wall K. plasma membrane L. mitochondria N. golgi apparatus

BIOL-112: Lab 1 – Microscope & Cells 2.What is the advantage of staining cells with this Methylene blue? Methylene blue helps make cells easier to see. 3.What 3 structures can you see? Nucleus, cell mebrane, cytoplasm Part 6: Experiments in Plant Cells Observe the following Elodea leaf cells. 1. Identify the structures labeled here: A. chloroplast C. plasma membrane B. cell wall D. cytoplasm 2. What would happen to the cells if you added a drop of 10% NaCl at the edge of cover slip? The cells will shrivel up if 10% of NaCl is added. Observe the following onion cells. A B C D (Image from Cengage, 2013.)

BIOL-112: Lab 1 – Microscope & Cells 1. Identify the structures labeled here: A. nucleolus B. cell wall C. nucleus D. cytoplasm 2. What structures did you see in elodea cells that are not present in the onion cells? We see chloroplast. References:  https://lessonworksheets.com/concept/microscope-crossword  https://www.amscope.com/  http://academygenbioii.pbworks.com/w/page/28448029/Microscopic%20Observation%20of %20Cells  https://www.biologycorner.com/worksheets/microscope-investigation.html  https://slideplayer.com/slide/6160599/  http://ibg102report.blogspot.com/2013/04/lab-2-measurement-and-counting-of-cells_2.html  https://www.biologycorner.com/worksheets/microscope-investigation.html  https://www.biologycorner.com/worksheets/cell_label.html  http://faculty.northlandcollege.edu/biology/BioInstructors/Terry_Instruct/Publish/AP1/AP1Labs/ Lab%202/4.htm#2)_Cell_Structure  https://www.flickr.com/photos/codonaug/6936088770  https://myrcc.rcc.mass.edu/ICS/103_lab_manual/cell-structure.html