Lesson Notes By Weeks and Term - Senior Secondary 1

TERM – 3^RD TERM

WEEK FOUR

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: CONCEPTS OF CULTURING

OBJECTIVES: At the end of the lesson, pupils should be able to

1. Define culturing
2. Identify microorganisms in air
3. Identify microorganisms in water
4. Identify carriers of microorganisms.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS:  Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

CONCEPTS OF CULTURING

Culturing microorganisms is a fundamental technique in microbiology that involves encouraging the growth of microorganisms under controlled laboratory conditions. This process allows researchers to isolate, identify, and study specific microbial species.

Identifying microorganisms in 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:

(a) Bacteria: Examples – Pneumococci, Staphylococci, Streptococci, Bacillus anthracis, which causes anthrax in herbivores.

(b) Virus: examples – Influenza, Polio virus, common cold virus, measles virus.

(c) Fungi: Examples – Sacromyces (yeast), Rhizopus nigricans (bread mould), Penicillium (blue-green mould) Aspergillus etc.

Bacterial Cultures

Colonies of the bacteria known as Escherichia coli (larger, pink) and Proteus vulgaris (smaller, brown) grow side by side in this petri dish culture. Under normal circumstances both of these bacteria harmlessly inhabit the human intestines and aid in digestion, but can become pathogenic and cause infections, such as urinary tract infections. Scientists and doctors grow cultures of bacteria and study their characteristics in order to learn about bacterial diseases and disease prevention.

Identifying microorganisms in Water

Micro organisms found in water are commonly known as plankton. Aquatic environment, unlike atmosphere are rich in organic and inorganic nutrients. They can be found in all types of water habitat viz: wells, ponds, lakes, streams, rivers and seas.

All microbes found in water can be grouped into three as follows:

1. Natural water micro-organisms: these are microbes that are naturally found in aquatic habitats.
2. Soil micro organism ( washed into the surrounding water bodies during heavy rains)
3. Sewage micro-organisms

Microorganisms in water their examples

I. Bacteria: Examples – aquatic species of coccus, Baccillus, Pseudomonas, Azobacter, Thiobacillus, Sarcinina, spirillum, Micrococcus, Vibro and Spirochaeta. These bacteria are either heterotrophic, autotrophic and chemotrophic.

II. Blue green algae: Examples; oscillatoria, nostoc, anabaena,

III. Protists: These are autotrophic diatoms e.g. chlamydomonas, cholera and some species of euglena as well as heterotrophic amoeba and paramecium.

IV. Algae: These are located close to the shore of where they form thick green floating mesh e.g. spirogyra, volvox etc. Algae arte major part of primary producers in the aquatic habitat since they contain chlorophyll and can photosynthesis.

Microorganisms in our bodies and food

Microorganisms in our bodies include bacteria, viruses, fungi, and archaea. In the digestive system, bacteria aid in digestion. In food, common microorganisms are bacteria, yeast, and molds, playing roles in fermentation and spoilage.

In our bodies, microorganisms enter through various routes. The digestive system encounters them through food and drink. The respiratory system can inhale airborne microorganisms, while the skin is a barrier against external microbes.

In food, microorganisms can be present naturally or introduced during processing. Raw foods like fruits and vegetables may carry surface bacteria. During handling and processing, contamination can occur, and improper storage conditions may foster microbial growth. Fermentation processes intentionally introduce microorganisms, as seen in yogurt or sauerkraut production.

Carriers of microorganisms

Microorganisms can be carried and transmitted through various means. Common carriers include:

1. Humans: People can carry microorganisms on their skin, in their respiratory secretions, and in their digestive system. This includes bacteria, viruses, fungi, and other pathogens.
2. Animals: Pets and livestock can carry microorganisms that may be harmful to humans, and vice versa. Zoonotic diseases are infections that can be transmitted between animals and humans.
3. Water: Water sources, including rivers, lakes, and oceans, can carry a variety of microorganisms. Some of these microorganisms may be harmful and cause waterborne diseases.
4. Food: Contaminated food, either through improper handling or processing, can be a source of microorganisms. Bacteria like Salmonella and Escherichia coli (E. coli) are examples of pathogens that can be transmitted through contaminated food.
5. Insects and other vectors: insects like flies and mosquitoes can carry microorganisms from one place to another, transmitting diseases in the process.
6. Air: Microorganisms can be present in the air, especially in respiratory droplets expelled when people cough or sneeze. This is a common mode of transmission for respiratory viruses.

EVALUATION: 1.what is culturing

2. Identify five microorganisms in water
3. How do Microorganisms get into our bodies
4. Enumerate four carriers of microorganisms.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively