What are bacterial cells and how are they arranged?
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arrangements based on their planes of division. a. Division in one plane produces either a diplococcus or streptococcus arrangement. b. Division in two planes produces a tetrad arrangement. A tetrad: cocci arranged in squares of 4
d. Division in random planes produces a staphylococcus arrangement. 2. The rod or bacillusTHE BACILLUS:
arrangement.a. bacillus: single bacilli
3. The spiralSpirals come in one of three forms, a vibrio, a spirillum, or a spirochete. a. vibrio: a curved or comma-shaped rod
Trichome-forming, sheathed, stalked, filamentous, square, star-shaped, spindle-shaped, lobed, and pleomorphic.
All cells can be placed into one of two groups: Prokaryotic or Eukaryotic. Prokaryotes tend to be smaller and simpler in structure while Eukaryotes tend to be larger and more complex since they contain membrane-bound organelles (structures that perform specialized jobs within the cell), like the nucleus. Prokaryotes, on the other hand do not contain a nucleus or any other organelles.
Bacterial cells consist of a circular chromosome (genetic information) which is found in the nucleoid region. The cell is filled with cytoplasm (jelly like goo that fills all cells). There are also ribosomes floating around in the cytoplasm (their job is to make protein using the instructions from the DNA). A cell membrane wraps around the cell to control what gets in and out of the cell. A rigid cell wall can be found outside of the membrane to offer support and protection to the cell. Usually there is also some sort of appendage to assist in the movement of the cell. It can be a long, whiplike tail (like on a sperm) called a flagellum, or many small hairlike growths that the cell uses like little oars called cilia.
The layers that surround the prokaryotic cell are referred to collectively as cell envelope. The structure and organization of the cell envelope differs in gram-positive and gram-negative bacteria. The cell envelope of gram-positive cells is relatively simple consisting of 2-3 layers: the cytoplasmic membrane, a thick peptidoglycan layer and some bacteria have an outer layer, either a capsule or an S-layer (slime layer). The cell envelope in gram-negative bacteria is highly complex multilayered structure.
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