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Bacterial cell


Structure and function of cell organelles in bacterial cells

The bacterial cell belongs to the archaea to the prokaryotes.

Structure of a bacterial cell

Bakterienchromosom: The bacterial chromosome is a self-contained and up to 1.5mm long DNA molecule. Since bacteria have no nucleus, their DNA floats freely in the cytoplasm of the bacterial cell. Similar to the nucleus of eukaryotes, the place where the bacterial chromosome swims in the cytoplasm is also called the core equivalent.
cytoplasmThe cytoplasm includes on the one hand the cytosol, ie the fluids within the cell, and on the other hand all cell organelles (bacterial chromosome, plasmids, ribosomes, etc.) resident there. Incidentally, the cytoplasm is often equated with the cytosol. Water is the major constituent of the cytosol with about 70-80%, followed by proteins with about 20%.
flagellum: threadlike and tortuous flagellin protein strands to move the bacterial cell. Under ATP consumption, the flagellas operate much like a rotating propeller. The number of flagella varies depending on the bacterial species, varies between 1 and 12+. In eukaryotes, analogous organs of locomotion are not flagellum but scourges.
glycocalyx: Enveloping film of polysaccharides (also known as mucous membrane) that protects the bacterial cell from dehydration and hostile bacteria.
Mesosome: Invaginations on the cell membrane. The resulting space can be used by the bacterial cell for special metabolic processes. However, the mesosomes are no longer considered cell organelles today. Some scientists even question their existence.
Pili: cell processes with adhesion function originating from the cell wall (Latin adhaerere = adherence). With the pili (singular = pilus) bacterial cells can attach themselves to other cells or food.
plasma membrane: The plasma membrane or cell membrane, limits the cell to the outside. Because of their semipermeability (permeable, but only for certain molecules), a mass transfer between the outside and inside of the bacterial cell can still occur.
plasmid: small, self-replicating, circular DNA molecules with additional genetic information. Compared with the bacterial chromosome, there are usually no directly important genetic information on the plasmids, but rather resistance genes that only become important for the bacterial cell under certain circumstances. (for example against antibiotics or toxic substances). Plasmids can be exchanged and spread among bacteria.
ribosomes: consist of a complex of RNA (ribonucleic acid) and proteins. At the ribosomes, translation is an important step in protein biosynthesis in which the mRNA is translated into amino acid chains. Bacterial ribosomes (70S) are smaller than the ribosomes of eukaryotic cells (80S) and also occur 10x less frequently (about 10,000 ribosomes in a protozytic cell).
cell wall: Enveloping Protection from Peptidoglycans (Murein). The cell wall basically fulfills two important functions: on the one hand it maintains the shape of the cell and on the other it protects the cell from external influences (for example bacteriophages or unfavorable environmental conditions).