Exam 2: growth Flashcards
Growth
An increase in size, population, or development of an organism
Nitrogen Fixation
The chemical processes by which atmospheric nitrogen is assimilated into organic compounds
Biofilm
A dynamic, heterogeneous, community of microorganisms adhered to an artificial surface
Defined media
A nutrient media in which all the chemical compounds are known
Complex media
An uncharacterized nutrient media with undefined ratios of essential elements
Selective media
A nutrient media that inhibits the growth of particular types of organisms
Differential media
A nutrient media that allows for the identification of particular types of organisms
Lyophilize
To freeze dry
Binary fission
A type of asexual reproduction utilized by prokaryotes that results in subdivision of a single organism into two or more separate organisms
Generation Time
Time required for a bacterial cell to grow and divide
Understand how organisms are divided into nutritional categories based on carbon and energy source
Two groups of organisms based on source of carbon
Autotrophs - utilize CO2
Heterotrophs - catabolize organic compounds
Two groups of organisms based on source of energy
Chemotrophs - use organic compounds
Phototrophs - acquire energy from light
Mixtures:
Photoautotrophs: use CO2 as a carbon source and acquire energy from environmental light (plants)
Chemoautotrophs: use CO2 as a carbon source & catabolize organic molecules for energy
Photoheterotrophs: Photosynthetic organisms that acquire energy from light and acquire nutrients from catabolism of organic compounds
Chemoheterotrophs: use organic compounds for both energy and carbon
Compare the oxygen requirements of aerobes, anaerobes, facultative anaerobes, aerotolerant anaerobes and microaerophiles
Aerobes: oxygen is essential
Anaerobes: oxygen is deadly
Facultative anaerobes: metabolic efficiency reduced in the absence of oxygen. Can undergo aerobic & anaerobic respiration
Aerotolerant anaerobes: do not use aerobic metabolism, but tolerate oxygen by having some enzymes that detoxify poisonous oxygen forms
Microaerophiles: require oxygen levels of 2% –10%
–Can compare all of these when looking at an FTM, fluid thioglycollate medium (gets rid of all oxygen)
Discuss the elements required for growth and how they are utilized
Most common nutrients contain CHNOPS
1. Trace elements - only required in small amounts
2. Growth factors - necessary organic chemicals that cannot be synthesized by certain organisms
3. Nitrogen requirements
Often growth limiting - anabolism often ceases due to insufficient nitrogen
All cells recycle nitrogen from AAs and nucleotides
Discuss how physical parameters, such as temperature, pH, osmolarity and pressure affect microbial growth
Temperature: Denaturation through disruption of H bonds in proteins (loss of function)
- Low temp: membranes rigid & fragile, no kinks
- High temp: membranes fluid, kinks present
Categories of microbes based on temperature
Psychrophiles (~-5-20 degrees C)
Mesophiles (~15-45 degrees C) (important bc we’re 98F)
Thermophiles (~45-80 degrees C)
Hyperthermophiles (~65-105 degrees C)
pH: Organisms sensitive to acidity changes; H+ and OH- interfere with H bonding
- talk ab acidophiles, neutrophiles and alkaliphiles
Osmolarity: Most cells die in absence of water; Microbes require water to dissolve enzymes & nutrients
Pressure:
Osmotic pressure
- Pressure exerted on a semipermeable membrane by a solution containing solutes that cannot freely cross membrane
Hydrostatic pressure
- Water exerts pressure in proportion to its depth
- Barophiles depend on pressure to maintain their 3D functional shape
Explain the importance of aseptic and pure culture technique. Provide examples
Prevents contamination of sterile objects
- Washing of hands
- PPE such as gloves and masks
Necessary for isolation of a specific microorganism, especially in the diagnosis of disease. Pure culture technique allows us to isolate one species & know that it’s colony came from one and only one progenitor → CFU
2 common isolation techniques:
Streak plates
Pour plates
