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Bacteria do not contain organelles in the same sense as eukaryotes. Instead, the chromosome and perhaps ribosomes are the only easily observable intracellular structures found in all bacteria. There do exist, however, specialized groups of bacteria that contain more complex intracellular structures, some of which are discussed below.
The second chromosome has also been called a chromid, in that they have similar codon usage to the chromosome, are essential to life like the main chromosome, but has plasmid-type elements such as the origin of replication. Many other sequenced Paracoccus also have chromids. [25] Vibrio have two circular chromosomes.
Most bacteria have not been characterised and there are many species that cannot be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology. Like all animals, humans carry vast numbers (approximately 10 13 to 10 14) of bacteria. [3] Most are in the gut, though there are many on the skin.
The complex contains a single circular chromosome, a cyclic, double-stranded molecule of stable chromosomal DNA, in contrast to the multiple linear, compact, highly organized chromosomes found in eukaryotic cells. [55] In addition, many important genes of prokaryotes are stored in separate circular DNA structures called plasmids. [56]
B. anthracis has a single chromosome which is a circular, 5,227,293-bp DNA molecule. [10] It also has two circular, extrachromosomal, double-stranded DNA plasmids, pXO1 and pXO2. Both the pXO1 and pXO2 plasmids are required for full virulence and represent two distinct plasmid families. [11]
Their genome is usually a circular bacterial chromosome – a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. These plasmids can be transferred between cells through bacterial conjugation. Bacteria have an enclosing cell wall, which provides strength and rigidity
V. cholerae has two circular chromosomes. One chromosomes produces the cholera toxin (CT), a protein that causes profuse, watery diarrhea (known as "rice-water stool"). [5] But the DNA does not directly code for the toxin as the genes for cholera toxin are carried by CTXphi (CTXφ), a temperate bacteriophage (virus). The virus only produces the ...
Spiral bacteria are another major bacterial cell morphology. [2] [30] [31] [32] Spiral bacteria can be sub-classified as spirilla, spirochetes, or vibrios based on the number of twists per cell, cell thickness, cell flexibility, and motility. [33] Bacteria are known to evolve specific traits to survive in their ideal environment. [34]