Page 19 - MNU microbiology theoritical 2025
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General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025
3) Shape and Arrangement
A- Coccus; Spherical cells
– Diplococci: Pairs of cocci remain associated after cell division (Streptococcus
pneumoniae)
– Chains: Chains of cocci remain associated after cell
division (Streptococcus pyogenes)
– Staphylococci: Clusters of cocci (grape like
structure (Staphylococcus spp.)
– Tetrads = square (Micrococcus luteus)
– Sarcina = Cubical, eight cell cluster (Sarcina spp.)
B- Bacilli
- Single rods scattered: No special arrangement. ex: E. coli
- Diplobacilli: pairs of bacilli
- Streptobacilli: Chains of bacilli
- Palisades shape ex: Corynebacteria diphteria
General Microbiology & Immunology (PM 401) theoretical handbook Page 8
