It gives a general idea about bacteria- shape, size and structure. It is a part of Microbiology Syllabus in BSc (CBCS) system both Hons and Program

1. CC-1 (CBCS) Hons Program
Unit-3: Bacteria
General characteristics;
Cell structureRef : Peltzar;
Dr. Rita Som Paul
Associate Professor
Botany Department
Siliguri College
Siliguri

2. General characteristics
• I. Size – typically 0.5mm – 5.0mm
• Largest bacterium discovered –
• Thiomargarita namibiensis 750mm –visible to
the naked eye
• Smallest bacterium- Mycoplasma genitalium
• 200-300nm (0.2-0.3mm)

3. Thiomargarita namibiensis

4. II.Bacterial shape
1.Sperical
(coccus)
Rod-shaped
3.Spiral – spirillum
(rigid rod)
Spirillum volutans
4.Helix (flexible )-
spirochete
Treponima pallidum
2.Bacillus
5.Filamentous-
Actinomycetes
Eg.
Streptomeces
spp
3. Coma-shaped
Vibrioid
Vibrio colerae

5. Bacterial arrangement in coccus
3.Chains:
streptococci Eg
Streptococcus lactis
2.Diplococci –
in pairs Eg
Diplococcus
pneumoniae
6. Clusters:
staphylococci
Eg.
Staphylococcu
s aureus
5.Packets of
eight:sarcinae Eg
Sarcina lutea
1.Singly-
Micrococci
Eg. Micrococcus
luteus
4. Tetracocci- four cells
Pedicoccus cerevosae

6. Rod-shaped or bacillus
• 1. Single –
Lactobacillus,
Bacillus anthracis
• 2. In pairs –
Diplobacillus
• Corynebacterium
diphtheriae
• 3. In chains –
streptobacillus
• Bacillus cereus,
• B. tuberculosis