Classify the phrases. Does each phrase describe a kinase, a phosphatase, neither, or both? Kinases Phosphatases Answer Bank Neither Both may use ATP as a phosphoryl group donor PKA (protein kinase A) is an example regulate the activity of other proteins catalyze dephosphorylation reactions in eukaryotes, transfer phosphoryl groups to acidic amino acids catalyze reactions that are the reverse of dephosphorylation reactions add phosphoryl groups to proteins turn off signaling pathways triggered by kinases

Classify the phrases. Does each phrase describe a kinase, a phosphatase, neither, or both? Kinases Phosphatases Answer Bank Neither Both may use ATP as a phosphoryl group donor PKA (protein kinase A) is an example regulate the activity of other proteins catalyze dephosphorylation reactions in eukaryotes, transfer phosphoryl groups to acidic amino acids catalyze reactions that are the reverse of dephosphorylation reactions add phosphoryl groups to proteins turn off signaling pathways triggered by kinases

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter18: Glycolysis

Section: Chapter Questions

Problem 21P

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Assessing the Effect of Active-Site Phosphorylation on Enzyme Activity (Integrates with Chapter 15.) The serine residue of isocitrate dehydroenase that is phosphorylated by protein kinase lies within the active site of the enzyme. This situation contrasts with most other examples of coa1ent modification by protein phosphorylation. where the phosphorylation occurs at a sate remote from the active site. What direct effect do you think such active-site phosphorylation might have on the catalytic activity of isocitrate dehydrogcn.ise? (Sec Barford, D., 1991. Molecular mechanisms for the control of enzymic activity by protein phosphorytation. Biochimica et Biophysica Acta 1133:55â€”62.)
Using the answer code on the right, indicate which form of energy production is being described: 1. takes place in the mitochondrial matrix 2. produces H2O as a by-product 3. results in a rich yield of ATP 4. takes place in the cytosol 5. processes acetyl-CoA 6. takes place in the mitochondrial innermembrane cristae 7. converts glucose into two pyruvate molecules 8. uses molecular oxygen 9. accomplished by the electron transport system and ATP synthase (a) glycolysis (b) citric acid cycle (c) oxidative phosphorylation
Imagine that you are working with isolated mitochondria and you manage to double the ratio of protons outside to protons inside. In order to maintain the overall Gat its original value (whatever it is), how would you have to change the mitochondria membrane potential?
The Relative Efficiency of ATP Synthesis in Noncyclic versus Cyclic Photophosphorylation If noncyclic photosynthetic electron transport leads to the translocation of 7 H+/2e- and cyclic photosynthetic electron transport leads to the translocation of 2 H+/e-, what is the relative photosynthetic efficiency of ATP synthesis (expressed as the number of photons absorbed per ATP synthesized) for noncyclic versus cyclic photophosphorylation? (Assume that the CF1CF0-ATP synthase yields 3 ATP/14 H+.)
pH and in the Chloroplast Proton-Motive Force (Integrates with Chapter 20.) In mitochondria, the membrane potential () contributes relatively more to p (proton-motive force) than does the pH gradient (pH). The reverse is true in chloroplasts. Why do you suppose that the proton-motive force in chloroplasts can depend more on pH than mitochondria can? Why is () less in chloroplasts than in mitochondria?
Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy charge. a. Would hexokinase be an R enzyme or a U enzyme? Would glutamine: PRPP amidotransferase, the second enzyme in purine biosynthesis, be an R enzyme or a U enzyme? b. If energy charge = 0.5: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low? c. If energy charge = 0.95: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low?
When glucose reacts with ATP to form glucose-6-phosphate: a. the synthesis of glucose-6-phosphate is exergonic. b. ADP is at a higher energy level than ATP. c. glucose-6-phosphate is at a higher energy level than glucose. d. because ATP donates a phosphate to glucose, this is not a coupled reaction. e. the reaction is spontaneous.
PREDICT In the following reaction series, which enzyme(s) is/are most likely to have an allosteric site to which the end product E binds? (a) enzyme 1 (b) enzyme 2 (c) enzyme 3 (d) enzyme 4 (e) enzymes 3 and 4
Which of the following analogies best describes the induced-fit model of enzyme-substrate binding? a hug between two people a key fitting into a lock a square peg fitting through the square bole and a round peg fitting through the round hole of a children’s toy the fitting together of two jigsaw puzzle pieces
Energetic of Fructose-1 ,6-bis P Hydrolysis (Integrates with Chapter 3.) The standard free energy change (G) for hydrolysis of fructose-1. 6-bisphosphate (FBP) to fructose-S-phosphate (F-6-P) and P: is -16.7 KJ/mol: FBP + H2O fructose-6-P + Pi The standard free energy change (G) for ATP hydrolysis is -30.5 KJ/mol: ATP + H2O ADP + Pj What is the standard free energy change for the phosphofructokinase reaction: ATP + fructose-6-P ADP + FBP b. What is the equilibrium constant for this reaction? c. Assuming the intracellular concentrations of [ATP] and (ADP] are maintained constant at 4 mM and 1.6 mM, respectively, in a rat liver cell, what will be the ratio of [FBP]/[fructose-6-P] when the phosphofructokinase reaction reaches equilibrium?
Figure 9.8 HER2 is a receptor tyrosine kinase. In 30 percent of human breast cancers, HER2 is permanently activated, resulting in unregulated cell division. Lapatinib, a drug used to treat breast cancer, inhibits HER2 receptor tyrosine kinase autophosphorylation (the process by which the receptor adds phosphates onto itself), thus reducing tumor growth by 50 percent. Besides autophosphorylation, which of the following steps would be inhibited by Lapatinib? Signaling molecule binding, dimerization, and the downstream cellular response. Dimerization, and the downstream cellular response. The downstream cellular response. Phosphatase activity, dimerization, and the downsteam cellular response.
What is the function of a phosphatase? A phosphatase removes phosphorylated amino acids from proteins. A phosphatase removes the phosphate group from phosphorylated amino acid residues in a protein. A phosphatase phosphorylates serine, threonine, and tyrosine residues. A phosphatase degrades second messengers in the cell.