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22 Cards in this Set

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Regulation metabolic pathways
Regulation is required because..
of the shifting demands in the human due to different physiological situations.
Regulation metabolic pathways:
the shift in demand for energy (ATP) can increase > 100-fold due to?
exercise.
Regulation metabolic pathways
Changes in diet (eg., starvation) would cause
shifting from?
one pathway to another.
Regulation of metabolic pathways:
Regulation is required because the shifting demands due to different physiological situations
How is this done? i.e., what mechanism do cells utilize to maintain homeostasis?
It is important to know that despite variances in diet in quantity and quality living cells maintain a dynamic steady state.
Regulation of metabolic pathways
the substrate in each metabolic pathway is provided by ...?
the preceding reaction at the same rate it is consumed.
Regulation of metabolic pathways

The flux in the pathways during regulation may be at any rate but the concentration of S ...

Thus,
v1 v2
A -------> S ----------> P and v1 = v2 therefore S =?
- does not change.

- constant.
Regulation of metabolic pathways
If the steady state is changed then altered fluxes cause ....
regulatory mechanisms to become operative.
Regulation of metabolic pathways
An important function of the cell is to maintain a ......... since any change in ATP supply would effect many pathways.
constant [ATP] concentration
Regulation of metabolic pathways
a ____________ mechanism has been developed to maintain the ATP concentration.
regulatory
Regulation of metabolic pathways

When ATP is utilized it is converted to ?
ADP or AMP
Regulation of metabolic pathways

ADP is in equilibrium with .... via the Adenylate kinase reaction.
AMP and ATP
Regulation of metabolic pathways
ADP is in equilibrium with AMP and ATP via ?
the Adenylate kinase reaction
Regulation of metabolic pathways
2 ADP <=====> ????????
ATP + AMP
Regulation of metabolic pathways
some regulatory reactions are affected by the ???? ratio.
[ATP]/[AMP]
Regulation of metabolic pathways
It turns out that AMP is .............. of the energy state of the cell.
a more sensitive indicator
Regulation of metabolic pathways
It turns out that AMP is a more sensitive indicator of the energy state of the cell. This is due to..
the fact that ATP is high (~5 to 10 mM) compared to AMP (~0.1 mM).
Regulation of metabolic pathways
If 10% of the ATP is used in a reaction there are bigger changes in the AMP concentration due to...
the adenylate kinase reaction.
Regulation of metabolic pathways
a 10% decrease in ATP there is a .........in AMP.
6-fold or 600% increase
Regulation of metabolic pathways
the cell many regulatory processes are affected by ???
[AMP].
Regulation of metabolic pathways
4 Regulatory processes that are present in the cell
1. Maximize fuel utilization efficiency by preventing simultaneous operation of pathways in opposite directions. (eg., gluconeogenesis and glycolysis).
2. Partition of metabolites between alternative pathways such as glycolysis and pentose-P pathway.
3. Utilizing the fuel best suited for the needs of the organism.
4. Regulation of biosynthetic pathways when their end products accumulate.
Regulation of metabolic pathways
Usually the regulatory enzyme is never at its equilibrium as it is a rate limiting reaction compared to other enzymes in the cell. Because of the prevailing concentrations of
substrates and effector molecules. Regulatory enzymes are thus,
exergonic.
Regulation of metabolic pathways

Steps 2 and 3 in regulatory pathways are ...... while step 1 is ....... in steady state
- at equilibrium

-not when the pathway is