WHAT IS BACTERIA PLEASE EXPLAIN
Bacteria are microscopic unicellular micro-organisms having circular DNA in a region called nucleoid as well as few organelles of which none are surrounded by an envelope. They are prokaryotes. Only some bacteria cause diseases while others are useful in nature.
They are also very versatile organisms, surviving in extremely inhospitable conditions. Such organisms are called extremophiles. Extremophiles are further categorised into various types based on the types of environments they inhabit:
- Thermophiles
- Acidophiles
- Alkaliphiles
- Osmophiles
- Barophiles
- Cryophiles
Another fascinating feature of bacteria is their protective cell wall, which is made up of a special protein called peptidoglycan. This particular protein isn’t found anywhere else in nature except in the cell walls of bacteria.
But few of them are devoid of this cell wall, and others have a third protection layer called capsule. On the outer layer, one or more flagella or pili is attached, and it functions as a locomotory organ. Pili can also help certain bacteria to attach themselves to the host’s cells. They do not contain any cell organelle as in animal or plant cell except for ribosomes.
Ribosomes are the sites of protein synthesis. In addition to this DNA, they have an extra circular DNA called plasmid. These plasmids make some strains of bacteria resistant to antibiotics.
Bacteria can be either autotrophic or heterotrophic. The autotrophic bacteria are capable of preparing their own food while the heterotrophic bacteria depend on other sources such as soil, plants and animals for their food. Some bacteria are parasites growing on plants and animals and cause diseases in them. Some bacteria are saprophytic and breakdown the dead plants and animals found in the soil and derive nutrients from them. These saprophytic bacteria help in increasing the fertility of the soil.
Beside performing asexual methods of reproduction, they also perform sexual reproduction (during unfavourable conditions), which is a way of DNA transfer from one bacterium to another. So, bacterial cells can be called to meet while performing sexual methods of reproduction.
Three modes of sexual reproduction are:
· Transformation
· Transduction
· Conjugation (exchange of genetic materials within two cells which are in direct contact with each other or by forming a temporary bridge like connection between two cells).