Regulation of Bacterial Growth Flashcards
Evidence of Regulatory Mechanisms
- Biochemical _____ of a substrate does not take place until the _________ supply of the substrate is _______
- When ______ substrates are available, the more rapidly _________ substrate (less ________ complex) is used first
- synthesis; exogenous; exhausted
- multiple; metabolized; structurally
Two Types of Regulatory Mechanisms
- Regulation of _________ pathways
- Regulation of _____ via ________ control
- metabolic
2. genes; transcriptional
Regulation of Metabolic Pathways: Feedback Inhibition
-Typical example is a ______ late in the pathway inhibiting an ______ earlier in the pathway
-metabolite; enzyme
Other Types of Feedback Inhibition
- ______ ______ _______: End products of different branches in the pathway can ______ _______ enzymes early in the pathway. Different _______ can be effected by different end products making this possible. End products reduce the _______ of the enzymes in different _______, do not completely _______ an enzyme
- ______ _____ ______: End products will _______ ______ the enzymes located at the beginning of the branch to more tightly regulate a branch product without _______ all the branch products. When ____ the branch-point enzymes are inhibited, the substrate they act on will ______ _______ an enzyme _______ in the pathway
- ____-______ _______: Intermediates early in the pathway can ______-_______ to inhibit enzymes at the branch-point
- _____-_____ ______: Intermediates early in the pathway can _____-______ to activate enzymes at the branch-point
- Cumulative Feedback Inhibition; feedback inhibit; isozymes; activity; ratio; inactivate
- Sequential Feedback Inhibition; feedback inhibit; inhibiting; ALL; feedback inhibit; earlier
- Feed-forward Inhibition; feed-forward
- Feed-forward Activation; feed-forward
Allosteric Enzymes
-____ _____: Additional binding site separate from the active site that can bind an ______ or ______, when these bind they change the _____ of the active site. ______ prevent the binding of a ______ to the active site
Enzyme Kinetics:
-Allosteric enzymes demonstrate a ______ curve due to _________
-Regular enzymes demonstrate ______-_______ Kinetics showing a ______ curve
- Allosteric Site; activator; inhibitor; shape; Inhibitors; substrate
- sigmoidal; cooperativity
- Michaelis-Menten; hyperbolic
Feed-forward Control in Streptococcus mutans
Key Enzymes:
1. _____ Kinase: Converts PEP to Pyruvate
2. ________ Dehydrogenase: Converts Pyruvate to _________
3. ________ _____ ______: Will produce other acid products like ______, _____, and ______
Limited Sugar:
-_______ _________: Majority of the end products are mixed acids
Excess Sugar:
-_________ _______: Majority of the end products is lactic acid, which is much stronger with a lower ____ which is why _____ sugar is more _______
Feed-forward Activation of:
-_______ ________ by G6P
-_______ _________ by Fructose 1,6-diphosphate
Feed-forward Inactivation of:
-______ _______ ______ by Triose 3-phosphate
- Pyruvate
- Lactate; lactate
- Pyruvate Formate Lyase; formate; acetate; ethanol
- Heterolactic Fermentation
- Homolactic Fermentation; pKa; excess; Cariogenic
- Pyruvate Kinase
- Lactate Dehydrogenase
- Pyruvate Formate Lyase
Smart Sugars: Non-fermentable Sucrose Derivatives
- Linkage _____ that are twisted versions of Sucrose
- _______ ______ can NOT ferment smart sugars, however another oral bacteria ________ _______ can ferment _______ (everything but ________)
- isomers
- Streptococcus mutans; Leptotrichia buccalis; 4/5; Leucrose
Regulation of Gene Expression: Transcriptional Control
- ______: Control of a single specific operon. Example is the _____ operon, a cluster of _______ and _____ genes that participate in ______ transport and metabolism. ______ and ________ genes.
- ______: Control of multiple operons at once. Example is ______ repression, the ability of a rapidly metabolized substrate to ______ the synthesis of specific gene products. How bacteria can control growth when presented with _______ substrates
- Local; lac; structural; regulatory; lactose; Constitutive; inducible
- Global; Catabolite; suppress; multiple
Local Control of Lactose Metabolic Pathway
3 genes:
1. _____: Gene that encodes for the _________ _______: Responsible for transporting lactose into the bacteria. Example of a ______ symport and NOT the ___ System
2. _____: Gene that encodes for -________: Cleaves lactose into glucose and galactose, both ultimately converted into _______--______
3. ______: Gene that encodes for the __-_______ ________: Enzyme involved in the conversion of galactose to G6P
-Drs. ______ Jacob and _____ Monod found cells can turn ____ and _____ certain genetic information. Seminal discovery in bacteria of how ____ are regulated and were awarded the ______ Nobel Prize for Physiology or Medicine
- lacY; Galactosidase Permease; proton; PTS
- lacZ; β-Galactosidase; Glucose 6-Phosphate
- lacA; β-Galactosidase Transacetylase
- Francois; Jacques; on; off; genes; 1965
Lac Operon: Negative Control
-____: Gene that encodes for the repressor protein
Growing Without Lactose
-Can be lactose or a compound _______ similar
-_______ protein is continuously synthesized and ____
-________ protein binds to the ______ region preventing ______ of the 3 structural genes
Growing With Lactose
-Lactose or _______ similar analogs will act as ________, they are transported into the cell and ______ the repressor by _______ to it allowing for the ________ of the operon
-______ ______ _______: Presence of the substrate will inactivate the ______ repressor protein allowing for transcription and translation
- Structural genes will still be _________ even at low [lactose]
- lacI
- structurally
- Repressor, active
- Repressor; operator; expression
- structurally; inducers; inactivate; binding; expression
- Inducible Negative Control; active
- expressed
Arabinose Operon: Positive Control
-Similar in composition to the ____ operon
Growing Without Arabinose
-Arabinose or _______ analogs are not present
-_______ will prevent expression of the structural genes
Growing With Arabinose
-Arabinose or _______ analogs are present
-_______ to the repressor does NOT ________ it, but leads it to bind to a region_______ from the operator. This ______ transcription
- lac
- structural
- Repressor
- structural
- Binding; inactivate; downstream; activates
Glob al Control of Multiple Metabolic Pathways
Standard Bacterial Growth Curve:
1. _____ ______: Inoculated cells that are adapting to the new environment and there is no _______ in the number of cells
2. ___/______ _____: Cells are dividing at a maximum rate resulting in _____ increase in growth
3. _______ _______: Nutrients have been depleted and/or the ___ of the medium has become too acidic due to _______ resulting in no increase in cell number
4. _____ _____: Cells slowly degrade and are lysed
- Lag Phase; increase
- Log/Exponential Phase; exponential
- Stationary Phase; pH; fermentation
- Death Phase
Global Control of Multiple Metabolic Pathways
Growth on 2 Substrates:
-[______] will decrease rapidly since it’s a monosaccharide and is less ________ complex
-________ in bacterial cell growth corresponds to when _______ is being rapidly depleted
-Typically measure [__-_______] to measure bacteria growing on lactose, [__-______] synthesis increases ______ in assays as glucose is less ________
Bacteria ONLY Growing on Lactose
-______ ______: Measure in the increase in the bacterial number
-Rapid ________ increase in [__-________] represents a __________ increase of cell growth
-Addition of ______ will result in a ___ phase where new genes are activated to utilize the ______ over lactose
-Addition of both _____ and _____ will result in NO CHANGE in [__-_______] even with ______ being present. _____ prevents the switch from lactose to _______, indicating that _____ NOT ______ controls the switch
- [Glucose]; structurally
- Increase; glucose
- [β-Galactosidase]; [β-Galactosidase]; later; available
- Optical Density
- exponential; [β-Galactosidase]; exponential
- glucose; lag; glucose
- glucose; cAMP; [β-Galactosidase]; glucose; cAMP; glucose; cAMP; glucose
Global Regulatory Mechanism: Catabolite Repression
Bacteria Growing on Glucose:
-Typical _____ pathway
-______ _____ needs Enzyme III from the _____ System to fully function in ________ glucose
-______ ____ _____ ____(____): Activating protein that will drastically increase the rate of expression when bound to cAMP
- Low [___] due to high [glucose] resulting in a low rate of _________
Glucose is Depleted
-Enzyme III ______ and activates _____ _____ only when glucose is depleted, this increases [_____]
-High [____] will bind to CAP _____ it, CAP can bind to many operons to significantly ______ transcription of structural genes
-High [____] due to low [glucose] resulting in a high rate of ___________
- PTS
- Adenylate Cyclase; PTS; phosphorylating
- Catabolite Gene Activating Protein (CAP)
- [cAMP]; transcription
- phosphorylates; Adenylate Cyclase; [cAMP]
- [cAMP]; activating; enhancing
- [cAMP]; transcription
Summary of Bacterial Metabolism Regulation
- Turning pathways on or off via ______ enzymes
- Turning genes on or off via ________ control. ____ control of a ______ specific operon, or _____ control via _______ ______
- Allosteric
2. Transcriptional; Local; single; global; Catabolite Repression
