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Bacteria (/ b æ k ˈ t ɪər i ə / ⓘ; sg.: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats.
- Earliest Known Life Forms
Evidence of possibly the oldest forms of life on Earth has...
- Parasitic
A fish parasite, the isopod Cymothoa exigua, replacing the...
- Genetically Modified Bacteria
The use of bacteria to synthesise chymosin also provides a...
- Bacterial cell structure
Bacterial cell structure. A bacterium, despite its...
- Gram-positive bacteria
In bacteriology, gram-positive bacteria are bacteria that...
- Evolution
The evolution of bacteria has progressed over billions of...
- Earliest Known Life Forms
- Reproduction and Gene Transfer
- Shape
- Pathogens
- Extremophiles
- Viruses
- History of Their Classification
- Related Pages
A bacterium reproduces (creates more bacteria) by dividing in halfand creating two "daughter" cells. Each daughter is identical in shape to the parent. Bacteria do not have sexes, but they do transmit DNA by several kinds of horizontal gene transfer. This is how they share resistance to antibiotics from one strain to another. The complete DNA seque...
Bacteria vary widely in size and shape, but in general they are at least ten times larger than viruses. A typical bacterium is about 1 µm (one micrometer) in diameter, so a thousand bacteria lined up would be one millimeter long. There are about five nonillion (5×1030) bacteria on Earth. Bacteria are identified and grouped by their shapes. Bacilli ...
Pathogenicbacteria, the harmful kind, enter the human body from the air, water or food. Once inside, these bacteria attach themselves to or invade specific cells in our respiratory system, digestive tract or in any open wound. There they begin to reproduce and spread while using your body's food and nutrients to give them energy to help them reprod...
Some bacteria are extremophiles. Some microbes thrive inside rocks up to 580 meters below the sea floor under 2.6 kilometers of ocean off the Pacific Northwest of the United States.According to one of the researchers, "You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are."
Viruses were the first and are the most serious enemies of bacteria. Everywhere bacteria are, they get attacked by viruses. The viruses which attack bacteria are called bacteriophages. Something is now known about how bacteria protect themselves against viruses. Some bacteria and most archaea have CRISPR–Cas systems as an adaptive defence against v...
All modern ideas start with the sequence analysis of DNA and RNA. In 1987, Carl Woese, the forerunner of the molecular phylogeny revolution, divided bacteria into 11 divisions based on 16S ribosomal RNA(SSU) sequences: 1. Proteobacteria: Purple bacteria and their relatives 1.1. Alpha subdivision: purple non-sulfur bacteria, rhizobacteria, Agrobacte...
A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells . The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India.
4 days ago · Learn about bacteria, any of a group of microscopic single-celled organisms that live in almost every environment on Earth and have diverse metabolic capabilities. Find out how bacteria differ from animal and plant cells, how they evolved from ancient prokaryotes, and how they are classified into three domains.
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