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Prokaryotes March 24, 2010 Prokaryotes Mar 236:22 PM Mar 248:05 AM Mar 236:36 PM 1 Prokaryotes March 24, 2010 Classification based on: • shape • Structure of cell wall • Source of food/energy Mar 236:34 PM SHA PE Cocci round (singular is coccus) Bacilli rodshaped (singular is bacillus) Spirilli spiral shaped (singular is spirillum) Mar 236:36 PM s n ter t a P th ow Diplo Gr Staphylo ... grows in clusters (like grapes) ... grows in pairs Strepto ... grows in chains Mar 236:43 PM 2 Prokaryotes ss Gue March 24, 2010 ! Who Streptococcus mutans the bacteria that causes tooth decay by using the sugars we eat. The byproduct of the sugar consumption is a acid that eats away at our enamel, causing cavities and tooth decay Staphylococcus aureus the bacteria found on about 1/3 of our skin. can cause minor infections of the skin or serious illness such as pneumonia. Mar 236:52 PM Two Main Membrane Structures gram negative gram positive Gram staining is a process developed by Hans Gram in which the cell wall is stained purple. The purple attaches to the peptidoglycan component of the cell wall. Gram positive cells show up purple while gram negative cells appear pink (becuase they do have a thin layer of peptidoglycan between the cytoplasmic membrane and the outer membrane! Mar 237:39 PM Is this one bacteria specimen or two different species? Mar 237:46 PM 3 Prokaryotes March 24, 2010 Still look the same? Escherichia coli Bacillus anthracis Mar 237:51 PM Nutrition Photoautotrophs receive their energy from the sunlight and their carbon source is CO2 Example: Cyanobacteria Photoheterotrophs receive their energy from the sunlight and their carbon source is organic carbon compounds (ex. carbohydrates, fatty acids and alcohols) Example: Purple nonsulfur bacteria Chemoautotroph obtain the carbon and energy required for life processes from breaking apart inorganic compounds Example: Nitrobacter Chemoheterotrophs Both the energy and carbon source comes from organic matter. Example: Escherichia coli Mar 237:59 PM R E P R O D U C T I O N B I N A R Y F I S S I O N Mar 238:25 PM 4 Prokaryotes March 24, 2010 Conjugation A method of genetic recombination in bacteria Involves the exchange of some or all of a bacteria's genetic code with another individual Cells become linked with a pilus a long tubelike structure Binary fission then occurs and then daughter cells are genetically different from the mother cell was prior to the genetic exchange Mar 238:28 PM Plasmids Small loops of DNA that are separate from the main chromosome. Also genetically different from the main chromosome and can range in size from one gene to many genes. Plasmids can be transferred from one cell to another during conjugation. Used in recombinant DNA technology that can give new traits to an organism. Ex. cloning the gene for the production of insulin in humans. Mar 238:32 PM Endospores When conditions are unfavorable to the bacteria, the organism can form an endospore. The endspore contains the DNA and a small amount of the cytoplasm. While the bacteria is in the endospore phase, the organism does not grow or reproduce. They are extremely resilant to extreme weather conditions including temperature and water availability. When the conditions become favorable again the endospore loses its protective coat and the bacteria begins to grow and divide again. Mar 239:22 PM 5 Prokaryotes March 24, 2010 Bacteria and Us! Bacteria help us break down compounds that cannot be broken down by enzymes. Ex. Beans and cabbage contain sugars that are too big to enter our cells, but we cannot break them down into more manageable sizes. So, bacteria help us do this and the by product of them breaking down the sugar is methane gas...hence the... Mar 239:34 PM A N T I B I O T I C S The resistant bacteria are called MRSA, or Methicillin Resistant Staphylococcus aureus, or VRSA, Vancomysin Resistant Staphylococcus aureus, depending on which antibiotic the S. aureus is resistant to. VRSA is a stronger resistance than MRSA; there has been less cases of VRSA. http://www.youtube.com/watch?v=CLevnx6dZ3E Mar 2310:24 PM Bacteria and the Environment Cyanobacteria produce oxygen for their environment through photosynthesis. Also form the bottom of the food chain, providing food for larger species above them in the food chain. Some species of cyanobacteria fix nitrogen for their environment. Chemoheterotrophs break down organic material, helping the nutrients that individual used reenter their cycle...Ex. Carbon, hydrogen, etc... Chemoheterotrophs such as sulfatereducing bacteria help convert sulfur from a form that is not usable by organisms to a usable form by breaking down hydrogen sulfide. Mar 248:21 PM 6