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Chapter 6
Growth & Culturing of Bacteria
| Question | Answer |
|---|---|
| Obligate Aerobes | Organisms that require oxygen to live Have the enzymes to breakdown oxygen. |
| Obligate Anaerobes | Organisms that are unable to use molecular oxygen for energy-yielding reactions and can be harmed by the presence of oxygen. Lack the enzymes to degrade toxic forms of oxygen. |
| Superoxide | Toxic form of oxygen |
| How Obligate Anaerobes produce energy? | Through a process called anaerobic respiration or a primitive anaerobic process called fermentation. |
| Fastidious | An organism that have special nutritional needs can be difficult to meet in the laboratory. |
| Microaerophiles | Although these bacteria are aerobes, they grow best under conditions of a small amount of free oxygen. |
| Capnophiles | Carbon dioxide-loving bacteria grow best under conditions of low oxygen and high carbon dioxide concentration. |
| Facultative Anaerobes | Are aerobic bacteria that have retained the ability to grow in the absence of oxygen. They can use oxygen when it is present but are able to shift to anaerobic metabolism when oxygen is absent. |
| Aerotolerant Anaerobes | Can survive in the presence of oxygen but do not use it in their metabolism. |
| Superoxides | O2 radical that is a highly reactive and toxic form of oxygen. Formed during incomplete reduction of oxygen in aerobic and anaerobic respiration. |
| Superoxide Dismutase | An enzyme that converts superoxide to molecular oxygen (O2) and toxic H2O2. |
| Catalase | An enzyme that converts toxic H2O2 to H2O and molecular oxygen O2 |
| Barophiles | Organisms that live under extreme pressure. Their membranes and enzymes depend on this pressure to maintain their 3D functional shape |
| Isotonic | Equal concentrations of solute inside and outside the cell. |
| Hypotonic | Low osmotic pressure; for example a cell suspended in distilled water; water tends to enter the cell and can lyse the cell especially if the cell wall is weakened. Cells swell and burst. |
| Hypertonic | High osmotic pressure; for example a cell suspended in high salt or sugar concentration; the water moves out of the cell and growth is inhibited. Cells shrivel and shrink. Can be used to preserve foods. |
| Halophiles | Some bacteria can tolerate high salt concentrations and resist the effect of the high osmotic pressure and continue to grow. |
| Radiation | Gamma and UV light can mutate DNA or even kill organisms |
| Carbon Sources - Nutritional Factors | Used as an energy source - synthesize cell components |
| Nitrogen Sources - Nutritional Factors | needed to synthesize enzymes, other proteins and nucleic acids |
| Vitamins - Nutritional Factors | Used as a co-enzyme, many bacteria make their own |
| Nutritional Complexity - Nutritional Factors | Lack of a single enzyme can render an organism incapable of synthesizing a specific substance |
| Extracellular enzymes | synthesized in the cell but crosses the cell membrane to act in the cells immediate environment (gram positive bacilli). |
| Periplasmic enzymes | Act in the periplasmic space (gram negative). |
| Endoenzymes | Enzymes that act within the cell. |
| Axial Nucleoid - Endospore Formation | DNA replicates and two chromosomes split |
| Core - Endospore Formation | Made up of RNA + protein which gather around the chromosome that split. It is the living part of the cell. |
| Endospore septum - - Endospore Formation | Made up of a cell membrane and is the first layer and eventually wraps around for a double membrane which produces peptigolgycon. |
| Cortex - Endospore Formation | Lamenated, protects the DNA that is still inside the core. |
| Dipicolinic acid - Endospore Formation | Found inside the cortex and gives the cortex heat resistance. |
| Spore Coat - Endospore Formation | Keritein like which is belived to provide additional protection. Help resist chemicals. |
| Exosporium - Endospore Formation | Lipid around the cortex, unknown what it is for. |
| Activation - Germination | When favorable conditions return. |
| Germination proper - Germination | When water is needed. |
| Outgrowth - Germination | When nutritional requirements have been met. |
| Streak Plate Method | Means of isolating a colony, method of diluting out the colonies. |
| Pour Plate Method | Dilutions of original organism (TSB). Reduces the numbers. |
| Synthetic Medium | prepared in the lab and sometimes prepared with almost exact specifications or close to it. |
| Defined Synthetic Medium | A medium in which the exact chemical composition is known. |
| Complex Medium | A medium in which the exact chemical composition varies from batch to batch. The use of extracts from soybeans, beef, and yeast will provide a source of energy, carbon, nitrogen, sulfur, phosphorus, vitamins and minerals. |
| Enriched | Some enriching substances are added to the medium. An example of enriching substance is blood. |
| Selective | Addition of substances to suppress the growth of unwanted bacteria while allowing the desired bacteria to grow. |
| Differential | Addition of substances to distinguish between organisms growing on the medium. |
| Biochemical Test Media | A variety of media are available to test for a particular biochemical activity of the inoculated organism. The medium will have a substrate added to it and usually some indicator to detect the end products. |
| Reducing Media | These are used to grow anaerobes. They have chemicals added to the media to remove oxygen and usually have an oxygen sensitive indicator to show whether oxygen has been completely removed. |
Created by:
sbiosweitz
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