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118 Cards in this Set
- Front
- Back
Microbial Cell growth (picture) |
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Most prokaryotes duplicate themselves by _____/_____. |
Binary/fission |
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There are more than _____ chemical reactions that occur to duplicate a cell. |
2000 |
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What is the shortest known microbial doubling time? |
Shortest known microbial doubling time is 6 minutes |
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How long does it take microbes in sea sediments to double? |
Microbes in sea sediments may take decades to double |
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How long does it take E. Coli to double? |
E. Coli doubles about every 20 minutes |
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The general process of binary fission in a rod-shaped prokaryote. (picture) |
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Microbial growth is _____ - the number of cells double per unit time |
exponential |
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Define exponential growth |
the number of cells doubles per unit time |
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The number of cells in a bacterial culture is a function of what? |
the number of cells in a bacterial culture is a function of 2 (one parental cell gives rise to two daughter cells) |
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What is the number of cells in a bacterial culture a factor of two? |
One parental cell gives rise to two daughter cells |
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Population growth formula |
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In the population growth formula what does N, Nknot, and n stand for? |
N = final cell number, Nknot = initial cell number, n = number of generations |
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From the population growth formula what other equation can you derive? |
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Define Lag Phase |
Time before exponential growth starts. Cells adapt to the medium. Resynthesize essential components for growth. |
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Define exponential phase |
Time of exponential growth. Influenced by environmental conditions |
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Define Stationary phase |
Growth stops. Due to limiting nutrients or buildup of waste. Basic cellular functions continue |
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Define Death Phase |
Cells die off |
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Do bacteria get 'old'? |
YES! - the cell that inherits the "old pole" exhibits a diminished growth rate, decreased offspring production, and an increased incidence of death |
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"aging" of cells (picture) |
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Why do bacteria age? |
Asymmetric division of materials in the cell |
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Asymmetric division of materials in the cell (picture) |
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What are the four main environmental factors affecting microbial growth? |
1. Temperature 2. pH 3. Water availability 4. Oxygen |
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What are the 3 cardinal temperatures and define them |
Minimum temperature - below this temperature growth no longer occurs Optimum temperature - growth is most rapid Maximum temperature - above this temperature growth is not possible |
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The ______ temperature is always near the maximum temperature |
Optimum |
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Cardinal temperatures (picture) |
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The absolute values of the cardinal temperatures varies greatly between microorganisms (T/F) |
True |
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What is the typical growth range of most microorganisms? |
Typical growth range 30-40C |
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Much of the earth is hot. (T/F) |
False. Much of the earth is cold |
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What is the average temperature of oceans? |
oceans have average temperature of 5C |
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In polar regions there are large areas of land that are frozen much of the time (T/F) |
True |
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Define Psychrophiles |
Optimal growth temperature below 15C |
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What are two examples of psychrophiles? |
Snow algae - grows on the surface of snow in permanent snow fields Chemoorganotrophic bacteria found in polar ice |
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Where are they searching for life (a very cold place on Earth)? |
Search for life in Lake Vostok |
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Define Psychrotolerant |
Can grow at low temperatures, but optimum temperature is between 20-40C |
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Psychrotolerant microbes are less common than psychrophilic organisms. (T/F) |
False. More common than psychrophilic organisms |
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Where might psychrotolerant microbes live? |
Soil and water in temperate climates |
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On what might psychrotolerant microbes live on? |
Found on refrigerated food - meat, dairy, cider, vegetables, fruit, etc. |
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What type of microbes can be psychrotolerant? |
bacteria, fungi, algae, and protozoa |
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What are the characteristics of enzymes that function best at cold temperatures? |
Have more alpha-helices and less beta-sheets Have more polar and less hydrophobic amino acids |
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What molecular adaptations to membrane lipids do cold living microbes have? |
Membrane lipids contain more unsaturated fatty acids. |
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What does a membrane lipid containing more unsaturated fatty acids do? |
Will allow it be more fluid at low temperatures |
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What do cold living organisms do about freezing and requirement for liquid water? |
Take advantage of pockets of liquid water even below OC |
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What did they find from the Vostok ice core? |
A bacterial ice-binding protein from the Vostok ice core |
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Define Thermophiles |
optimum growth temperature is above 45C |
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Where do Thermophiles live? |
Grow in hot springs where the water has cooled slightly |
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Define Hyperthermophiles |
optimum growth temperature is above 80C |
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Where do Hyperthermophiles grow? |
Grow in hot springs near boiling point of water Grow around deep sea hydrothermal vents about 100C |
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Hyperthermophiles include a large variety of ______ organisms - including both _____ and ______ |
prokaryotic Bacteria Archaea |
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What are the difference in proteins for thermophily? |
increased number of ionic bonds between amino acids Densely packed highly hydrophobic interiors Chemicals (e.g. diglycerol phosphate) produced to stabilize proteins |
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What are the differences in lipids for thermophily? |
Lipids rich in saturated fatty acids Hyperthermophilic Archaea have diglycerol tetraethers - form a monolayer |
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What are the differences in DNA for thermophily? |
Specialized DNA enzyme - reverse DNA gyrase - introduces positive supercoils into the DNA preventing denaturation |
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Define reverse DNA gyrase |
Introduces positive supercoils into the DNA preventing denaturation |
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What is an example of life without light? |
Hydrothermal vents |
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Archaeal membrane structure: lipid bilayer (picture) |
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Archaeal membrane structure: lipid monolayer |
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Where are hyperthermophiles on the tree of life? |
Hyperthermophiles cluster near the hypothetical root of the tree of life, in both Bacteria and Archaea |
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What was Dr. Karl Stetter trying to do? |
Looking for life in volcanoes |
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In 2003 what did Dr. Karl Stetter receive? |
in 2003, Stetter was honored with the Leeuwenhoek Medal by the Royal Netherlands Academy of Arts and Sciences |
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What is the significance of the Leeuwenhoek Medal? |
This award is given every 10 years to the scientist who has made the most outstanding contributions to the advancement of microbiology |
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All hyperthermophiles are near the root of the tree of life. (T/F) |
True |
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Define Acidophiles |
Grow best at low pH |
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Define Obligate acidophiles |
unable to grow at neutral pH |
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What is the main issue with acidophiles? |
Stability of the membrane is the main issue |
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What do acidophiles need in order to stabilize their membranes? |
Need high concentration of H+ ions for membrane stability |
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Define Alkaliphiles |
Grow best at high pH |
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Where do Alkaliphiles grow? |
Live in highly basic environments - soda lakes and high carbonate soils |
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What is the main issue for Alkaliphiles? |
Generation of the proton motive force is the main issue |
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What do some Alkaliphiles use for transport and motility? |
Some use Na+ gradient for transport and motility |
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Some Alkaliphiles still use PMF for ATP synthesis. (T/F) |
True |
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In both acidophiles and alkaliphiles the _____/_____ often remains near neutrality. |
Intracellular/pH |
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What does a neutral intracellular pH prevent? |
prevents the destruction of macromolecules |
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In both acidophiles and alkaliphiles the _____ is highly buffered. |
Cytoplasm |
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What are the extreme limits of intracellular pH? |
4.6-9.5 |
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Yellowstone is home to what microorganism? |
Sulfolobus acidocaldarius |
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Where does Spirulina live? |
Lake Magadi in Africa. A 'soda' lake. High in carbonates. Contains Spirulina |
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Define Halotolerant and Halophilic Microorganisms |
Organisms that can grow at high concentrations of salt |
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What happens to most microorganisms at high salt concentrations |
Most microorganisms dehydrate and die at high salt concentrations |
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Define Halotolerant |
microorganisms can tolerate high salt concentrations |
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When do Halotolerant organisms grow best? |
Grow best without added salt |
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Define Halophilic |
Microorganisms usually require Na+ for growth |
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Where are halophilic organisms usually found? |
Often found in the ocean - 3% NaCl |
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How does a cell bring in water? |
To bring in water a cell must increase the internal solute concentration |
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Cytoplasm usually have _____/_____/_____ - water _____ in. |
high/solute/concentration diffuses |
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In order to bring in water what does a cell need to generate? |
Need to generate a positive water balance. |
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What does a cell do to generate a positive water balance? |
Pump in ions from environment Concentrate organic solutes |
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Low "water activity" must not interfere with what? |
Must not interfere with biochemical processes |
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What are compatible solutes? (list them) |
sugars, sugar alcohols, alcohols, amino acids and their derivatives, K+ ions |
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What color are the San Fransico Bay area salt ponds? |
Red |
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What lives in the San Francisco Bay area salt ponds? |
Halobacteria |
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What is the story of Owens Lake, CA? |
Owens Lake was once a vast blue lake, before it was drained (by diverting Owens River) to provide the city of Los Angeles with water. Today it is a pinkish-red, dry lake bed (playa) teaming with salt-loving Archaea |
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How is water activity related to the food industry? |
Traditional methods to control microbial spoilage, such as salting, smoking, and drying, are based on reducing the water activity of the meat Can also apply bacteriostatic substances such as formaldehyde and phenolic compounds in smoke |
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Halophiles cannot grow on salted food. (T/F) |
False. Halophiles can still grow on salted food! |
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What is Shark bay, Australia full of? |
The bay is full of stromatolites, rocky formations up to 1.5 metres high which were built by colonies of halophilic cyanobacteria (the first ever oxygen photosynthesizers) |
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Define stromatolites |
rocky formations up to 1.5 metres high which were build by colonies of halophilic cyanobacteria |
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Cyanobacteria are halophilic but were not the first ever oxygenic photosynthesizers. (T/F) |
False. Cyanobacteria is halophilic an they were the first ever oxygenic photosynthesizers |
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Oxygen is lacking in many microbial habitats. (T/F) |
True |
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O2 is poorly _____ in water. |
Soluble |
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What happens to 02 that dissolves quickly in water? |
O2 that does dissolve is quickly used up by organisms |
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What are some examples of O2 poor environments? |
Muds and sediments, marshes and bogs, waterlogged soils, intestinal tract of animals, sewage sludge, areas deep below the earth's surface |
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define obligate aerobes |
must grow at full O2 tensions - 21% |
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Define facultative aerobes |
can grow either with or without O2 |
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Define Microaerophiles |
Require reduced O2 tensions |
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Define aerotolerant anaerobes |
tolerate O2 but do not use it |
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Define Obligate Anaerobes |
Cannot grow in the presence of O2 |
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Oxygen classes (diagram) |
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What do Obligate aerobes require? |
Obligate aerobes require aeration Require shaking or bubbling air through medium |
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In an anaerobic culture what must be excluded? |
O2 |
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How can you make an anaerobic culture where O2 is excluded? |
Tubes can be filled to the top and tightly sealed Add reducing agent - thioglycolate (reacts with O2 in the medium) Anaerobe jar (anoxic jar) Gas pack replaces air in jar with H2 and CO2 Catalyst consumes O2 |
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Why are some microbes unable to grow in oxygen? |
Oxygen toxicity |
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Byproducts of oxygen are often highly _____. |
Toxic |
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Why are some of the byproducts of oxygen highly toxic? |
Spontaneously oxidize cellular marcomolecules produced by photooxidation and biochemically by peroxidase enzymes Organisms often contain carotenoids - detoxify the singlet oxygen into nontoxic forms |
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What are some of the toxic oxygen species produced as byproduct of reduction of O2 to H2O in respiration? |
Superoxide anion (O2-) Peroxides (H2O2) Hydroxyl radical (OH-) |
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What are the enzymes that destroy toxic oxygen? |
Catalase Peroxidase Superoxide dismutase Superoxide dismutase/catalase in combination |
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Oxygen toxicity can also occur in humans. (T/F) |
True |
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What happens if someone experiences oxygen toxicity? |
Again, excess oxygen can directly damage even human cells, e.g. Pulmonary oxygen toxicity |
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What species lives in Mono Lake, CA? |
Spirochaeta americana |
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Where are the four places we have been looking extra-terrestials, and why? |
Mars - now dry Enceladus - ice and water Titan - liquid methane Europa - sub-surface salty oceans |