Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
34 Cards in this Set
- Front
- Back
|
Growth
|
refers to increases in population mass (number of cells) rather than size of
individual organisms |
|
|
binary fission
|
Cells splitting in half.
|
|
|
Psychrophiles
|
– cold loving; grow in cold water and soil; none in human body
– -5°C and 15°C – Found in Arctic and Antarctic – Chlamydomonas nivalis – Obligate psycrophile – Bacillus globisporus (cannot grow above 20°C) – Facultative psycrophile – Xanthomonas pharmicola grows best below 20°C, but can also grow above 20°C |
|
|
Psychrotrophs
|
0°C– 35°C; spoilage
microorganisms – Can grow in refrigerated food and cause food-borne illness |
|
|
Mesophiles
|
– 25°C – 45°C
– Optimum ~37°C – E. coli – Most disease causing and spoilage bacteria |
|
|
Thermophiles
|
heat
loving – 45°C - 70°C – Lactobacillus delbrucckii bulgaricus (yogurt) |
|
|
Hyperthermophiles
|
(Extreme)
– 70 °C - 110 °C – Archaea – hot springs, hydrothermal vents |
|
|
pH
|
• Measure of acidity and alkalinity
• Despite pH of external environment, most cells maintain a constant pH near neutral pH (~7.0) |
|
|
Neutrophiles
|
most bacteria (pH 5 – 8)
|
|
|
Acidophiles
|
grow optimally pH<5.5
– Live in dry, acid soils (around volcanoes) – Thiobacillus ferroxidans |
|
|
Alkalinophiles
|
grow optimally pH > 8.5
– Live in alkaline lakes and soils |
|
|
Osmotolerant
|
can grow in relatively high sugar
solution |
|
|
Extreme Halophile
|
Requires very high NaCl, some
require >20% |
|
|
Obligate Halophile
|
require high salt
|
|
|
Facultative Halophile
|
do not require high salt, but can
tolerate salt up to ~2% – S.aureus on human skin |
|
|
Xerophiles
|
dryness – fungi
|
|
|
Barophiles
|
Hydrostatic pressure
– Pressure exerted by water • Exist under extreme pressure • Deep sea microbes |
|
|
Obligate aerobes
|
absolute requirement for
oxygen; generate energy in aerobic respiration (Pseudomonas); Have catalase and superoxide dismutase |
|
|
Obligate anaerobes
|
cannot multiply if any
oxygen is present, often killed by traces of oxygen; must use anaerobic respiration and/or fermentation for energy; Do not have catalase or superoxide dismutase (Clostridium botulinum) |
|
|
Facultative anaerobes
|
grow better if oxygen is present, but can also grow without it. (facultative means organisms is flexible). Use
aerobic respiration if oxygen is present, but use fermentation or anaerobic respiration if it is not. (E. coli); Have catalase and superoxide dismutase |
|
|
Microaerophiles
|
Require small amounts of
oxygen (2% - 10%) for aerobic respiration. Have small amounts of catalase and superoxide dismutase; Helicobacter pylori |
|
|
Aerotolerant anaerobes
|
are indifferent to oxygen. Can grow in presence of oxygen but do not use it to transform energy (do not use aerobic
metabolism) – Obligate fermenters – Lactobacillus bulgaricus, Streptococcus pyogenes |
|
|
Nutritional Factors that
Influence Microbial Growth |
• Growth also depends on available source
of chemicals to use as nutrients • Required elements • Carbon – source of carbon distinguishes different groups or prokaryotes – Heterotrophs - use organic carbon – Autotrophs – use inorganic carbon |
|
|
Required Elements
|
Carbon – component of amino acids, lipids,nucleic acids and sugars
• Hydrogen – component of all cellular constituents • Nitrogen – often rate limiting growth factor; component of all amino acids and nucleic acids • Sulfur – component of some amino acids • Phosphorus – component of nucleic acids, membrane lipids, and ATP |
|
|
Photoautotrophs
– Energy source: – Carbon source: |
– Energy source: sunlight
– Carbon source: CO2 |
|
|
Chemoautotrophs
– Energy source: – Carbon source: |
– Energy source: inorganic compounds (H2S, NH3, etc.)
– Carbon source: CO2 |
|
|
Photoheterotrophs
– Energy source: – Carbon source: |
– Energy source: sunlight
– Carbon source: organic compounds |
|
|
Chemoheterotrophs
– Energy source: – Carbon source: |
– Energy source: organic compounds (sugars, amino acids, etc.)
– Carbon source: organic compounds |
|
|
Four basic phases of
growth |
Lag phase – number of cells not increasing; bacteria synthesizing macromolecules
needed for growth Log phase – cells divide at constant rate (exponential growth) Stationary phase – bacteria stop growing after they have used up required nutrient(s) or oxygen; metabolites accumulate (cell death = cell growth) Death phase – number of viable cells decrease at a constant (exponential rate) |
|
|
Psychrophiles are organisms that grow
|
between 0 and 15 degrees Celsius
|
|
|
Most human pathogens are
|
Mesophiles
|
|
|
Minimum growth temperature is
|
the lowest temperature at which an organism will grow
|
|
|
Optimal growth temperature is
|
The temperature at which the highest rate of growth occurs
|
|
|
Acidophilic bacteria grow best at
|
ph 2
|
