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23 Cards in this Set
- Front
- Back
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Substrate |
the reactant molecule on which an enzyme works |
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Enzyme-substrate complex |
the enzyme modified active complex |
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Substrate specificity |
the extent to which an enzyme is selective in catalyzing a reaction with a specific substrate |
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High Specificity vs. Low Specificity |
High Specificity: reacts with one or a few substrates Low Specificity: reacts with many substrates |
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Enzymes |
-nearly all proteins -depend on 3-d structure to function -contain transition metals at active site often -increase reaction rates many fold (ex. 10,000,000) |
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Competitive Inhibitors |
occupy the active site of the enzyme and block access to the normal substrate --can bind reversibly or irreversibly to the active site-- |
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Noncompetitive Inhibitors |
occupy an allosteric site and thereby change the shape of the active site so the substrate can no longer bind --important in feedback inhibition cycles-- |
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Feedback Inhibition |
a cell product acts as a noncompetitive inhibitor, to stop the cell from producing more than it needs |
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motility- how fast are bacteria |
50 micrometers/sec |
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how do bacteria move? |
runs (CCW) and tumbles (CW) |
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chemotaxis |
motion in response to a chemical stimulus |
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biased random walk |
cells tumble less in higher concentrations of whatever they are attracted to (or lower levels of what they want to avoid) which results in the bias random walk |
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Adaptation of cell chemotaxis |
the cell will reset the methylation circuit to tumble at a normal rate under new solution conditions |
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Quorum sensing |
a system of stimulus and response correlated with population density of the same organism in the surrounding area |
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Vibrio fischeri |
using quorum sensing, it determines when to turn on its light, because low levels of bacteria would be a waste of energy because it would not be bright enough to see |
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N-acyl homoserine lactone |
the signal used by vibrio fischeri |
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Acyl-homoserine lactones (AHL) |
the signal used in gram negative bacteria with different r-groups attached |
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Ogliopeptide Autoinducers |
the signal used in gram positive bacteria with different conformations |
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Interspecies sensing |
the signal released is universal so bacteria can sense how many of their own there are and how many others there are (S-THFM borate) |
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Death signals |
a certain type of signal can cause death in other types of bacteria through their quorum sensing |
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Quorum Quenching |
messing with the QS of other species |
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autoinducer inactivation |
destroys the signals, thus they organism doesn't receive them |
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autoinducer antagonist |
sends antagonistic signals |
