BRAINCAKEAlternative Classification of Bacteria
As well as the Gram stain, bacteria can be classified by their shape and by their respiratory requirements.
Shape. The main shapes seen under the microscope are:
• cocci (singular coccus): spherical, e.g. Staphylococcus
• bacilli (singular bacillus): rod-shaped, e.g. E. coli, Salmonella
• spirilla (singular spirillum): spiral or corkscrew-shaped, e.g. Treponema (spirochaetes)
• vibrios: comma-shaped, e.g. Vibrio cholerae
The way cells stay together after dividing is also useful. Staphylo- means grape-like clusters (Staphylococcus), strepto- means chains (Streptococcus) and diplo- means pairs (Diplococcus).
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Key terms in this lesson
- anaerobic respiration
- Respiration that takes place without oxygen, producing ATP less efficiently than aerobic respiration and yielding products such as lactate or ethanol.
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