Chapter 56
Microbiology
The microbial world
The Scope of Microbiology
Microbiology studies diverse organisms -- archaea, bacteria, protozoa, algae, fungi, and acellular entities -- nearly all too small to see. Prokaryotic organisms (bacteria and archaea) are single-celled and lack internal membrane structures; eukaryotic organisms contain a true membrane-bound nucleus and organelles. The three domains are Eukarya (algae, fungi, protozoa), Bacteria, and Archaea (extreme environments, not medically important).
Two nonliving but medically significant entities also exist: viruses (which cannot replicate without host cell machinery) and prions (infectious proteins).
Prokaryote vs Eukaryote
Prokaryotes (bacteria) have a single circular chromosome, 70S ribosomes, a peptidoglycan cell wall, no membrane-bound organelles, and divide by binary fission. Eukaryotes (fungi, protozoa) have a true nucleus, 80S ribosomes, and membrane-bound organelles. The 70S vs 80S ribosome difference is the target of many antibiotics.
📖 “Microbiology: archaea, bacteria, protozoa, algae, fungi, acellular entities. Prokaryotes (bacteria/archaea): single-celled, no internal membranes, 70S ribosomes, circular chromosome, binary fission. Eukaryotes: true nucleus, organelles, 80S ribosomes. Domains: Eukarya, Bacteria, Archaea (extreme environments). Viruses/prions: nonliving but medically significant.”