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Cell Respiration Quiz
Quiz by Marta Johnson
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Bacterial Cell One of the very first organisms to evolve on earth was probably a unicellular organism, like modern bacteria. Ever since then, life has evolved into a multitude of life forms over many millennia. However, we can still trace our ancestry back to this single-celled organism. Bacteria Definition âBacteria are unicellular organisms belonging to the prokaryotic group where the organisms lack a few organelles and a true nucleusâ. Internal Structures ⢠Cytoplasm: A gel-like substance that fills the cell, containing water, enzymes, nutrients, and waste, where metabolic activities occur. ⢠Nucleoid: A region within the cytoplasm that houses the bacterial chromosome, a single, continuous circle of DNA. ⢠Ribosomes: Responsible for synthesizing proteins within the cell. ⢠Plasmids: Small, circular, extra-chromosomal DNA molecules that can provide advantageous traits, such as antibiotic resistance. ⢠Mesosomes: (Optional, less prominent in some views) Folds in the plasma membrane that are believed to be involved in cell division and respiration. Outer Structures & Layers ⢠Cell Wall: A rigid outer layer composed of peptidoglycan that provides structural support, maintains cell shape, and protects against osmotic lysis. Capsule: (Optional) A sticky outer layer of polysaccharide that can help the bacteria adhere to surfaces, protect against phagocytosis by the immune system, and serve as a food reserve. ⢠Plasma Membrane: A selectively permeable barrier that regulates the passage of nutrients and waste products into and out of the cell. Appendages ⢠Flagella: Long, whip-like structures that provide motility, allowing the bacterium to move through its environment. ⢠Pili (and Fimbriae): Hair-like protein appendages. Pili are longer and involved in bacterial conjugation (transfer of genetic material), while the shorter, more numerous fimbriae primarily function in attachment to host cells or surfaces.