Cell Size, Shape And Arrangement
- 1. CELL SIZE, SHAPE AND ARRANGEMENT PRESENTED BY AVIJIT BANERJEE 1st SEMISTER (2017) B.Sc Hons. DEPERTMENT OF MICROBIOLOGY MICHAEL MADHUSUDAN MEMORIAL COLLEGE
- 2. Introduction - Bacterial cells are prokaryotic cells having very small size and different types of shapes. More over these cells are arranged on different planes to form various arrangement . But their cellular structure is simpler than other multicelluar eukaryots. Due to presence of a rigid cell wall outside the cell, bacterial cells has a definite shape as well as size and structures. CELL SIZE, SHAPE AND ARRANGEMENT
- 3. BACTERIAL CELL SIZE Measurement of bacterial cell Scale 1m=1000mm 1mm=1000µm 1µm= 1000nm Now, bacterial cells are measured by micrometer and the cell organelle and their thickness are measured by nanometer .
- 4. Largest bacterial cell- The largest bacterial cell is Bacillus megaterium . a. It may be visible through naked eye. b. Its length is about 600µm. c. Its diameter is about 80µm. Bacterial cells are observed in various sizes. Smallest bacterial cell- In early days it was found that Streptococcus pneumoniae was the smallest bacterial cell. Fig-Bacillus megaterium Fig-Streptococcus pneumoniae
- 5. Interisting features of Mycoplasma sp. a. It lacks cell wall. b. Outer membrane is cytoplasmic membrane. c. As the cell wall is absent, they are unaffected by many common antibiotics such as penicillin or other β-lactam antibiotics that target cell wall synthesis. d. They can be parasitic or saprotrophic. But now a days, it has been found that Mycoplasma sp is the smallest bacterial cell. Parasitic form of Mycoplasma - Mycoplasma pneumoniae. Fig-Mycoplasma sp
- 6. Some other bacteria with different size 1. Escherichia coli- Length- 3µm Diameter- 1µm. Interesting features a. These are the most well known and diverse species of microbs in the world. b. They are mostly harmless and found in Fig-Escherichia coli gastrointestinal tracts of humans and other vertebrates. c. They can synthesis vitamin K and vitamin B complex . d. They also help in food digestion and absorption. 2. Haemophilus influenzae- size-0.25x1.2µm. Interesting features a. The most common type of disease caused by Haemophilus influenzae type b(Hib) are pneumonia, meningitis,bactermia, epiglottitis etc. b. They are gram negative, highly pathogenic to human. c. Non-typeable Haemophilus influenzae cause common ear infection in children and bronchitis in adults etc. Fig-Haemophilus influenz
- 7. BACTERIAL CELL SHAPE AND ARRANGEMENT When viewed under light microscope, the most bacteria apper in various types- They are 1. Cocci -Bacteria having spherical or oval in shape are called cocci. a. Monococcus- A single cocci cell arranged in a single plane. Ex- Thiocapsa roscopersicina b. Diplococci – Two cocci cells arranged in a single plane. Ex- Neisseria sp. Fig- Neisseria sp. c. Tetracoccus- Four cocci cells arranged in two different planes. Ex- Merisopedia sp. Fig -Thiocapsa roscopersicina Fig- Merisopedia sp.
- 8. d. Sarcinal arrangement- Eight cocci cells arrange in three different planes. Ex-Sarcina lutea. e. staphylococcus-cluster of bacterial cells arranged in different plane. Ex-Staphylococcus aureus f. Streptococcus- Many bacterial cocci cells are arranged in a linear chain. Ex- Streptococcus sp. 2. Bacilli- The bacteria with rod or elongated cylindrical shape are called bacilli. a. Monobacilli- The bacteria with one bacillus cell arranged in a single plane. Ex- Desulfuromonas acetoxidans. b. Diplobacili- The bacteria with two bacilli cells arranged in a single plane. Ex-Klebsiella pneumoniae. Fig-Sarcina lutea. Fig-Staphylococcus aureus Fig- Streptococcus sp. Fig- Desulfuromonas acetoxidans. Fig-Klebsiella pneumoniae.
- 9. c. Bacilli in cluster- Large number of bacilli cells arranged in different plane. Ex- Streptobacilli sp. d. Bacilli in chain- Many bacilli cells are arranged in a linear chain. Ex- Bacillus anthracis. e. Bacilli in cruciform arrangement- Some bacilli cells are arranged in a cruciform. Ex- Corynebacterium sp. f.Bacilli ina rosette arrangement-Ex- caulobacter sp. 3.Spiral shape-These bacteria are carved, rod or comma shaped with vibriatory motility. Ex-Vibrio cholerae. Fig- Streptobacilli sp. Fig- Bacillus anthracis. Fig- Corynebacterium sp. Fig- caulobacter sp. Fig-Vibrio cholerae.
- 10. 3. Other shape a.Star shape. Ex- Stella sp. are star shape bacteria. d.Coccobacilli-Some bacteria are spherical or slightly elongated known as coccobacilli. Ex-Streptobacillus moniliformis. e. Spirilla-Bacteria with a rigid twisted or helical spiral form are known as spirillia. Ex- Rhodospirillum rubrum. f. Spirochetes - Tightly coiled bacteria with corkscrew shaped, helical, flexible having axial filament. Ex- Spirochetes stenostrepta. Polymorphism- Some bacteria may exhibit variation in there shape and size individually, Known as Polymorphism. Ex- Gonococcus sp. , Bacillus sp. Rhizobium sp show swollen forms in ageing cultures having high salt concentration. Fig-Streptobacillus moniliformis. Fig- Rhodospirillum rubrum. Fig-Spirochetes stenostrepta. Fig-Stella sp
- 11. b. Rectangular bacteria-Haloarcula sp. a genus of halophilic archaea, are rectungular in shape. c. Actinomycetes- Branched, filamentous bacteria resembling to the radiating rays seen in tissue lesions Ex- Nocardia sp. h. Mycoplasma- Lacking cell wall, round or oval, small and pleomorphic in nature. Ex- Mycoplasma genitalium. e. Appendaged bacteria – posses extension of their cells as long tubes or stalks. Ex-Rhodospirillum rubrum. Fig-Haloarcula sp Fig-Nocardia sp Fig- Mycoplasma genitalium. Fig- Rhodospirillum rubrum.
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