THE MICROSCOPE
The fundamental objectives of this report are to learn how to:
- handle and care about the microscope
- Identify various parts of the microscope such as the eye piece, arm, coarse adjustment knob, fine adjustment knob, base, nose piece, objective lenses, stage condenser, and Iris diagram.
- Define various terminologies used while using the microscope such as the total magnification, resolving power, working distance, parfocal and real and virtual images.
- And finally to observe stained slides of bacteria or the fungi.
RESULTS
Concerning how to care about the microscope, the following should be taken into consideration: while using the microscope, you are always advised to hold it using your two hands. One hand should be placed around the arm while the other one should be placed on the base of the microscope for support.
As you handle the microscope, you are also advised to be gentle. This is because setting the microscope roughly down on the table could interfere with some delicate parts of the microscope such as the lenses. As we all understand, the microscope is like a simple instrument. However, each of the lenses is made up of a number of other lenses which are very delicate hence should be handled with care. You are also advised to always have clean hands when handling the microscope.
Storing the microscope
Always keep the microscope covered when not in use because dust is a big enemy of the microscope lenses. Keep the microscope in dry and cool area.
Cleaning of the microscope
Do not let the microscope to get too dirty. You are advised to use the dust cover when the microscope is not in use. Use high quality lens paper to clean the eyepiece. Do not use facial tissues because they are made up of grounded up wood fibre hence could easily destroy the delicate parts of the eyepiece lenses?
Identification of the various parts of the microscope
Definition of terms
Total magnification is the product of both the eyepiece lenses and the objective lenses. For instance if the eyepiece lens is X10 while the objective lens is X40 then the total magnification power shall be 10× 40= X400.
Resolving power is the ability of the microscope to distinguish between two cosely adjacent points. It is the function of the light wavelength and the index of refraction of the medium through which the light must pass.
Working distance is the space between the objective and the specimen when the objective lens is in focus. The higher the magnification, the shorter the distance while the lower the magnification the longer the distance.
Parfocal is a type of lens used during the magnification and which can stay in focus when the magnification or the focal length has been changed.
Real images are the images where the light actually converges. Such images do appear or occur when objects have been placed outside the focal lengths of a converging lens or outside the focal lengths of a converging mirror. While virtual images are locations from where the light appears to have converged.
Stained slides of bacteria or fungi
When the stained slides of bacteria are placed in a microscope. What is observed depends on whether the bacteria are gram-negative or gram-positive. For instance, in gram-positive bacteria, many layers of peptidoglycan shall be observed while in the gram-negative bacteria, thin layer of peptidoglycan and an outer lopopolysaccharide layer shall be observed.
CONCLUSION
In this lab experiments, we have learned various things concerning the microscope. For instance, we have learned how to care and handle the microscope. And finally we have also identified various parts of the microscope.
MICROORGANISM IN A CULTURE
OBJECTIVES OF THE STUDY
The fundamental objectives of this report are to:
- Make aseptic transfers of pure cultures.
- Examine cultures for colonial morphologies
- Examine growth characteristics in broth medium
- And finally to define biological terms such as pure culture, culture medium and many others
Definition of terms
Pure cultures are biological cultures which contain a single species of organism. Culture medium on the other hand is defined as the medium which is specifically designed to support the growth of microorganisms or the cells. Agar is defined as the non-nutritive solidifying agent which is extracted from the sea weed. When the Agar is used in test tubes, it is referred as the Slants. And when it is used in Petri Dishes it is referred as the Plates. Petri Dishes are shallow circular glass or plastic dish with a loose fitting cover over the top and sided. Colony is a group of cells which is derived from the same initial cells. Colony morphology contains characteristics of the organisms such as the colour, shape, margin elevation among others. The cell morphology can be defined as the form and structure of organism. Sterile are organisms which are not able to give rise to fertile offspring.
RESULTS
When various bacteria are placed in a culture medium, some grow diffusely producing uniform clouding of the broth. Others look granular or the growth may appear as small puffballs floating in the broth. At time the growth may be layered at the top, middle or near the bottom and may give some indication as to the organisms oxygen requirements as there will be most oxygen at the top while the least at the bottom of the broth.
Colonial Morphology (on plates)
CONCLUSION
In conclusion, it is prudent to note that different organisms exhibit different growth characteristics patterns when placed in broth. For instance, some diffuse uniformly throughout the broth, some will sink to the bottom and end up forming sediments. Some also can float at the top of the broth. The characteristics exhibited by different organisms when placed in broth can be used to identify different unknown organisms. However, when using broth to identify unknown organisms certain precautions should be taken.
This is because the type of broth and temperatures can alter the growth patterns of different organisms. The laboratory bench top was washed with disinfectant in order to remove the infections that could be present on the bench. In order to determine if the culture is sterile place some microorganisms in the test identified and then leave it for some time. After a given period of time the organisms will be dead because sterile cultures do not support growth. Signs of bacterial growth in the broth media are presence of colloidal suspension at the bottom of the Petri dish.
Open culture tubes are always held in a horizontal position in order to maximize the surface of the culture medium inside. Single bacterial colony is used to start pure cultures in order to avoid contamination with other colonies. It is important to work with microorganisms in pure cultures rather than with a mixture of organisms in order to avoid contamination.
CULTURING MICROORGANISMS FROM THE ENVIRONMENT AND THE BODY
OBJECTIVES
The fundamental objectives of this laboratory exercise are to: culture microorganisms from the selected areas of the environment. To demonstrate the abundances of microorganisms in different environments. To culture normal flora from at least one body. And finally, to define different biological terminologies such as nosocomial.
Definition of terms
Normal Floras are the microorganisms in the body. It can also be defined as the organisms that reside on the surface and in deep layers of skin in the saliva and the oral cavity. Nosocomial is something which has its origin from the hospital. For instance, diseases or infections originating from the hospital is known as nosocomial. Immunocompromised is an immune system that is incapable of developing a normal immune system. Epidemiologist is a medical scientist who studies the transmission and control of a given disease among a given population.
RESULTS
Different environment were used to find out the environment which contain large number of bacteria colony. Some of the environments which were used for this experiment include: floor, bathroom air, hands, cell phone, toilet and bathroom. The results are as shown in the table below. The floor recorded the highest number of bacteria while the bathroom recorded the lowest number of bacteria.
Conclusion
In conclusion, it is worth noting that microorganisms are ubiquitous; they are found in different environmental conditions such as the air, water, soil, dust hands, floor cell phone and many others.
Inoculated plates are incubated in the vertical position in order to avoid formation of moisture. It is made up of tryptone, Soytone and sodium chloride. Blood agar is made up of blood cells from sheep, sugar galactose and most bacteria. The procedures done in this laboratory experiments is not appropriate for growing all microorganisms because it was specific for pure culture. If there is no growth on one of the inoculated plates then the culture is sterile. This is because sterile culture does not support growth.
MICROBIAL STAINING TECHNIQUES
OBJECTIVES
The fundamental objectives of this paper is to: perform a gram stain reaction, know the sequence of steps to perform a gram stain including the reagents used and the timing of applications, to understand the purpose of each step in the gram stain, learn the Gram reactions of the bacteria stained in this exercise and to define various biological terms such as the Aniline Dye.
Definition of Terms
Aniline dyes are synthetic organic dyes which are made from coal-tar products and are used routinely to stain bacterial cells so that the contours of the microorganism can be clearly visualised under the light microscope. The Aniline dye can be acidic, basic or neutral. The acidic dyes contain anions while the basic dyes contain cations.
Cations are the positively charged molecules while Anions are the negatively charged molecules. Simple stains involve colouring bacterial cells with a single dye reagent while differential stains provide a method to distinguish between types of bacteria.
RESULTS
Flood the slide on the staining rack with Hucker’s crystal violet and allow it to react for 1minute. Rinse the stain off the slide by gently applying a stream of water. Flood the slides with Gram’s iodine and allow it to react for one minute. Rinse the slides as in step two and record the results. The results are as shown in the table below.
It is prudent to note that cells are blue/purple (Gram positive) or pink/red (Gram negative). However, the exact mechanism through which the stain acts is not comprehensively understood by scientist.
Conclusion
This makes it difficult to differentiate between the bacteria. You will not be able to distinguish between the bacteria present since all of them will have the same colour.th decolourization step is the most crucial step for accurate results because it enables you to differentiate between the gram positive and gram negative bacteria. Safranin gives pink or the red colour to the Gram’s negative bacteria. It also helps in differentiating them from gram positive bacteria that may have a violet or purple colour because of primary stain of crystal viol
STREAKING A MIXED BROTH CULTURE FOR COLONY ISOLATION
OBJECTIVES OF THE LAB EXERCISE
The fundamental objective of this lab exercise is to: isolate pure culture from specimen containing mixed flora. To culture and study the normal flora of the human mouth and finally to define certain biological terms.
Definition of terms
Mixed cultures are biological cultures that contain more than single species of organism. Pure cultures are biological cultures which contain a single species of organism. Normal Floras are the microorganisms in the body. It can also be defined as the organisms that reside on the surface and in deep layers of skin in the saliva and the oral cavity. Pathogens are disease causing organism. Streak dilution is a technique of diluting bacteria down sufficiently so as to ensure that they grow as single colonies. The method varies from individual to individual.
RESULTS
The reaction was done using the gram stain. The gram reaction, cell morphology and identifications were observed as follows. In grape-like cluster, the Gram reaction was positive. This was the same in cocci cells and the grape-shape cluster.
Conclusion
In conclusion Streak dilution is a technique of diluting bacteria down sufficiently so as to ensure that they grow as single colonies. The method varies from individual to individual.
