Term
| What is a common way to regulate flux? |
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Definition
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Term
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Definition
| Flux is the rate of conversion of substrate to product. Also said, flux refers to the number of molecules that are processed in the pathway |
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Term
| What does feedback inhibition do to the rate limiting step in the pathway? |
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Definition
| Feedback inhibition is when excess product down regulates the activity of the first/rate-limiting step in the pathway |
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Term
| What is the purpose of segregating different pathways to separate organelles? |
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Definition
| It prevents common metabolic intermediates from one pathway acting on another pathway accidently |
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Term
| Why would you want to separate fatty acid synthesis and fatty acid oxidation into separate compartments within the cell? |
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Definition
| Fatty acids are broken down in the mitochondria to acetyl-CoA, while fatty acid synthesis occurs in the cytosol and requires acetyl-CoA. It would cause a paradox in the same compartment |
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Term
| Substrate inhibition leads to what regulatory event? What is the time required for this change? |
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Definition
| Leads to change in velocity, and happens immediately |
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Term
| Product inhibition leads to what regulatory event? What is the time required change? |
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Definition
| Change in Vm and/or Km. Happens immediately. |
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Term
| Allosteric control leads to what regulatory event? What is the time required change? |
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Definition
| Change in Vm and/or Km. Happens immediately |
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Term
| Covalent modification leads to what regulatory event? What is the time required change? |
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Definition
| Change in Vm and/or Km. Happens immediately or within minutes of change |
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Term
| Synthesis or degradation of enzyme leads to what regulatory event? What is the time required change? |
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Definition
| Change in the amount of enzyme. Happens in hours to days. |
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Term
| What will lead to the most dramatic shift in flux through pathways? |
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Definition
| Regulation of the speed of catalysis of the rate limiting step. |
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Term
| What is the functional group usually used for covalent modification of regulatory enzymes? |
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Definition
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Term
| How does phosphate modify a regulatory enzyme? |
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Definition
| The addition of a phosphate group changes the conformation of the enzyme and thus changes the enzymes activity |
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Term
| What enzyme will phosphorylate another enzyme/protein |
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Definition
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Term
| What enzyme will remove a phosphate group? |
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Definition
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Term
| Name two advantages of allosteric enzymes as regulatory enzymes |
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Definition
1. greater change in activity over smaller change in substrate (sigmoidal kinetics curve)
2. regulation is rapid |
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Term
| With pathway specific allosteric effectors, is product a (+) or (-) effector? |
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Definition
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Term
| With pathway specific allosteric effectors, is substrate a (+) or (-) effector? |
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Definition
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Term
| What are common allosteric effectors? |
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Definition
| These effectors signal the overall metabolic state of the cell. |
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Term
| Name 3 common allosteric effectors whose signal indicates the cell needs more energy |
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Definition
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Term
| What effect does AMP/ADP, NADP, NAD+ have on the metabolic state of a cell? |
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Definition
| Indicates that the cell needs more energy. This leads to activation of catabolic/energy generating pathways |
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Term
| Name four common allosteric effectors that indicate that the cell has plenty of energy. |
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Definition
| ATP, NADPH, NADH, citrate |
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Term
| Does ATP activate or inhibit anabolic/storage pathways? Why |
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Definition
| Activates because there is enough, or too much, ATP available. It doesn't need to make any more. |
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Term
| Name two forms of free energy and the molecules that carry them both. |
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Definition
| Bond energy and redox potential energy are two forms of free energy carried by ATP and NADH/NADPH |
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Term
| What do molecules need to undergo reaction (energy-wise) |
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Definition
| They need enough Kinetic Energy to undergo reaction |
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Term
| What is the affect of raising activation energy on the number of molecules able to undergo reaction? |
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Definition
| It decreases the number of molecules able to undergo reaction |
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Term
[image]
What direction would an enzyme shift the red arrow? |
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Definition
| to the left, increasing the number of molecules with enough energy to participate in the reaction |
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Term
| Why is it good that regulatory steps have a large negative(delta)G? |
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Definition
| Because the reverse reaction will not proceed unaided and only the forward reaction will occur. |
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Term
| What is required for a reaction to proceed that has a positive delta G? |
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Definition
| These reactions need to be primed. They need energy in the form of ATP or somewhere to get over the activation energy hump. |
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Term
| What are priming reactions? |
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Definition
| Reactions that involve the consumption of energy to prepare the substrate for the next step in the pathway. |
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Term
| Do non spontaneous reactions have a positive or negative delta G? |
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Definition
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Term
| If many reactions within a cell are non spontaneous, then how can a cell carry out these necessary reactions? |
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Definition
| By coupling it to a reaction with a negative delta G of larger magnitude. |
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Term
| Explain how free energies are additive. |
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Definition
| The free energy of one reaction adds to the free energy of another. If one reaction has a positive delta G and another has a much larger negative delta G, the sum will be a small negative delta G. |
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Term
| What frequently acts as the energy source for positive delta G reactions? |
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Definition
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Term
| What bonds are used in ATP hydrolysis to power metabolism? |
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Definition
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Term
| Why do phosphoanhydride bonds contain and store large amounts of energy? |
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Definition
| Because of competing resonance |
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Term
| The difference in magnitude of the delta Gs between coupled reactions is lost as _________? |
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Definition
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Term
| Give two examples of direct coupling |
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Definition
| Redox reactions and steps 6&7 of glycolysis |
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Term
| Explain how a metabolic pathway may be coupled without the involvement of energy. |
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Definition
| The first reaction makes an unfavorable product that is immediately used by another reaction as the reactant for a favorable product. |
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Term
| An energy yielding reaction is anabolic or catabolic? |
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Definition
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Term
| An energy consuming reaction is anabolic or catabolic? |
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Definition
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Term
| Why is fat considered high energy storage? |
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Definition
| Because the biosynthesis of fats requires the formation of many C-C bonds and hence stores a lot of energy |
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Term
| Is oxidation energy storing or energy releasing reaction? |
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Definition
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Term
| What is being transferred in redox reactions? |
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Definition
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Term
| Oxidation is loss or gain of electrons? |
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Definition
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Term
| reduction is loss or gain of electrons? |
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Definition
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Term
| In redox reactions in cells, electrons are not seen to be explicitly transferred. What is? |
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Definition
| Hydrogen atoms (protons plus electrons) |
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Term
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Definition
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Term
| What are common electron shuttle molecules? |
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Definition
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Term
| Where is energy stored in high energy electrons stored in NADPH typically used? |
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Definition
| Used in biosynthetic pathways |
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Term
| Where on NADH and NADPH are electrons held? |
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Definition
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Term
| Name the three forms of free energy seen in metabolism. |
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Definition
| Bond energy, redox potential energy, electrochemical potential energy |
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Term
| Where is free energy stored with electrochemical potential energy |
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Definition
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Term
| Where is electrochemical potential energy used to make ATP? |
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Definition
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Term
| What connects anabolism and catabolism? |
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Definition
| Free energy carriers such as ATP and NADPH |
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