A colony, which is a visible population of microorganisms arising from a single cell or
colony-forming unit living in one place, grows in size as the
... [Show More] number of cells
increases. Most microbes live as biofilms, that is, in association with one another on
surfaces.
Microbial colony
Chemical nutrients such as carbon, hydrogen, oxygen, and nitrogen are required for
the growth of microbial populations. Obtain from environment, can cause disease as
they interfere with host metabolism.
Nutrients
1. Autotrophs=utilize and inorganic carbon source (CO2) as sole source of carbon--
"feed themselves."
2.Heterotrophs=catabolize reduced organic molecules they acquire from other
organisms to get carbon.
Organisms can be categorized into two big groups based on carbon source
1. Chemotrophs=acquire energy from redox reactions involving inorganic and
organic molecules
2. Phototrophs= use light as their energy source
Organisms categorized into two groups pbased on energy source
1. Photoautotrophs (plants, some protozoa, algae).
2. Chemoautotrophs
2. Photoheterotrophs
2. Chemoheterotrophs (animals, fungi, other protozoa).
Bacteria have members in all four groups.
Four basic groups of organisms based off carbon source and energy source
Another name for heterotrophs. Acquire electrons from same organic molecules that
provide them carbon.
Organotrophs
Another name for autotrophs. Acquire electrons from inorganic sources.
Lithotrophs
1. Obligate aerobes require oxygen molecules as the final electron acceptor of their
electron transport chains. (Algae, most fungi, most protozoa, many prokaryotes).
2. Obligate anaerobes cannot tolerate oxygen and must use an electron acceptor
other than oxygen. (Some protozoa, some prokaryotes).
Obligate aerobes and obligate anaerobes
Atmosphereic oxygen and oxygen derived from organic compounds like carbs aren't
poisonous. But otherwise, oxygen is good oxidizing agent and steal electrons from
other compounds which in turn steals electrons from other compounds--this chain
causes damage to cells [Show Less]