Question

What are the 2 main types of bacteria?

Answer 1

Bacteria and its types:

1. Bacteria are unicellular organisms belonging to the prokaryotic group where the organisms lack a few organelles and a true nucleus.
2. On the outer layer, one or more flagella or pili are attached, and it functions as a locomotory organ.
3. They do not contain any cell organelles as in animal or plant cells, except for ribosomes.
4. Bacteria may be roughly divided into gram-positive bacteria and gram-negative bacteria based on the two different types of cell walls they have
5. The names come from how cells respond to the Gram stain, an established technique for identifying different bacterial species.
6. In this technique, bacteria are stained with a weakly alkaline solution of crystal violet.
7. Then bacterial smear is treated with an aq. solution of iodine.
8. Extra stain is washed with acetone/water/alcohol.

Gram-positive bacteria:

1. Bacteria that retain the purple stain are called gram-positive bacteria.
2. They contain a higher amount of peptidoglycan in their cell wall.
3. A single-layered, smooth cell wall is present.
4. The thickness of the cell wall is 20 to 80 nanometres.
5. In gram-positive bacteria teichoic acids are present.
6. Porins are absent in these bacteria.
7. These are more susceptible to antibiotics.
8. Generally, flagella are not found.
9. They produce spores.
10. Examples: Diplococcus pneumonae, Staphylococcus aureus.

Gram-negative bacteria:

1. Bacteria that become decolorized and did not attain any stain are called gram-negative bacteria.
2. A lesser amount of peptidoglycan is present in their cell wall.
3. A double-layered, wavy cell-wall is present.
4. The thickness of the cell wall is 8 to 10 nanometres.
5. Absence of teichoic acids in these bacteria.
6. Outer membrane of bacteria have porins.
7. These are more resistant to antibiotics.
8. Generally, flagella are found.
9. They do not produce spores.
10. Examples: E.coli, Vibriocholerae.