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Transcript
World of Microbes Microbes <my-crobes> are everywhere. There are more of them on a person's hand than there are people on the entire planet! We couldn't digest food without them—animals couldn't, either. Without microbes, plants couldn't grow, garbage wouldn't decay and there would be a lot less oxygen to breathe. In fact, without these invisible companions, our planet wouldn't survive as we know it! Microbe is a term for tiny creatures that individually are too small to be seen with the unaided eye. Include bacteria, protists, archaebacteria, *viruses Pyrodictium E. coli amoeba Type A flu virus How Small Is a Microbe? If a virus is a baseball Then a pitcher’s mound is a bacteria Then ONE cell of your body is a baseball field Where Do Microbes Live? soil, water and air; in animals, plants, rocks and even us! Bacteria on a rock from Mars Bacteria on teeth How Do We See Them? Light microscope Electron Microscope Bacteria www.spacedaily.com Kingdom: Monera Prokaryotes (pro – carry – oats) Does not have a nucleus Unicellular One-celled Come in different shapes 3 Basic Shapes of Bacteria Bacillus (buh – sill – us) Rod or stick shaped Escherichia coli or E.coli (found in the intestines of mammals) Salmonella typhi (causes typhoid fever and food poisoning) Bacillus infernos Anthrax 3 Basic Shapes of Bacteria Cocci (cox – eye) Round shaped Streptococcus (strep throat) Staphylococci (responsible for "staph" infections and gangrene) 3 Basic Shapes of Bacteria Spirillum (spy – rill – um) Corkscrew shaped Treponema pallidumcholera (syphilis) Borrelia burgdorferi (Lyme disease) Important Structures of a Bacteria Cytoplasm Jelly-like material inside the cell membrane DNA single strand that is not enclosed in a nucleus Free floating in the cytoplasm Contains the genes Eukaryote Cell’s DNA Flagella long, whip-like structure that propels (moves) the bacteria Pili hair-like extensions that help a bacterium stick to a surface Allows exchange of DNA between 2 bacteria Plasma Membrane Surrounds the cell Regulates what enters/leaves the cell Cell Wall Surrounds the plasma membrane Gives the cell its shape Common characteristic with a plant cell Plant Cell : Cell Wall Capsule Surrounds the cell wall Bacteria with a capsule is more likely to cause diseases How a Bacteria Reproduces Itself Binary Fission (bye – nair – ee – fish –un) Bacteria usually reproduce by simply dividing in two. Each new bacterium is a clone of the original—they each contain a copy of the same DNA. If conditions are just right, one bacterium could become a BILLION (1,000,000,000) bacteria in just 10 hours through binary fission! How a Bacteria Reproduces Itself Conjugation One bacterium reaches out to another using a thread-like structure called a pilus and transfers part of its DNA. Beneficial Bacteria Lactobacillus acidophilus (lack-toe-bah-sill-us acid-offill-us): Turns milk into yogurt Beneficial Bacteria Streptomyces (strep-toe-my-seas): soil bacteria wanted for making streptomycin, an antibiotic used to treat infections. Beneficial Bacteria Escherichia coli (Esh-er-ish-e-ah coal-eye): One of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day. Harmful Bacteria Streptococcus pyogenes Strep throat Harmful Bacteria Clostridium tetani tetanus Harmful Bacteria Bacillus anthracis anthrax World History and Bacteria Anton van Leeuwenhoek Robert Hooke Disproved spontaneous generation Rabies vaccine Pasteurization Joseph Lister Developed vaccine against smallpox Louis Pasteur Observed cork cells Coined the term “cell” Edward Jenner Built microscopes Introduced people to the world of microbes Introduced aseptic techniques Robert Koch Developed ways to grow bacteria Koch’s Postulates Viruses What exactly is a virus? When is a life form not a life form? When it's a virus. Viruses are strange things that straddle the fence between living and non-living. On the one hand, if they're floating around in the air or sitting on a doorknob. They're about as alive as a rock. But if they come into contact with a suitable plant, animal or bacterial cell, they spring into action. They infect and take over the cell like pirates hijacking a ship. Viruses are not classified into a kingdom because…. They are not alive until they find a suitable host cell. On their own they….. can’t make their own food can’t reproduce on their own can’t undergo metabolic processes Obligate intracellular parasites Genomic Nucleic Acid Viruses contain either DNA or RNA but not both DNA or RNA can be double stranded or single stranded Some viruses are enveloped Made of lipids, proteins Can be disrupted by: acid, detergents, drying, heating Must stay wet Bacteriophage: virus that infects a bacteria Structures of a Bacteriophage Capsid: contains genetic material and is made of units called capsomeres Structures of a Bacteriophage Tail sheath Contracts to allow genetic material to be “injected” into the bacteria Structures of a Bacteriophage Tail Fibers Allows phage to attach to bacteria Pins Punctures the bacterial wall to allow injection of viral genetic material How Do Viruses Reproduce? Lytic cycle Lyses (destroys) the host cell Involves five steps It takes 30-35 minutes from the time of viral attachment to the releasing of new viruses 250 – 300 new viruses per bacteria Five Steps of Lytic Cycle Attachment Penetration Viral DNA or RNA makes new virus parts inside the host cell Assembly Viral DNA or RNA enters the host cell’s cytoplasm Replication Virus attaches to host cell wall New virus parts are assembled into new viruses Release Lytic enzymes destroy the host cell and new viruses are released T4 Bacteriophage infecting E. coli Attachment or adsorption Penetration Replication Assembly Release How Do Viruses Reproduce? Lysogenic Cycle Viral DNA/RNA combines with host cell DNA Replicates when the host cell replicates Under certain conditions it will revert to the lytic cycle Involves 4 steps Four Steps in the Lysogenic Cycle Attachment Penetration Viral DNA/RNA enters the host cell’s cytoplasm Integration Virus attaches to host cell wall Viral DNA/RNA combines with the host’s DNA Replication Host cell replicates it’s DNA along with the viral DNA Attachment Penetration Integration and Replication Beneficial Viruses Discovery of the role of mRNA in protein synthesis was because of studies with E. coli infected with a bacteriophage Used in DNA cloning Harmful Viruses HIV-retrovirus Rabies - rhabdoviruses Herpes (Greek for “to creep”)