SS1 Second Term Biology Lesson Note – Micro Organism Around Us

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WEEK 10

BIOLOGY

TOPIC: MICRO ORGANISM AROUND US

CONTENT:

• Microorganism in air and water.
• Group of microorganisms: bacteria, viruses, some algae, protozoa, fungi.
• Concept of culturing
• Identification of micro-organism in (i) Air (ii) pond water (iii) river (iv)concept of culturing
• Micro-organisms in our bodies and food.
• Carriers of microorganisms – examples, location of the micro-organism in carriers and types of microorganism.

SUB-TOPIC 1: MICRO ORGANISMS IN AIR AND WATER.

Introduction: Micro-organisms are very tiny living organisms are also known as microbes.

T-Lymphocyte Infected With HIV

Human immunodeficiency virus (HIV) is the cause of acquired immunodeficiency syndrome (AIDS). By infecting CD4 T-lymphocytes, a type of white blood cell, HIV weakens the immune system and leaves the infected individual open to deadly infections. The viruses gain access to a T-lymphocyte by attaching to CD4 proteins on the outer surface of the cell membrane.

MICROBES

Anthony Van Leeuwenhoek (1632 – 1733) was the first scientist to discover microbes with his newly invented microscope.

Micro-organisms are dreaded as disease causing agents (germs). However, many microbes are of great benefits to man e.g. saprophytic microbes that bring about decay of organic matter. Those microbes that affect man negatively are mainly the parasitic ones which are called pathogem.

Microorganism are found everywhere- in the air, water, soil, in our own food, on our food on surfaces of object, and on inside living organisms, on our bodies, inside of our bodies and on our clothes in shut, anywhere everywhere.

Groups of micro organisms:

Microbes are very many and are grouped as follows:

1. Bacteria
2. Viruses
3. Some algae
4. Protozoa
5. Some fungi

Most microbes are unicellular but some fungi and algae are multi-cellular. Several microbes survive adverse conditions of temperature or humidity by forming spaces the within the cell. On the return of favourable condition of the spores are released carried in the air and on landing on suitable substrate grow and produce more spores.

Hepatitis B Virus

The hepatitis B virus (HBV) causes inflammation of the liver. The virus is recognizable under magnification by the round, infectious “Dane particles” accompanied by tube-shaped, empty viral envelopes. Symptoms of hepatitis B infection include jaundice and a flulike illness, while chronic infection can lead to serious problems such as cirrhosis and cancer of the liver.

BACTERIA

Bacteria can be seeing with the use of light microscope. It has a simple structure. It is unicellular. It is a prokaryotic cell i.e it does not have a true nucleus. Heredity materials are contained in a strand of DNA (Deoxyribose nucleic acid) inside the cell.

Bacteria can be described based on the following:

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