Microbiology

Microbiology Study Guide

bacteria. Once the full name, Staphylococcus aurens, as S. aurens when used later. Place of Microorganisms in the World The major groups of microorganisms are bacteria, fungi, protozoa, and viruses. All microorganisms are very small . Most microbes are only one cell. Viruses do not have cells and are dead outside a living host. Viruses become alive inside a host. All microbes range in size from small viruses (20 nm) to protozoans (>5mm). Differences between Prokaryotes and Eukaryotes Prokaryotic organisms (before nucleus) have no true nucleus and no internal membrane-bound structures (organelles). This group includes bacteria and archaea. Eukaryotic organisms (true nucleus) do have true nucleus and do have internal membrane-bound structures (organelles). This group includes organisms like protistans, fungi, animals (including helminths or worms), and plants. Prokaryotes (Prokaryotae): Bacteria, Cyanobacteria, and Archaeobacteria Bacteria (single-bacterium) are single celled with spherical, rod, or spiral shapes. These organisms have no nucleus and no membrane-enclosed intracellular structures (no organelles). They have a cell wall that contains a protein-carbohydrate complex. Bacteria replicate by a process known as binary fusion, in which they divide into two equal cells. Many of these organisms absorb nutrients from their environment, while some make their own nutrients using photosynthesis or other synthetic processes. Widely distributed in nature, bacteria can be stationary or mobile and certain species can cause human and animal diseases (pathogenic bacteria). Cyanobacteria is a type of bacteria that get their energy from photosynthesis. They are called “cyanobacteria” because of their color (cyan blue). Archaeobacteria are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon (sometimes spelled “archeon”). They have no cell nucleus or any other membrane-bound organelles within their cells. They also have no cell wall and no membrane-bound organelles. Eukaryotes (Eukaryotae): Protozoa, Algae, and Fungi Protozoa are a diverse group of single-cell eukaryotic organisms, many of which are motile. Protozoa are defined as single-cell protists with animal like movement. They move through the use of flagella, cilia, or pseudo-pods. Many are parasites but they can live as single entities. Simple algae (protophyta) are single-celled protists (eukaryotic organisms) that have plant-like behavior (get their energy from photosynthesis). Simple algae grow in fish tanks, pools, and ponds. Fungi are unicellular or multi-cellular (yeasts are unicellular, molds are multi-cellular) heterotrophs (depending on outside energy sources). They are scavenger; they live off dead matter and thus, decompose it. Viruses are dead on the outside of host cells and are alive on the inside of host cells. A virus is a small has been mentioned, it can then be abbreviated

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