Lec 19: Case Study - Microbes on a changing planet Flashcards
what are the to subcycles of the carbon cycle?
- rapid (biological) carbon cycle –> LIVING organisms
- long-term (geological) carbon cycle –> plate tectonics
what is the role of microbes in the global carbon cycle?
microbes are hetetrophic. when they respire and decompose they release CO2.
what is organic matter?
material coming from a recently living organism (dead plants and animals, their waste)
Where is most organic matter derived from on earth?
plants
Where is most organic matter derived from in the ocean?
phytoplankton (which are bacteria or eukaryotes)
what is one of the major constituents of organic matter?
carbon
what percentage of Earth’s organic carbon is stored in organic matter?
40%
What is bioavailability of organic matter?
how much of the organic matter that microbes can eat
what do we call organic matter that is most bioavailable?
labile
what do we call organic matter that is least bioavailable?
recalcitrant
which factors determine the bioavailability of a compound?
- size: smaller = easier to eat
- chemical structure (more rings = less edible)
what are the three pools that make up organic matter
active, slow, and stable
how many isotopes does carbon have? which one is radioactive?
- C14 is radioactive
which carbon signatures can you measure?
C13 and C14 signatures (least abundant isotopes)
what do we use C13 values for?
do determine the source of carbon (land or water)
What do we use C14 values for?
to date material
What does the “you are what you ear principle” allow us to do
determine what an organism was eating or breathing
how do microbes break down big pieces of organic matter?
with extracellular enzymes
according to Nagissa’s study, what does organic matter degradation also depend on?
the types of microbes that are present and activee
what will happen as permafrost warms?
microbes become active, eat organic matter, and release CO2
what kinds of microbes are likely to become active after the thawing of the permafrost?
methanogens (prokaryotes)
What are we still unsure about regarding the thawing of permafrost?
- don’t know how labile the organic matter in permafrost is
- don’t know how quickly microbes would degrade this organic matter
- don’t know WHICH microbes will become more active (methanogens?)
Why are changes in microbial activity important?
they form the base of the food chain, therefore a change in their activity will affect the entire ecosystem
