Module 1, Experiment 1:
Observing Bacteria and Blood
(No microscope needed for this lab)
A. List the following parts of the microscope, AND
Briefly describe the function of each part.
A. Eyepiece – transmits and magnifies the image from the objective lens to the eye.
B. Main tube – moves vertically for focusing
C. Nosepiece– holds the objective lenses and rotates them.
D. Objective lens - Objective lenses provide different focal lengths.
E. Stage - holds the object to be viewed
F. Diaphragm – controls the amount of light reaching the slide
G. Light source – a mirror, lamp, or bulb for illuminating slide work.
H. Course adjustment – used for the initial focusing of field
I. Fine adjustment – used for the final focusing of field
J. Arm – connects base to the viewing tube
K. Stage knobs or clips – secures and adjusts the slides position on the stage
L. Base – connects the arm and provides stability
B. Define the following microscopy terms:
a. Focus: positioning the objective lens at the proper distance from the specimen. The point at which the light from a lens comes together.
b. Resolution: The closet two objects may be before they can no longer be viewed as separate objects. This is usually measured in nanometers.
c. Contrast: The difference in lighting between adjacent areas of the specimen. Using chemical stains or adjusting the light source can adjust this.
C. You do not need to prepare a fresh yogurt slide for this lab, but you do need to observe a microscopic image of fresh yogurt. You can use a microscopic image in your textbook, or in your lab manual, or you can search online for microscopic images of yogurt. D. Are there observable differences between fresh yogurt under the microscope and the prepared yogurt slide? If so, briefly describe them. There is an observable difference. The fresh yogurt slide has less bacterial growth than the