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Slideshow on bacteria cells. Includes structure, endospores gram negative and gram positive cell wall structure and other information

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  1. 1. Bacteria
  2. 2. Structure of a Bacterial Cell <ul><li>Plasma Membrane; The plasma membrane is a semi-permeable barrier that separates the inside of a cell from the outside. It is typically made up of phospholipids and proteins. The membrane is used to transport solutes, in the generation of energy and it is the location of several enzyme systems. </li></ul><ul><li>Ribosomes: The ribosomes are used in protein synthesis. They are the site of the translation process of RNA. </li></ul><ul><li>Chromosome: Contains most of the g enetic material of cell </li></ul> and Wikipedia
  3. 3. Endospores <ul><li>Endospores is a non-reproductive structure of a bacteria cell. It is dormant and resilient. </li></ul><ul><li>The endospore is mainly to ensure the survival of a bacteria during environmental stress. Therefore they are resistant to temperature, starvation, ultraviolet radiation, gamma radiation. </li></ul><ul><li>He process of making an endospore is called sporulation and takes approximately eight hours. The DNA is replicated and the cell forms a membrane wall between the replicated DNA and the rest of the cell.The cell is surrounded by the plasma membrane and pinches off leaving the DNA enveloped in a double membrane. At this point it called a forespore. </li></ul><ul><li>Next, what is called a peptidoglycan cortex fors between the two layers enveloping the replicated DNA and the cell adds a spore coat to the forespore. The now fully formed endospore will be released once the surrounding cell is degraded. </li></ul> and wikpedia
  4. 4. Gram Negative Cell Wall Structure <ul><li>The gram negative cell wall has a thin inner wall that is made up of peptidoglycan which is generally 2 to 3 nanometers thick and have 2 to 3 layers of peptidoglycan . The peptidoglycan makes up to approximately 10 to 10% of the cell wall. The outer membrane is a lipid bilayer that is approximately 7 nanometers thick and is made up of proteins, phospholipids, lipoproteins and lipopolysaccharides (also called LPS). Phospholipids are located mainly in the outer membrane’s inner layer, along with the lipoproteins that connect the outer layer and the peptidoglycan. The lipopolysaccharides are found in the outer layer. The LPS portion is also called an endotoxin. The proteins that cover the surface of the outer membrane differ with species and strain of bacteria. </li></ul><ul><li>The peptidoglycan prevents the cell from bursting open from osomotic pressure from an hypotonic environment. The outer membrane is semi-permeable so it helps keep certain enzymes and proteins within the cell while preventing some toxic substances from entering. The LPS is believed to reinforce the cell wall. The membrane also forms vesicles which can fuse with the membrane of other gram negative cells. These vesicles are use to transport substances. </li></ul><ul><li>Many gram negative bacteria are capable of causing disease in an host organism. In Gram Staining they don’t retain the violet colour and appear to be a red/pink colour. </li></ul> and wikipedia
  5. 5. Gram Positive Cell Wall Structure <ul><li>The cell wall of a gram positive is made up of peptidoglycan as the outer layer and a cytoplasmic membrane as the innermost layer with a layer of periplasm. It also often has various external structures such as flagella. 60 to 90% of the cell wall is made up of peptidoglycan. The gram positive cell wall also has teichoic acids and lipoteichoic acids. The teichoic acids are made of polymers of glycerol, phosphates, and a sugar named alcohol ribito and extend through the rest of the cell wall. Lipoteichoic acids are teichoic acids with lipids attached. The outermost surface of the peptidoglycan is studded with proteins. These differ depending on the type of bacteria. </li></ul><ul><li>The peptidoglycan prevents the cell from bursting open from osomotic pressure from an hypotonic environment. The teichoic acids reinforce the cell wall, strengthening it. The surface proteins on the peptidoglycan can function as enzymes and adhesins and on ocassion as i nvasins. An adhesin is a protein that bind specific receptors to the surface of the cell wall and allow the bacteria to form colonies and resist being physically removed while invasins are proteins in the cell wall of various bacteria that allow the bacteria to penetrate other cells. </li></ul> , and wikipedia
  6. 6. Media <ul><li>Bacteria can only grow between certain temperatures and, like most organisms, need nutrients such as sugars and proteins to grow. Exactly what nutrients vary with the type of bacteria. By depriving them of nutrients or placing them in an environment with a temperature that is either too high or low for the bacteria to handle. This is why not all types of bacteria will grow on a single type of media or at the same temperature. So there are different types of media, such as selective media and differential media. </li></ul><ul><li>Selective media are made to stop the growth of certain types of bacteria and encourage the growth of other types. It is possible to change the psychical properties of a selective media such as temperature and pH to make so that only specific organisms can grow under certain conditions. </li></ul><ul><li>Differential media is a media that has a indicator, such as a dye added that result in different chemical reactions during an organisms growth, allowing for easy identification of a bacteria. </li></ul> ,
  7. 7. Limiting Bacteria Growth <ul><li>There are various methods to limit bacterial growth, some involving the physical properties and others using chemicals. The process of limiting the growth of mirco-organisms is called microbiostasis </li></ul><ul><li>One physical procedure is to place the sample in a place of low temperature such as a refrigerator as the cold will generally slow down the bacteria growth. </li></ul><ul><li>The are also drugged referred to as antimicrobial drugs that have a microbistatic effect </li></ul> ,
  8. 8. Antimicrobial Agents <ul><li>Antimicrobial Agents can be effected by various factors such as types. Some micro-organisms are unaffected by some types of agents. Also, the more of the micro-organisms there are, the more antimicrobial agent needed to eliminate them. Typically there is a minimum concentration the agent must reach in order to be effective. </li></ul><ul><li>The period of time an micro-organism is exposed to the agent will have an effect on how many of the micro-organisms will be killed by the agent. </li></ul><ul><li>Generally, the agents are more effective and work at a faster rate at a higher temperature </li></ul>
  9. 9. Cell Transport <ul><li>Cells have various types of methods for transport substances in and out of the membrane. </li></ul><ul><li>Diffusion is the process of molecules passing through the cell wall. The overall movement is from high concentration to a lower concentration. This process is passive and doesn’t require any energy from the cell but instead uses the kinetic energy the molecules already have. Osmosis is simply the diffusion of water. </li></ul><ul><li>Active transport is the term referring to cell transport that requires energy because it goes against the concentration gradient. </li></ul><ul><li>PEP Group Translocation is a multi-component system of active cell transport. It uses the enzymes in the cell membrane and cytoplasm. Bacteria cells typically use it to take in sugar </li></ul>Wikipedia,
  10. 10. Effects of Antibiotics <ul><li>Antibiotics have effects on various cell functions such as pencillians which hinder the synthesis of the cell wall as it is meant to. Antibiotics target normal but vital functions </li></ul><ul><li>The largest group of antibiotics are ones that hinder protein synthesis </li></ul><ul><li>There are organisms which are resistant to types of antibiotics or could develop resistance. For example all strands of Staphylococcus aureus are currently resistant to penicillin but in 1940s and 1950s, penicillin could be used to successfully treat Staphylococcus aureus. </li></ul> , wikipedia