Portage Microbiology Exam 3 Questions and Answers Already Passed

Portage Microbiology Exam 3 Questions and Answers Already Passed What is the total magnification of a sample imaged with a 60x objective and a 10x eyepiece? (short answer) 60 x 10 = 600x magnification True or False: A cell that is adherent, flat, and unstained is easily identified using bright field microscopy False. Adherent, flat cells are almost invisible due to the limits on both resolution and contrast Which of the following could be seen clearly by the unaided eye? (multiple choice) Protozoa with diameter of 150um and skin cell with diameter of 1500 um (have to be greater than 100um Label the following unmarked microscope components by matching it with the components provided 1. Eyepiece 2. Neck 3. Fine adjustment knob 4. Objective 5. Stage 6. Base This type of microscope is best suited for visualizing GFP, RFP and YFP proteins (given list of microscopes) Flourescence This type of microscope can provide detailed images of live cells without staining (given list of microscopes) Phase-Contrast This type of microscope is used to greatly increase the contrast between samples and background by reflecting light off of the specimen (given list of microscopes) Dark Field This type of microscope is capable of capturing images in multiple focal planes rendering specimen in 3D (given list of microscopes) Confocal Identify what type of electron microscope was used to capture the following image and explain your choice A: TEM, shows 2-D rendering B: SEM shows 3-D shell models Gram-Positive cells appear _____ in color due to a _____ peptidoglycan layer in the cell wall (fill in the blanks) Purple, thick Gram-Negative cells appear _____ in color due to a _____ peptidoglycan layer in the cell wall (fill in the blanks) Pink, thin True or False: The distinguishing characteristic of Gram_negative bacteria is the presence of LPS in the outer membrane True True or False: If you wish to study the motility of an organism you cannot heat fix, but you can chemically fix the specimen False. Both heat and chemical strategies will kill the cell, making motility observations impossible You want to observe the size and shape of a cell. What is the easiest staining technique that you could perform? Name at least one dye you would use during this process Simple stain. You could use any of the following: methylene blue, crystal violet, safranin, or fuschin You suspect a patient may have TB. Once a sample has been obtained, it is sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained side You would expect to see red cells (TB+) on a blue background (TB negative) True or False: If a patient is suspected of having malaria, a Giemsa stain would be an appropriate differential test to perform True. Giemsa stains are often used in the clinical setting to aid in the diagnosis of blood parasites A micrometer is defined as 10^-6 A nanometer is defined as 10^-9 True or False: A nanometer is longer than a micrometer False Resolution (short answer) Distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one Contrast (short answer) Difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. Assuming a constant (non-adjustable) light source power, identify the part of the microscope you would adjust to limit the amount of light entering the microscope (multiple choice) The iris diaphragm Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample Objective True or False: Staining is often required to image a cell that is adherent and flat (thin) True True or false: following the decolorization step of the Gram stain, Gram negative bacteria will appear colorless True Name one substance capable of chemically fixing cells to a slide Paraformaldehyde, ethanol, or methanol