Observing Bacteria and Blood- Lab #1 Essay

Concept 6.1 Biologists use microscopes and the tools of biochemistry to study cells 1. The study of cells has been limited by their small size, and so they were not seen and described until 1665, when Robert Hooke first looked at dead cells from an oak tree. His contemporary, Anton van Leeuwenhoek, crafted lenses and with the improvements in optical aids, a new world was opened. Magnification and resolving power limit what can be seen. Explain the difference. Magnification is the ratio of an object’s image size to its real size. Resolution is a measure of the clarity of the image; it is the minimum distance two points can be separated and still be distinguished

Preparing specimen for electron microscope hard, light microscope still very useful as a window on living cells.

The next step of the project included preparing a Gram stain to discover the cell shape, arrangement, and if the bacteria is gram positive or

1) Apply the stain to your first unknown slide and examine it under the microscope.

There are several sections to this lab. Find each section and complete the “Preparing for Class” sections.

The illuminating parts of a microscope enable us to see the detail of the subject placed under the microscope. The three main parts that enable us to do this are: the condenser which illuminates the object that is placed under the microscope, the objectives which forms the magnified image, and the eyepiece which enables us to see the magnified

FIGURE 1.7- A magnified view of a single lenslet shows a portion of an aberrated wavefront (red curve) passing through. If the wavefront had been flat (aberration-free), it would have focused to a point on the video sensor (CCD) on the lenslet's optic axis (yellow dot). Refractive errors distort the wavefront out of a plane, so a wavefront portion (red curve) enters the lenslet curved and tilted. The light will therefore be focused to another part (red dot). The dot will be shifted by an amount that is in direct proportion to the wavefront tilt.

A light microscope was set up with the light on a low setting; one large Daphnia was selected and placed in the centre of a cavity slide by using a pipette.

The drops of crystal violets, approximately 15 drops, were flooded until the smear were all covered and then allowing resting for one to two minutes. After two minutes, the slide was titled over the sink and washed off, with the distilled water bottle, by aiming the stream of water above the smear. The specimen appeared blue-violet when observed with the naked eye. The drops of Gram’s iodine were applied on the slide until covered and then allowed to react for one minute or more. After the time elapsed, the slide was rinsed again with distilled water following immediate drops of Gram stain decolorizer added one drop at a time.

Then, put the depression slide underneath the microscope start on the medium objective and work your way up to the high objective.

Another limitation is out of focus light from outside the focal plane reducing image clarity or requiring constant adjusting.  On the other hand, under the right conditions, light microscopy allows for viewing of samples that are still alive.  There are aids such as fluorescent proteins, that can be used to track proteins in real-time in cells though the viewing of where the proteins are may not be very high in resolution, you may see roughly where the protein is in the cell, but will not be able to see the shape of the protein itself. Lastly confocal light microscopy gives moderately higher resolution, and significant enhancements in optical sectioning by limiting out-of-focus light.

Preparation is a key to success in this lab. For this reason, you are required to thoroughly read through the experiment information presented in the lab manual, and complete a pre-lab for each experiment you do. The prelab must be completed prior to the day of the experiment. Each Friday I will ask to see your completed prelab before I allow you to enter the lab. If you have not finished the pre-lab, I will not allow you to enter the lab and you will receive a zero.

This lab and its procedures are all about finding out the unknown identification of a given bacteria. The lab consists of specific techniques, tests, chemicals, and vocabulary that are necessary for the finding of the bacterial identity. A bacterium is randomly assigned and it is a group effort to find the bacteria name through many of its specialties and characteristics. An example of classifying it would be to determine whether the bacteria is catalase negative or positive, or if the species is gram negative or positive. This lab is of huge significance because of its medical microbiology connections. Scientists Gurtler and Stanisich explained the connections more eloquently. They stated, in their medical article, that, “Medical microbiology

2. Introduction: Each student was given unknown bacteria and was instructed to perform a variety of experimental tests that would help to identify their bacteria. During the process of identification, the unknown bacteria was added to many different testing medias using aseptic technique. They are as follows: lactose fermentation on eosin methylene blue (EMB), TSI (Triple Sugar Iron agar), Phenol red sucrose, the SIM test, H2S by SIM, IMViC (indole, motility, voges-proskauer, and citrate), Urease (urea broth), PDase (Phenylalanine Deaminase), Lysine Decarboxylase, and Ornithine Decarboxylase. Colonial morphology on EMB was used to

Most microscopes, including those in schools and laboratories today, are optical microscopes. They use glass lenses to enlarge, or magnify, an image. An optical microscope cannot produce an image of an object smaller than the length of the light wave in use. To see anything smaller than 2,000 angstroms (about 1/250,000 of an inch) a wave of shorter length would