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TNPSC Free Notes Biology – Bacteria

இந்தக் கட்டுரையில், TNPSC குரூப் 1, குரூப் 2, குரூப் 2A, குரூப் 4 மாநிலப் போட்டித் தேர்வுகளான TNUSRB, TRB, TET, TNEB போன்றவற்றுக்கான  முறைகள் இலவசக் குறிப்புகளைப் பெறுவீர்கள்.தேர்வுக்கு தயாராவோர் இங்குள்ள பாடக்குறிப்புகளை படித்து பயன்பெற வாழ்த்துகிறோம்.


• Bacteria are prokaryotic, unicellular, ubiquitous, microscopic organisms.
• The study of Bacteria is called Bacteriology.
• Bacteria were first discovered by a Dutch scientist, Anton van Leeuwenhoek in
• Robert Heinrich Hermann Koch was a German physician and microbiologist. He
is considered as the founder of modern bacteriology.
• He identified the causal organism for Anthrax, Cholera and Tuberculosis
Milestones in Bacteriology
• 1829 C.G. Ehrenberg coined the term Bacterium
• 1884 Christian Gram introduced Gram staining method
• 1923 David H. Bergy published First edition of Bergey’s Manual
• 1928 Fredrick Griffith discovered Bacterial transformation
• 1952 Joshua Lederberg discovered of Plasmid

General characteristic features of Bacteria
• They are Prokaryotic organisms and lack nuclear membrane and membrane
bound organelles.
• The Genetic material is called nucleoid or genophore or incipient nucleus
• The cell wall is made up of Polysaccharides and proteins
• They reproduce vegetative by Binary fission and endospore formation
Ultra structure of a bacterial cell
The bacterial cell reveals three layers
1. Capsule/Glycocalyx
2. Cell wall and
3. Cytoplasm
• A thick layer of glycocalyx is bound tightly to the cell wall is called capsule.
• It protects cell from desiccation and antibiotics.
Cell wall
• The bacterial cell wall is granular and is rigid.
• It provides protection and gives shape to the cell.
• The chemical composition of cell wall is rather complex and is made up of
peptidoglycan or mucopeptide
Cytoplasm is thick and semi transparent. It contains ribosomes and other cell
Types of Bacteria according to Flagella
1. Monotrichous – Vibrio Cholera
2. Amphitrichous – Rhodospirillum
3. Lophotrichous – Pseudomonas
4. Atrichous – Coryne bacterium.
Human Bacterial Diseases

Diseases Causative agent Site of

Mode of transmission Symptoms

1 Shigellosis

Shigella sp. Intestine Food and water
contaminated by faeces
/ faecal oral route

Abdominal pain, dehydration,
blood and mucus in the stools

2 Bubonic plague
(Black death)

Yersinia pestis Lymph nodes Rat flea vector-
Xenopsylla cheopis

Fever, headache, and swollen
lymph nodes

3 Diphtheria Corynebacterium

Larynx, skin,
nasal and
genital passage

Droplet infection Fever, sore throat, hoarseness
and difficulty in breathing

4 Cholera Vibrio cholerae Intestine Contaminated food and
water/ faecal oral route

Severe diarrhoea and

5 Tetanus(Lock

Clostridium tetani Spasm of

Through wound

Rigidity of jaw muscle, increased
heart beat rate and spasm of the
muscles of the
jaw and face

6 Typhoid (Enteric

Salmonella typhi Intestine Through contaminated food

and water

Headache, abdominal
discomfort, fever and

7 Pneumonia Streptococcus

Lungs Droplet infection Fever, cough, painful
breathing and brown sputum

8 Tuberculosis Mycobacterium

Lungs Droplet infection Thick muco purulant nasal


Fungal diseases
 Fungi were recognized as a causative agent of human diseases much earlier
than bacteria.
 Dermatomycosis is a cutaneous infection caused by fungi belonging to
the genera Trichophyton, Microsporum and
 Ringworm is one of the most common fungal disease in humans
 Ringworms of the feet is known as Athlete’s foot caused by Tinea pedis
 Ringworms are generally acquired from soil or by using clothes, towels and
comb used by infected persons
Helminthic diseases
 Helminthes are mostly endoparasitic in the gut and blood of human beings
and cause diseases called helminthiasis.

 The two most prevalent helminthic diseases are Ascariasis and Filariasis.
 Ascaris is a monogenic parasite and exhibits sexual dimorphism.
 Ascariasis is a disease caused by the intestinal endoparasite Ascaris
lumbricoides commonly called the round worms.
 It is transmitted through ingestion of embryonated eggs through
contaminated food and water
 It may also cause enteritis, hepatitis and bronchitis.
 Filariasis is caused by Wuchereria bancrofti, commonly called filarial
 It is found in the lymph vessels and lymph nodes of man.
 The accumulation of the worms block the lymphatic system resulting in
inflammation of the lymph nodes.
 In some cases, the obstruction of lymph vessels causes elephantiasis or
filarias is of the limbs, scrotum and mammary glands
Immunization schedule followed in India
New born BCG 1st dose
15 days Oral Polio 1st dose
6th week DPT and Polio 1st dose
10th week DPT and Polio 1st dose
14th week DPT and Polio 1st dose
9 – 12 months Measles 1st dose
18 – 24 months DPT and Polio 1st dose
15 months – 2 years MMR 1st dose
2 – 3 years TAB 2 doses at 1 month gap
4 – 6 years DT and Polio 2nd booster
10th year TT and TAB 1st dose
16th year TT and TAB 2nd booster

Protozoan diseases

About 15 genera of protozoans live as parasites within the human body and cause
• Amoesbiasis also called amoebic dysentery or amoebic colitis is caused by
Entamoeba histolytica, which lives in the human large intestine and feeds on
mucus and bacteria.
• Infective stage of this parasite is the trophozoite, which penetrates the walls of the
host intestine (colon) and secretes histolytic enzymes causing ulceration, bleeding,
abdominal pain and stools with excess mucus.
• House flies (Musca domestica) acts as a carrier for transmitting the parasite from
contaminated faeces and water.
African sleeping disease
• African sleeping sickness is caused by Trypanosoma species.
• Trypanosoma is generally transmitted by the blood sucking Tsetse flies.
• Three species of Trypanosoma cause sleeping sickness in man.
1. T. gambiense – is transmitted by Glossina palpalis (Tsetse fly) and causes
Gambian or Central African sleeping sickness
2. T. rhodesiense- is transmitted by Glossina morsitans causing Rhodesian or East
African sleeping sickness.
3. T. cruzi – is transmitted by a bug called Triatoma megista and causes Chagas
disease or American trypanosomiasis.
Kala – azar
• Kala – azar or visceral leishmaniasis is caused by Leishmania donovani, which is
transmitted by the vector Phlebotomus (sand fly).
• Infection may occur in the endothelial cells, bone marrow, liver, lymph glands
and blood vessels of the spleen.
Malaria is caused by different types of Plasmodium species such as
1. P. vivax
2. P. ovale

3. P. malariae and
4. P. falciparum
• Plasmodium lives in the RBC of human in its mature condition is called as
• It is transmitted from one person to another by the bite of the infected femaleAnopheles mosquito


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