18 Flashcards
Tritophic interactions?
Interactions between plant herbivore interactions.
Structure of tannins?
Phenyl ring with acidic hydroxyl or phenolic group. They become Gallic acid which can polymerize to become gallotannin.
Tannins are in?
All kinds of food
Why do plants have tannins?
Protecting plants from mammalian herbivores
Astringency?
Tannins form bonds with salivary protein leading to protein precipitation.
How does Astringency work?
The charge in carboxyl group of amino acids can interact with the dipole charges of the tannin. It creates this week tannin-protein interactions via hydrogen bonds.
Tannins are thus a general defense against herbivores because?
They interfere with protein digestion.
What kinds of information is needed to test the defense against herbivores interfering with protein digestion?
Artificially added tannin to leaves and measure caterpillars performance via bioassasy. They measured their mortality rate, relative growth rate.
Tannins is inducing what kind of herbivores defense in insects?
Increase mortality rate, nothing else.
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Chemical context dependence: pH to explain why do tannins interfere with protein digestion in moose but not in caterpillars?
Tannins are acidic and enters an acidic gut (pH 4-5) of a mammalian herbivore. It ionizes in base. The average caterpillar mid-gut is basic.
Pro-oxidants ?
A substance that causes production of damaging oxidative products: damage gut lining itself.
If tannins are primarily a defense against mammalian herbivores, why do they still increase the mortality rate in caterpillars?
Pro-oxidants.
!Mechanisms of tannin activity?
Depends on the number of gallonyl groups (decrease) in the molecule and protein precipitation capacity (increase).
Context dependence - the eternal triangle? 3•
[source: plant, chemical], [Receiver: insect, pathogen, mammal, metabolic function], [Environment: temperature, pH, UV, chemical, third organism]
