Name and Section: Patricia Ranaudo, Section 705
Title and Number: Observing Bacteria and Blood, Assignment #1

Purpose: The purpose of this experiment is to learn how to use a compound microscope and an oil immersion lens by observing (and preparing) prepared slides of bacteria and blood, to identify and observe various bacterial shapes and arrangements in a yogurt culture and to identify and observe red and white blood cells in a blood smear.
Procedure: After reviewing the section of the manual as instructed I cleaned the ocular lenses and prepared the slides. I made required adjustments to the microscope and ocular distances for view during experiment. I practiced using six prepared slides that were in the kit to ensure I was viewing the slides accordingly. I placed a drop of oil onto the slide and rotated it until bringing it to fine focus on the microscope. I then observed the same slides in part 1 but I added the oil immersion to view the differences. The difference was in the magnification and the ability to see more of the substances in finer view. I then made my own sample of yogurt, I left it undisturbed for 24 hours and observed it under the microscope. I viewed the specimen under the microscope. I pricked my finger with the sterilized pin and placed my blood on a slide with a slip cover. I observed the specimen under the microscope. I placed the prepared slide with my blood on the microscope stage, and brought it into focus on low power. I saw a lot of tiny particles that appeared to be blood cells through the microscope.

Data Table:
Exercise 1: Viewing Prepared Slides Prepared Slide | 10X | 40X | 100X | Bacterial Cocci | Groups of spheres | No visible nucleus | Diploid spherical shape with nucleus | Bacterial Bacillus | Small purple dots | Rod/single shapes | Rod/single shapes in groups. No visible nucleus | Bacteria Spirillum | Clusters | Squiggles starting to appear | Spirochete shape with nucleus | Amoeba proteus | Blob with irregular border | Visible nucleus with organelles | Nucleus, organelles and cell structure | Penicillum w/conidia | Small blue dots | Blue clusters with yellow “rods” | Yellow “rod” have nucleus? | Anabaena, w.m. | Large mass | Spheres with chains | Long chained spheres | Excercise 2: Observing Bacteria Cultures In Yogurt Slide | 10x | 40x | 100x | Fresh Yogurt | Difficult to see | Clumps | Hard to distinguish shapes | Prepared Yogurt | Small purple dots | Shapes beginning to form | Some rods visible |
Exercise 3: Preparing and Observing a Blood Slide Slide | 10x | 40x | 100x | Blood Smear | Round red cells | Clumps of red cells | Round cells with white blood cells visible. Could see nucleus of these. |
Results/Analysis: Using the microscope and immersion oil lens, I was able to view and distinguish various shapes and structures of different microorganisms and document my observations. Through preparation and examination of yogurt and blood, I was also able to view various bacterial shapes.
Exercise 1:
A. Identification and function of different parts of the microscope: * Stage – is where the specimen is placed.
* Clips – hold the specimen in place.
* Lamp – produces the light.
* Condenser – a lens that focuses and aligns the light from the lamp to the specimen. * Diaphragm – is located in the light path to modify the measure of light reaching the condenser. * Objective lens – intakes the light from the specimen. * Eyepiece – to transmit and enlarge the image from the objective lens to your eye. * Nosepiece – a revolving support system that holds objective lenses. * Tube – holds the eyepiece at the appropriate distance from the objective lens and blocks out unwanted light. * Coarse-focus knob – brings the slide sample into the focal plane of the objective lens. * Fine-focus knob – makes the appropriate adjustments to focus the image. * Arm – a curved portion that holds all of the optical parts at a fixed distance and aligns them. * Base – is the bottommost part of the microscope that supports the weight of all the microscopic parts. * Tube – is connected to the arm and supports the eyepiece and objectives.

B. Definition of the following terms:
* Focus: to position the objective lens at the proper distance from the specimen. * Resolution: The closest two objects can be before they are no longer detected as separate objects. * Contrast: How well the specimen stands out from the background.

C. The purpose of immersion oil and how it works:

Immersion oil is used to enhance the resolution power of the microscope. When oil is placed between the slide and objective it increases resolution by preventing the loss of light due to the bending of light rays as they pass through the air.

Exercise #2:
A. Description of fresh yogurt slide:

After leaving out fresh yogurt for duration of 24 hours, the results of the microscopic observations were as follows:

Under 40x magnification – a view of loads of bacteria moving about with undefined shapes.

Under 100x magnification – an indistinct view of loads of varied bacteria moving about, such as diplococci, streptococci, staphylococci, diplobacillus, and streptobacillus.

B. Description of difference(s) between fresh yogurt and prepared yoghurt slide:

The bacteria in the fresh yogurt moved around and about while the bacteria in the prepared yogurt remained motionless. There was an excessive amount of bacteria in the fresh yogurt, far more than in the prepared yoghurt. The fresh yogurt contained many different forms of bacteria, such as diplococci, streptococci, staphylococci, diplobacillus, and streptobacillus, while the prepared yoghurt contained very few forms, such as bacilli and diplobacilli.

C. Description of the four main bacterial shapes:

Coccus bacteria – spherical shaped bacteria.
Spirillum bacteria – curved or spiral shaped bacteria.
Bacillus bacteria – rod shaped bacteria.
Vibrios bacteria – comma shaped bacteria.

D. The common arrangements bacteria are found in bacteria:

* Diplo- pairs
* Strepto-strands
* Staphylo-clusters

Exercise #3:

A. Describe the cells you were able to see in the blood smear.

I saw mostly red blood cells and white blood cells which were the most abundant within the sample. The red blood cells appeared a reddish purplish color with an oblong and symmetrical appearance and the white blood cells had a light blue appearance.

B. Are they different than the bacterial cells you have observed? Why or why not?
Yes. The individual structures showed much variation from the bacteria and the group formations were different. The blood slide cells were very round and definable. while he bacterial slide cells were all different shapes and not very definite in their shape.

Conclusion/Discussion:

By examining slides of different samples, I was effectively able to obtain a well-rounded understanding of the function and use of the microscope along with the knowledge of bacterial differences. By starting off the exercise focusing the microscope on the letter ‘e’ slide, and then on six other prepared slides, I gained experience in utilizing the microscope and oil immersion lens. After identifying the structure and detail of each bacteria under the 10x and 40x objective lenses, I moved on to learn and visualize the three most common bacterial shapes – bacteria spirillum, bacteria coccus, and bacteria bacillus. After a thorough examination of each of the three bacteria and after learning how to use the 100x immersion oil objective lens, I then progressed onward to observe the subtle differences between the prepared yogurt slide and the fresh yogurt slide. I also observed and learned the difference between red blood and white blood cells.
By using the various lenses on the microscope, along with the oil immersion lens, we can see how the microscope helps to distinguish the various shapes and structures of bacteria.