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Physical Factors which effect bacterial growth:
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Nutritional Factors which effect bacterial growth:
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Microbiology Quiz #2
Chapters 6-8
| Question | Answer |
|---|---|
| Physical Factors which effect bacterial growth: | pH, temperature, oxygen concentration, moisture, hydrostatic pressure, osmotic pressure, radiation. |
| Nutritional Factors which effect bacterial growth: | availability of carbon, nitrogen, sulfur, phosphorus, trace elements and some vitamins. |
| Who invented the pH scale and why was it first used? | Danish chemist Soren Sorenson, to describe the limits of growth of microorganisms in various media. |
| Optimum pH | The pH at which microorganisms grow best |
| Acidophiles | "acid-loving" organisms, grow best at a pH of 1.0-5.4 |
| Neutrophiles | grow best at a pH of 5.4-8.0 |
| Alkaliphiles | grow best at a pH of 7.0-11.5 |
| The most common bacteria to cause disease in humans is classified as ________________ | Neutrophiles |
| "Buffers" are incorporated into laboratory culture media for what reason? | To help maintain proper pH levels (phosphate salts are a common example) |
| Obligate | Organism MUST have the specified environmental condition. |
| Facultative | Organism is able to ADJUST and tolerate more than one environmental conditions. |
| Psychrophiles | cold-loving organisms. grow optimally in temperatures of 15 to 20 degrees Celsius. |
| Mesophiles | (*Most Bacteria) grow best at temperatures between 25 and 40 degrees Celsius. |
| Thermophiles | heat-loving organisms. grow optimally at temperatures between 50 and 60 degrees Celsius. |
| Many thermophiles can be found where? | In compost heaps and a few (which can tolerate incredibly hot temperatures) in boiling springs. |
| The temperature range at which an organism grows is directly related to the temperatures at which its __________ function. | Enzymes |
| The "minimum growth temperature:" | the lowest temperature at which cells can divide |
| The "maximum growth temperature:" | the highest temperature at which cells can divide |
| The "optimum growth temperature:" | The temperature at which cells divide most rapidly (the strongest generation time) |
| The optimum temperature is typically very (near or far) to/from the maximum temperature. | Near |
| aerobes | require oxygen to grow |
| anaerobes | do not require oxygen to grow |
| capnophiles | Carbon dioxide loving organisms. |
| what substance can kill obligate anaerobes? | superoxide |
| How is super oxide created? | It is formed by oxidative enzymes and converted to molecular oxygen and toxic hydrogen peroxide by an enzyme called superoxide dismutase. |
| Hydrogen peroxide is converted to water and molecular oxygen by what enzyme? | Catalase |
| All actively metabolizing cells generally require what kind of environment? | PlasmolysisWater |
| How long can most vegetative cells survive without moister? | Hours |
| Which organism can survive in a dry environment (no moisture)? | Spores or spore-forming organisms |
| Hydrostatic pressure | pressure exerted by standing water in proportion to its depth. |
| Hydrostatic pressure doubles with every ____m increase in depth. | 10 |
| Barophiles | Live at high pressures |
| plasmolysis | shrinkage of the cell |
| Halophiles | Require large amounts of salt to survive |
| The unit of measurement for absorbed doses of radiation | Gray (Gy) |
| Fastidious | Require special nutritional needs that are difficult to obtain in the laboratory |
| Most bacteria use some _____-containing compound as an energy source. | carbon |
| All organisms need ___________ to synthesize enzymes, proteins, and nucleic acids. | What Nitrogen |
| Microorganisms use phosphorus to synthesize what? | ATP, phospholipids, and nucleic acids |
| How do microorganisms obtain sulfur? | From sulfur salts and sulfur containing amino acids. |
| What are "Trace Elements"? | Tiny traces of copper, iron, zinc, and cobalt. |
| Why do microorganisms require trace elements? | serve as cofactors in enzymatic reactions. |
| Human pathogenic organisms commonly require what substance from their host to survive? | Vitamins |
| nutritional complexity | the number of nutrients an organism requires to grow |
| nutritional complexity reflects a deficiency in __________ enzymes. | biosynthetic |
| Extra-cellular enzymes usually are produced by what? | Gram-positive rods |
| periplasmic enzymes usually are produced by what? | Gram-negative organisms |
| Three ways microorganisms adapt to limited nutrients; | 1. Synthesize increased amounts of enzymes 2. The ability to synthesize enzymes needed to use a different nutrient. 3. Adjusting the rate at which they metabolize nutrients (metabolism and growth slowed down) |
| The enzyme used to break down large carbohydrate molecules into smaller ones: | carbohydrase |
| the enzyme used to break down starch to maltose: | amylase |
| the enzyme used to break down cellulose to cellobiose: | Cellulase |
| The enzyme that breaks down sucrose to glucose and fructose: | sucrase |
| the enzyme that breaks down lactose to glucose and galactose: | Lactase |
| the enzyme that breaks down maltose to two glucose molecules: | Maltase |
| The enzyme that breaks down fats to glycerol and fatty acids: | Lipase |
| The enzyme that breaks down proteins to peptide and amino acids: | Protase |
| The enzyme that breaks down milk protein to amino acids and peptides: | Caseinase |
| The enzyme that breaks down gelatin to amino acids and peptides: | Gelatinase |
| What is quorum sensing? | used by bacteria to regulate gene expression in a cell-density-dependent manner. |
| Bioflims are a result of ___________________ | Quorum Sensing |
| Sporulation | formation of endospores |
| fungal spores are produced in great number and are a form of ___________ | reproduction |
| Can endospores divide? | No |
| How many daughter cells can parent endospore cells produce? | only one |
| The ______ is the living part of the endospore, made up of DNA and RNA. | Core |
| The core of an endospore contains ______ acid and _____ ions. | Dipicolinic acid, and calcium ions |
| An endospore spectum lacks what? | cell wall |
| What grows around the core? | endospore spectum |
| Some endospores have a lipid-protein membrane surrounding the mother cell, called ____________ | exosporium |
| During germination the endospore does what? | returns to its vegetative state, occurring in three stages (1. activation 2. germination proper 3. outgrowth) |
| conida | chains of aerial spores with thick outer walls |
| The proper way to perform pure cultures today: | streak plate method |
| The pour plate method makes use of serial ___________ | dilutions |
| the pour plate method is particularly useful for what type of bacteria? | microaerophiles that cannot tolerate exposure to O2. |
| synthetic medium | one which is created in the laboratory |
| selective medium | encourages the growth of some organisms and discourages the growth of others |
| differential medium | contains a constituent that causes a noticeable change. |
| unlike a selective medium, an enrichment medium does not do what? | discourage growth of other organisms |
| what technique is used to minimize the contamination of cultures? | aseptic technique |
| preserved culture | a culture in which organisms are maintained in a dormant state |
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