Chapter 1: metabolism Flashcards
Autotrophs are organisms that require what?
that require only very simple molecules as building blocks: CO2, NH3, H2O
How do photoautrophs get their energy?
Obtain energy in form of light which is use to drive the transfer of electrons from inorganic donors to CO2, resulting in the production of carbohydrates (CH2O)n
In some cyanobacteria and all plants, the inorganic donor is what?
the inorganic donor is H2O which is oxidzed to O2.
In certain cyanobacteria but not in plants, the inorganic donor is what?
Nitrogen which is oxidized to organic nitrogen compounds (via nitrogen fixation)
Purple and green photosynthetic bacteria employ what as electron donor?
sulfur compounds (H2S) as electron donor which is converted to elemental sulfur.
Chemoithotrophs obtain energy how?
From the direct oxidation of inorganic compounds such as NH3, H2S or even Fe2+
Are all chemolithotrophs autotrophs? If so give an example?
No they can convert CO2 to carbohydrates (without light).
What organism has the simplest nutritional requirements of all organisms?
Cyanobacteria that undergo nitrogen fixation; convert N2 from atmosphere into organic nitrogen compounds.
Why do purple and green photosynthetic bacteria use Sulfur compounds (H2S) as electron donor?
occupy such oxygen-free habitats as shallow muddy ponds in which H2S is generated by rotting organic matter.
What are heterotrophs?
obtain energy through oxidation of organic compounds and hence are ultimately dependent on autotrophs for these substances.
Obligate aerobes (including animals)
heterotroph that must utilize O2 to carry out its oxidation…thus cannot live without air
anaerobes
heteroptroph that employ oxidating agent such as sulfate or nitrate.
Sulfate-reducing bacteria do what?
carry out oxidation of sulfate
Denitrifying bacteria do what?
carry out oxidation of nitrogen
Many organisms undergo Fermentation. What does this mean?
when organisms can partially metabolize various organic compounds in intramolecular oxidation-reduction processes.
