Ruminants
Bobtail squid
Nitrogen-fixing bacteria
Biofilms
Miscellaneous
100
How many chambers are in a ruminant stomach?
4 Anaerobic environment
100
What bacteria colonize the bobtail squid?
Vibrio fischeri
100
What organisms can convert nitrogen gas into biologically useful nitrogen?
bacteria
100
biofilms are usually attached to a __________
surface
100
What is the term that describes a close association between two unlike organisms that is beneficial to one or both of them
symbiosis
200
What does VFA stand for?
Volatile Fatty Acids
200
the bacteria that colonize the squid use ________ _________ to control light production
Quorum sensing
200
what macromolecules contain nitrogen atoms?
proteins and nucleic acids
200
Microbes in biofilms are _______ times more resistant to microbiocides
1000
200
What type of images are generated by confocal microscopy?
3D images
300
What are VFAs used for?
Gives energy to the host
300
what term describes signaling molecules that are produced in response to changes in cell-population density?
autoinducer
300
what term describes the chemical processes by which atmospheric nitrogen is assimilated into organic compounds (ammonia)
nitrogen fixation
300
what are the advantages for bacteria growing in a biofilm?
1. the sharing of nutrients 2. shelter from harmful factors in the environment 3. the transfer of genetic information happens more easily in a biofilm
300
Free swimming (non-biofilm) bacteria are __________
Planktonic
400
Explain the association between hydrogen and methane gases produced in the rumen and climate change
Methane and hydrogen gases are released by ruminant animals into the atmosphere. Methane is a strong greenhouse gas.
400
Explain how the bacteria protect the squid
Light produced by the bacteria camouflages the squid from predators
400
Explain why we cannot use nitrogen atoms in the air to make our macromolecules?
atmospheric nitrogen does not easily react with other chemicals to form new compounds
400
describe the structure of a biofilm
microbes in a biofilm form pillar-like structures with water channels between them so water can carry incoming nutrients and outgoing waste. Individual microbes and clumps of slime occasionally leave the established biofilm and move to a new location where the biofilm becomes extended
400
The air we breathe is ____% nitrogen gas
78%
500
Describe how rumen animals breakdown cellulose into energy for the host.
microbes digest cellulose into sugars. Sugars are fermented into VFAs
500
Explain how the squid keeps a fresh culture of bacteria each night.
At sunrise, so many bacteria are in the squid's light organ that the squid cannot supply them all with nutrients, so it pumps most of them out. Through quorum sensing the bacteria can tell that most of their "friends" are gone and stop producing light. The pumping is tuned to the squid's circadian rhythm and it only activated at sunrise. As the day goes by, the bacteria divide, their numbers increase and more autoinducer accumulates. By nightfall, the light organ is on again.
500
Describe the symbiotic relationship legume plants have with nitrogen fixing bacteria
Bacteria form a nodule inside legumes. Then bacteria create ammonia from nitrogen in the air, which is used by the plant to create amino acids and nucleotides. The plant provides bacteria with sugars.
500
Explain how quorum sensing is necessary for biofilm formation
bacteria use quorum sensing to secrete an inducer. The inducer diffuses into the surrounding medium and bacterial cells move toward the source and begin producing an inducer. The concentration of inducer increases with cell number. This attracts more cells and initiates synthesis of more inducer
500
Describe generally how confocal microscopy works
Specimens are stained so they will emit light. But instead of illuminating the entire field, the light is shown through a really small pinhole and this is scanned across the sample and an image is built up.
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