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une ch 9
regulation on enzymes
| Question | Answer |
|---|---|
| What is the Michaelis-Menten equation? | vi = (Vmax [S]) / (Km + [S]) |
| vi = | the initial velocity - the initial rate of the reaction at a certain substrate concentration, (the first few seconds of a reaction). |
| Vmax = | the maximal velocity (rate) a reaction can achieve at an infinite concentration of substrate. |
| Km = | Km is the substrate concentration at which the reaction rate is at half-maximum and is a measure of the substrate's affinity for the enzyme. |
| A small Km indicates | high affinity, meaning that the rate will approach Vmax at lower concentrations of substrate. |
| [S] = | substrate concentration (the rate of the reaction is dependent on the amount of substrate). |
| Be able to write and state in words the reaction for the most common mechanism that uses NAD+ as a cofactor. | Ethanol + NAD+ ---> Acetaldehyde + NADH + H+ Or, CH3CH2OH + NAD+ ---> CH3CHO + NADH + H+ |
| say the Vmax of cytosolic alcohol dehydrogenase enzyme and the MEOS are equal in Al's liver and that the Km's are 0.04 mM and 11 mM, respectively. Which will oxidize most of the alcohol? i.e after 1 oz of alcohol and a blood alcohol of 6.4 mM. Why? | 6.4 mM is only at 58% of the 11 mM Km for the MEOS system. Therefore, this enzyme is operating at less than ½ Vmax. 6.4 is 160x the concentration 0.04 mM Km for the cytosolic alcohol dehydrogenase. Therefore, this enzyme is operating at close to its Vmax |
| sequence of glycogenolysis activated by adrenalin | Increased epinephrine __> active G-Protein __> active adenylate cyclase __> increased [cAMP] __> active Protein kinase A __> active Glycogen phosphorylase kinase __> active Glycogen phosphorylase_> Gly phosphor B to A_>gly phosphor a can remove g1p |
| Understand the effect that allosteric activators have on the conformation of an allosteric enzyme and on the plot of velocity versus substrate concentration. What about the S0.5? | stabilized the R-state, i.e., the high affinity for substrate state conformation slide the sigmoidal curve to the left. lower the S0.5 |
| Understand the effect that allosteric inhibitors have on the conformation of an allosteric enzyme and on the plot of velocity versus substrate concentration. What about the S0.5? | stabilized the T-state, i.e., the low affinity for substrate state conformation slide the sigmoidal curve to the right. increase the S0.5 |
| explain Muscle action potential and phosphorylase kinase" | Ca2+ to calmodulin to form a Ca2+- calmodulin complex. Ca2+- calmodulin complex activates Glycogen phosphorylase kinase _>phosphorylates Glyco phosphor b converting it to the active form, Glyco phosphor a. |
| explain how either AMP or phosphorylase kinase activates muscle glycogen phosphorylase | AMP, a positive allosteric effector, must bind glycogen phosphorylase b, and/or, glycogen phosphorylase kinase must phosphorylate a serine residue on glycogen phosphorylase b |
| Are chymotrypsinogen and prothrombin zymogens? How are these enzymes activated? | yes. Zymogens: precursor proteins of proteases. Zymogens are activated by proteolytic cleavage, which is the process of cleaving the zymogen into pieces by hydrolysis of peptide bonds. Chymotrypsinogen2chymotrypsin and prothrombin2thrombin. |
| Why is it important that the regulatory (control) enzyme for a pathway, catalyze the rate limiting step in a pathway? | The control enzyme has the ability to increase or decrease the rate of the pathway by changing its enzyme activity. |
| The rate of the control enzyme may be changed by: | Availability of substrate, Product inhibition,conformational changes, Feedback inhibition,Enzyme induction,Enzyme repression |
| what pathway is used when her cells wants to make energy from glucose-6-phosphate and how does the concentration of ATP or AMP in the cell affect the rate of this pathway? Is ATP a feedback inhibitor? | Glycolysis is the pathway used to make energy from glucose-6-phosphate and the control enzyme for the pathway is Phosphofructokinase-1 AMP increases the rate of glycolysis and ATP inhibits the rate of glycolysis. |
| what pathway does she use for the storage of glucose as glycogen? How do glucose concentration and insulin affect this pathway? | Glycogen Synthesis (a.k.a. glycogenesis) is the pathway she uses for the storage of glucose as glycogen. High glucose & insulin concentrations activate this pathway in the liver and in the muscle cells. |
Created by:
carolanimal
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