Observing Bacteria and Blood
Cynthia Alonzo, M.S. Version 42-0249-00-01
Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.
Exercise 1: Viewing Prepared Slides
Questions A. Identify the following parts of the microscope and describe the function of each.
A - EYEPIECES
B – MAIN TUBE
C – NOSE PIECE
D – OBJECTIVE LENS
E - STAGE
F - DIAPHRAGRAM
G – MIRROR
H – COARSE ADJUSTMENT KNOB
I – FINE ADJUCTMENT KNOB
L - BASE
K –STAGE CLIPS
Define the following microscopy terms:
Focus: refers to the movement of a specimen closer or away from the objective lens to render a sharp or well-defined image.
Resolution: This is the ability of the lenses to bring a specimen into fine detail which can be distinguished
Contrast: This refers to the difference in lighting between adjacent areas of the specimen.
B. What is the purpose of immersion oil? Why does it work?
Immersion oil is a special oil used with the 100x objective lens, which acts as a bridge between the glass slide and the glass of the objective lens to increase the resolution of an image. A drop of the oil is placed upon the glass slide and the objective lens is lowered until it touches the drop and then image is brought to focus. This concentrates the light path and increases the resolution of the image
Exercise 2: Observing Bacteria Cultures in Yogurt Questions
A. Describe your observations of the fresh yogurt slide.
The fresh Yogurt slide had a cluster of round shape bacteria’s. There was some activity of movement of the round shape bacterium from one end to the other.
B. Were there observable differences between your fresh yogurt slide and the prepared yogurt slide? If so, explain.
The prepared yogurt slide did not have any movement and was not clustered as the fresh yogurt slide. There were also different shaped bacterial some were round shape and others were rod shaped.
C. Describe the four main bacterial shapes.
Cocci – are spherical shaped bacterium, but can be oval, flattened, elongated on one side Bacillus – are rod- liked shape bacterium
Spirillum – are spiral – shaped bacteria (like the cock crew) Vibrio – are curve rod shaped bacterium
D. What are the common arrangements of bacteria?
Diplo – This is when the bacteria cells remain paired.
Strepto – This is when the bacteria divide and remains attached in s chainlike pattern Staphylo – This is when the bacteria divide into multiple planes and form a grape like cluster
E. Were you able to identify specific bacterial morphologies on either yogurt slide? If so, which types?
Yes, I did. With the already prepared stained yogurt slide, I observe Bacillius and Cocci bacterial morphologies. On the fresh yogurt slide I observed a cluster of spherical shaped bacterium, which is Staphylococci bacterial morphology.
Exercise 3: Preparing and Observing a Blood Slide Questions
A. Describe the cells you were able to see in the blood smear.
The cells that I was able to observed from the blood smear, was flattish and round in shape with an indented center like the doughnuts without hole and appears to red. There was also some fluid like water, which I presume to be the plasma.
B. Are the cells you observed in your blood smear different than the bacterial cells you have observed? Why or why not?
Yes, the cells observed from the...
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