Bacteria (spheres, rods, spirals)

Bacteria (spheres, rods, spirals)

Bacteria occur in a wide range of shapes, including spheres, rods and spirals.



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Cell wall



Bacteria are single-celled, prokaryotic microorganisms. They can be found everywhere on the planet; the ancestors of modern bacteria appeared on Earth about 3.5 billion years ago.

The cytoplasm forms the main mass of a bacterium cell. It contains the genetic material, that is, the ring-shaped DNA. Unlike in eukaryotes, proteins are not attached to the DNA in prokaryotes. The cytoplasm is enclosed in the cell membrane.

All bacteria have a cell wall. It is tough and rigid, and it is made from proteins and polysaccharides. It provides the cells with structural support and protection.

Outside the cell wall is the capsule, which is made mainly from polysaccharides. It protects the cell and is responsible for the diseases caused by some bacteria in the host organism.
Some bacteria are capable of active locomotion through the use of their flagella.

Bacteria have an exceptional ability to adapt and reproduce, and this is why they are extremely widespread. They are capable of both sexual and asexual reproduction. If they reproduce through binary fission, which is a form of asexual reproduction, it results in a large number of individual bacteria cells.
Bacteria occur in a wide range of shapes, including spheres, rods and spirals.

Spherical bacteria, which are called cocci, can occur as single cells, pairs, chains or clusters. Many bacteria that produce suppurative infections or pneumonia are spherical. Gonorrhea is also caused by cocci.

One group of rod-shaped bacteria are called bacilli. These can be harmless, such as the lactobacilli used in the food industry. Many bacilli cause diseases, like the pathogens of plague, tuberculosis, salmonellosis and tetanus. Escherichia coli, which is commonly found in the human intestinal system, is also a bacillus.

Syphilis, Lyme disease and leptospirosis are caused by spiral-shaped bacteria.

Gram staining is a method of differentiating bacteria into two groups, i.e. Gram negative and Gram positive. The basis of differentiation is that staining produces different results in the cell walls of different types of bacteria because of their different structure. The two types of bacteria react to antibiotics differently, so treating different bacterial infections requires different antibiotics.

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