Question

What are the three groups of bacteria ? Describe their structure.

Answer 1

Bacteria:

1. Bacteria belong to the kingdom Monera.
2. They are unicellular organisms without a well-defined nucleus and membrane-bound organelles. Thus, they are prokaryotes.
3. The cell wall present is composed of peptidoglycan.
4. They can be autotrophs, and make their own food.
5. They can be heterotrophs, and depend on others' food.
6. Examples: Streptococcus pneumonia, Mycobacterium tuberculosis, Salmonella, etc.

Based on their shape they are divided into several groups:

1. Cocci: These bacteria are spherical in shape. They live as a single cell (monococcus), in a group of two (diplococcus), as a long-chain (streptococcus), or in bunches (staphylococcus). Examples: Streptococcus pneumonia, Neisseria gonorrhoeae, etc.
2. Bacilli: Bacteria that are rod-shaped with or without flagella. They generally live as a single cell or in chains. Examples: Lactobacillus, Bacillus and Pseudomonas.
3. Spirilla: Bacteria that are spiral-shaped. They live alone. They help increase the fertility of the soil. Example: Treponema, and Campylobacter.
4. Vibrios: Bacteria that are short, and curved like a common. Example: Vibrio cholerae.