EXAM 2 Flashcards
Phototrophs
ENERGY acquires energy from sunlight
Chemotrophs
ENERGY organic/inorganic molecules break bonds in molecules to extract energy from electrons to turn energy into ATP
Autotrophs
CARBON self feeders - get carbon from Calvin Benson cycle
Heterotrophs
CARBON different feeders - take organic molecules get carbon from other organisms - glucose - proteins - fats
Obligate (strict) Aerobi
requires the presence of oxygen for growth
Obligate (strict) Anaerobic
cannot grow in the presence of oxygen - oxygen is toxic to them
Facultative Anaerobic
grow in the presence or absence of oxygen, but prefer to use oxygen
Microaerophilic
requires oxygen, but at lower than atmospheric concentrations (2-10%); concentration greater than 10% is toxic
Aerotolerant Anaerobes
Can grow with or without oxygen
Why is oxygen deadly to some microbes yet required for others?
Toxic forms of oxygen initiate chains of oxidation reactions that cause irreparable damage to a cell’s proteins and lipids.
Toxic forms of oxygen are a by-rpoduct of aerobic respiration.
Toxic forms of oxygen are excellent oxidizing agents
Singlet oxygen (1O2)
Molecular oxygen with electrons boosted to a higher energy state
Generated during aerobic metabolism
Generated during Photosynthesis; excess energy of electrons removed by
carotenoid pigments
Molecular oxygen with electrons at a higher potential
Superoxide radicals (O2-)
Formed in part during the incomplete reduction of oxygen in aerobic and
anaerobic respiration
Posses extra electrons
Interacts with other molecules (lipids, proteins, nucleic acid) is destructive
Highly reactive!
Peroxide anion (O22-) & (H2O2)
Formed during the breakdown of lipids and in reactions catalyzed by SOD
Also highly reactive!
Hydroxyl radical (OH)
Results from ionizing radiation and incomplete reduction of hydrogen peroxide
Most reactive form! But . . . typically not a threat to aerobes due to action of
catalase and peroxidase
Psychrophile
-5 to 20 degrees C
