MICR 3050 Week 1 Lecture Notes
MICR 3050 Week 1 Lecture Notes MICR 3050
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This 3 page Class Notes was uploaded by Toni Franken on Sunday January 10, 2016. The Class Notes belongs to MICR 3050 at Clemson University taught by Dr. Whitehead in Spring 2016. Since its upload, it has received 75 views. For similar materials see General Microbiology in Microbiology at Clemson University.
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Date Created: 01/10/16
MICR 3050 – Notes Set 1, 01/08/2016 Dr. Whitehead, Clemson University Chapter 1, Intro to Microbiology Party Fact of the Day: Oral microbiota: The microbes that live in your mouth. There are at least 700 species that are commonly found in a healthy human mouth. Mouth to mouth contact is often found in animal species for feeding purposes, for mate selection, etc. However, “intimate kissing” (French kissing) – done only in the human species, and spreads billions of microbes in one exchange. Chapter 1: What are Microorganisms: Organisms and acellular entities too small to be clearly seen by the unaided eye. They are generally less than or equal to 1mm in diameter, and often unicellular. Acellular (A meaning without, so without cells) entities are like viruses (debates on if they actually live). There are exceptions to every statement. Exceptions: Mold on bread – large enough to see with the naked eye. Some photosynthetic microbes, also. Some new, large microbes have been discovered in the recent years as well. We also have a few organisms that are multicellular (but less complex) that are considered microorganisms. Everything is divided into cellular or acellular. Cellular entities (3 domains of life: bacteria, archaea, eukarya; Protists/Fungi fall into Eukarya) are definitely living. Acellular are often debated as far as being living or not. (viruses and prions most common; viroids (sort of viruses) – these categories are not included in the 3 domains of life). Microorganisms are important for various reasons. They’re the most populous and diverse group of organisms (estimated 5 x 10^30). They’re found everywhere except possibly a healthy human brain. They recycle elements (such as nitrogen fixing, carbon recycling, etc). They’re a source of nutrients for some organisms, and some carry out photosynthesis (although slightly differently than plants). Most of them are beneficial or benign, and a very few commonly cause human disease. They influence all living things, and they’re great models for experimental study due to quick generation turn around, and is much less likely to spark controversy. Types of Microbial Cells: Prokaryotic cells: The term prokaryote technically means without a membrane bound nucleus, and tend to not have membrane bound organelles. It’s a controversial term because it tells you what an organism is NOT, but not what it IS. There are also exceptions to the term, such as prokaryotes that have membrane bound nuclei or organelles, but are technically classified as prokaryotes, or some prokaryotes that are larger and more complex than most. Prokaryotes typically contain genetic material in a nucleoid, a tangled mass in the center of the cell. They are capable of performing the same functions as eukaryotes, just in different ways. Eukaryotic cells: have a membrane bound nucleus, and tend to be larger and more complex. Often talking about protists and fungi. Acellular microbes: NOT considered cellular, and therefore do not fall into this category. See the following for more details. Acellular Infectious Agents: Virus: Viruses must have some type of protein coat on the outside shell, and must have some type of nucleic acid (genetic information) in the core. Genetic information in viruses is much more varied than in cellular organisms – can have single or double stranded DNA or RNA, could have + or – RNA. Viruses HAVE to have a host cell to replicate. There’s a debate about if viruses are living or not, because if it can’t reproduce on its own, is it truly alive? Influenza virus has spikes on the outside of it. There’s a whole subset of viruses that prey only on bacteria (bacteriophages), and a whole subset that are involved in cancer development in humans. Tend to be incredibly small, where you may only be able to see them with an electron microscope. Next in size would be prokaryotic cells, followed by eukaryotic. Viroids and Virusoids: By definition, “less than” viruses. They are typically RNA based. They tend to infect animals and plants. Prions: Infectious proteins: “mad cow disease,” Scrapies, Kuru, etc. Prion diseases are all 100% fatal. Classification: Universal Phylogenetic Tree The Universal Phylogenic Tree is a 3 domain system, developed by Carl Woess, based on a comparison of the DNA encoding small subunit ribosomal RNA (SSU RNA). Ribosomes are the machinery to help in translation of genetic material. A Ribosome has a small subunit that contains SSU RNA. 16S rRNA is in bacteria. 18S is found in eukaryotes. In each organism’s SSU RNA, there is a gene related to the “molecular clock,” which is used to predict where organisms stand in the evolutionary line. All organisms have the SSU rRNA in some form. This allows us to compare them all. On the Universal Tree of Life, the Eukaryotic Crown Species of Animals, Fungi, and Plants are only a very small number of organisms. The vast majority fall into microorganisms. The base organism of the entire tree is called LUCA; Last Universal Common Ancestor. Archea and Bacteria are very similar to each other, and were originally thought to be close in evolutionary development. However, SSU rRNA show that bacteria have evolved separately from Archea and Eukarya. The basic process of developing the Universal Phylogenic tree is to take cells, isolate and extract DNA, and use PCR to make thousands of copies of a particular portion of the SSU rRNA, and get the gene sequence. They then compare the organisms’ gene sequences, and look for the differences. The more differences there are, the less related those organisms are from an evolutionary standpoint. Domain: Bacteria This domain contains only prokaryotes. They are usually single celled, but some bacteria work in groups and cooperate with each other. Also have a pheonmena in bacteria where there are ‘cheaters” that don’t do what they’re supposed to. Almost all of them are surrounded with a cell wall made of peptidoglycan, and have a cell membrane under it. They’re abundant everywhere. Soil, water, air, on/in other organisms. Some live in incredibly extreme environments (NASA clean rooms). Domain: Archaea Prokaryotes: usually single celled. Distinct SSU RNA sequences. They’re quite different from bacteria evolutionarily. They don’t have peptidoglycan in their cell walls, and their cell membrane contain particular lipids. Some have unusual metabolic characteristics; methanogens = archaea that make methane. Methanogens are found in about 2/3 of the human population’s intestines. Many of them live in extreme environments and thrive. Get protection from their unique membrane lipids. Some can survive at 110 degrees C. Can survive in 9% Sodium Chloride, where sea water is only at .9% sodium chloride. Domain: Eukarya Protists: typically unicellular, but generally larger than members of Bacteria and Archea. No peptidoglycan. Algae, protozoa, slime molds, and water molds. Malaria – active agent is a protest. River Blindness. Giardia. Fungi: These organisms run the whole range from unicellular yeasts to multicellular mushrooms and larger fungi. Argument that the single biggest living thing is a fungus right now. Go from relatively simple and relatively complex. Microbiology mostly focuses on yeasts and molds: wine/beer production.
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