SS1 Biology Lesson Note on Concept of Culturing

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CONCEPT OF CULTURING

Culturing is a technique of growing micro-organisms in the laboratory for the studying the microbes.

The process has to do with:

1. Preparing a sterile medium
2. Inoculating
3. Incubating
4. Examining micro-organism in the medium.

While bacteria, fungi and algae can be grown in test tubes and Petri dishes in culture media, viruses cannot be grown. They can only grow and multiple inside living cells of an organism.

Through Tissue culture, living tissues and cells of multi-cellular organism are cultured in appropriate media and studied. To carry out studies involving viruses, are cultured in the laboratory by injecting the virus into the fertilized Bird egg e.g. egg of duck.

On the culture medium, micro-organisms occur as colonies. Colonies of micro-organism do clump together in large number of organism of the same kind. Colour, appearance other characteristics of the colonies enable the investigator to identify and differentiate microbes in a culture medium.

EVALUATION

1a. What are Micro-organism?

1. List the important groups, giving examples of each group.

2a. Expalin the concept of culturing.

1. What steps will you take in preparing a culture solution and state precautions in preparing it.
2. Identify sources of samples for culturing.

ASSIGNMENT

1. Read up Identification of Micro-organisms in the Air, Pond water, Rivers and Streams and Micro-organism in our bodies and food.
2. Read more on concept of culture. Modern Biology Pg 166-170 and

(a) outline different types of culture.

(b) state the importance of tissue culture.

SUB-TOPIC 2: IDENTIFICATION OF MICRO-ORGANISMS IN AIR, POND WATER, RIVER, STREAM

1. Micro-organisms in our bodies and food.
2. Carries of Micro-organisms, examples, location of the Micro-organisms in carries.
3. Types of micro-organisms.

MICRO-ORGANISMS IN THE AIR

Micro-organisms commonly found in the air are: Bacteria, Virus and Fungi. These microbes do not grow in the air but are present as spores in dust and water droplets in the air. These  spores are light and easily dispersed by air movement. When these spores land on suitable substrate, they germinate, multiply and produce more spores. Micro-organisms found in the air and examples:

1. Bacteria: Examples – Pneumococci, Staphylococci, Streptococci, Bacillus anthracis, which causes anthrax in herbivores.
2. Virus: examples – Influenza, Polio virus, common cold virus, measles virus.
3. Fungi: Examples – Sacromyces (yeast), Rhizopus nigricans (bread mould), Penicillium (blue-green mould) Aspergillus etc.

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