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
A 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
