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Regulation of Glycolysis and Gluconeogenesis, Exams of Nursing

A detailed overview of the regulation of glycolysis and gluconeogenesis, two fundamental metabolic pathways in the human body. It covers key concepts such as the role of protein kinases, allosteric regulation, feedback inhibition, and reciprocal regulation in controlling the activity of enzymes involved in these pathways. The document also discusses the importance of maintaining blood glucose levels and the differences in regulatory mechanisms between liver and muscle cells. By understanding the complex regulatory mechanisms governing glycolysis and gluconeogenesis, students can gain insights into how these pathways are fine-tuned to meet the body's energy demands and maintain homeostasis.

Typology: Exams

2023/2024

Available from 07/18/2024

Toperthetop
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BCMB 401 Homework 5,6,

what amino acid does NOT have a side chain (R group) that could be phosphorylated in a reaction catalyzed by protein kinase? tryptophan protein kinase and protein phosphates both... catalyze reactions that are very energetically favorable (in the forward direction) protein kinase A is inactive when regulatory subunits are bound to the catalytic subunits because a pseudo substrate (autoinhibitory) sequence blocks substrate binding an amino acid residue phosphorylated by protein kinase A would be most likely to be found on a(n) loop in the consensus sequence on protein substrates recognized by protein kinase A, RRx(S/T)hyd, the two arginine residues interact with ________ residues on protein kinase A to correctly position the S or T for phosphorylation. three glutamate in the consensus sequence on protein substrates recognized by protein kinase A, RRx(S/T)hyd, the hydrophobic residues (hyd) interacts with ________ residues on protein kinase A to correctly position the S or T for phosphorylation.

two leucine a molecule that binds to a receptor in a signal transduction cascade and blocks activation of the receptor would be considered a(n) antagonist a signaling molecule generated inside the cell as part of a signal transduction cascade would be considered a(n) second messenger heterotrimeric G protein binding to the cytoplasmic part of an epinephrine-bound B-adrenergic receptor leads to a molecule of GDP dissociating from Galpha followed by a molecule of GTP binding to Galpha Galpha can only activate adenylate cyclase when it has GTP bound because GTP binding to Galpha cause B and Y to dissociate. B and Y block the site on Galpha that interacts with adenylate cyclase in cardiac muscle cells, protein kinase A phosphorylates troponin 1 causing a structural change in this protein. Phosphorylated troponin 1... has weaker binding to actin which speeds up the contraction/relaxation cycle in cardiac muscle the "timed switch" that inactivated an individual Galpha involves.... a molecule of GTP being dephosphorylated to become a molecule of GDP

what is the correct description for receptor desensitization in B-adrenergic receptor signaling? B-adrenergic receptor kinase phosphorylates cytoplasmic loops of B-adrenergic receptor, recruiting B- arrestin and blocking Galpha activation four insulin molecules binding to the alpha subunits of the insulin receptor... bring the beta subunits together partially activating the tyrosine kinase activity of the insulin receptor full activation of in the tyrosine kinase activity of the insulin receptor requires... cross-phosphorylation of the activation loop by the other beta subunits which locks the activation loop in a position away from the active site in the insulin receptor pathway, phosphorylation of IRS-1 is necessary to bind phosphoinositide-3-kinase (PI3 kinase) because the interaction between IRS-1 and PI3 kinase involves... salt bridges between the phosphotryosine on IRS-1 and two arginine residues on PI3 kinase PI3 kinase binding to IRS-1 is necessary for the signal transduction cascade because it brings PI3 kinase to the membrane so that PI3 kinase can phosphorylate its lipid substrate in muscle and adipose cells, activated Akt (protein kinase B) will lead go a(n) ______ in the amount of glucose transporters in the plasma membrane of the cell. increase

in the induced fit mechanism for hexokinase, the amino acids in the active site are not correctly positioned to catalyze the reaction until after ______ binds glucose triose phosphate isomerase deficiency is caused by mutations that result in an impaired or non- functional triose phosphate isomerase enzyme. non-functional triose phosphate isomerase would result in _______ production of ATP and _____ production of NADH in glycolysis decrease decrease in the reaction catalyzed by glyceraldehyde 3-phosphate dehydrogenase... an energetically unfavorable reaction intermediate is formed, decreasing the activation energy barrier in the second part of the reaction a high phosphoryl transfer potential compound is a molecule that... has a very negative deltaG value giving up a phosphate, meaning it is very energetically favorable for a phosphate to be removed from the molecule a total of ____ net ATP (produced minus invested) molecules are produced in the conversion of one molecule of glucose to two molecules of pyruvate 2 fermentation is necessary during anaerobic conditions because NADH cannot give up its electrons to electron transport in the absence of oxygen

lactic acid fermentation in the muscle is only sustained for a short amount of time because it utilizes small amounts of glucose, so it will quickly deplete glucose in the cell red blood cells only can use lactic acid fermentation for energy production because red blood cells do not have mitochondria in the reaction catalyzed by the enzyme pyruvate carboxylase, the favorable free energy of ATP hydrolysis is used to form carboxyphosphate. the carboxyl group from carboxyphosphate is transferred to biotin to form carboxybiotin. in the pyruvate carboxylase reaction, the substrate that binds to the active site in the carboxyl transferase (CT) domain is pyruvate converting oxaloacetate to phosphoenolpyruvate requires an energetically favorable decarboxylation and a phosphoryl transfer from GTP if glucose is not being transported out of the liver cell, the high concentration of glucose in the cytoplasm will... decrease glucose transport from the endoplasmic reticulum (ER) to the cytoplasm. an increase in glucose in the ER will eventually cause the glucose 6-phosphatase reaction to have a positive deltaG value a total of ___ ATP equivalents (total ATP + GTP molecules) are required to produce one molecule of glucose from two molecules of pyruvate

gluconeogenesis will ______ when glycerol is the precursor compared to when lactate is the non- carbohydrate precursor. be less energetically costly regulation of glycolysis involves regulation of enzymes that catalyze _____ steps in the pathway irreversible for the enzyme phosphofructokinase (PFK-1), a high concentration of AMP in the cell will upregulate the enzyme by shifting the curve to the left for the enzyme phosphofructokinase (PFK-1), a high concentration of ATP in the cell will downregulate the enzyme by shifting the curve to the right for the enzyme PFK-1, a high H+ concentration (low pH) will enhance the allosteric effect of ATP on PFK activity the effect of glucose 6-phosphate on hexokinase activity in muscle cells is an example of feedback inhibition. feedback inhibition occurs when a molecule that is present later in the pathway downregulates an enzyme that catalyzes a reaction earlier in the pathways

the effect of fructose 1,6-bisphosphate on pyruvate kinase activity is an example of feed-foward stimulation. feed-forward stimulation occurs when a molecule that is present earlier in the pathway regulates an enzyme that catalyzes a reaction later in the pathway in the liver, pyruvate kinase activity is regulated by alanine. a high concentration of alanine in the liver is a sign that proteins are being broken down to provide glucose for the bloodstream and will shift the pyruvate kinase activity curve to the right (increase L) reciprocal regulation occurs when one molecule (or one set of conditions) has the opposite regulatory effect on two different pathways. the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, catalyzed by the enzyme fructose 1,6-bisphosphatase, is the key regulated step in gluconeogenesis because the phosphoenolpyruvate (PEP) carboxykinase reaction is reversible and the pyruvate carboxylase reaction is not unique to gluconeogenesis although important, regulation by energy levels (ATP/AMP) is less important in the liver than it is in the muscle. this difference occurs because there are ________ fluctuations in ATP levels in liver (compared to muscle) and also because the liver has an important role in maintaining _______ smaller blood glucose levels in the liver, insulin signaling will lead to activation of ________ which ________ the PFK2/FbPase bifunctional enzyme which activates ______ activity of the bifunctional enzyme leading to a(n) ______ in fructose 2,6-bisphosphate levels in the liver cell.

phosphoprotein phosphatase dephosphorylates PFK increase in the liver, glucagon signaling will lead to activation of ________ which ________ the PFK2/FbPase bifunctional enzyme which activates ______ activity of the bifunctional enzyme leading to a(n) ______ in fructose 2,6-bisphosphate levels in the liver cell. protein kinase A phosphorylates FbPase decrease in the liver, a high concentration of fructose 2,6-bisphosphate will shift the activity curve of fructose 1,6- bisphosphatase to the right in the liver, a signal transduction cascade initiated when glucagon binds the glucagon receptor will lead to activation of protein kinase A which phosphorylates pyruvate kinase and makes pyruvate kinase less active a low concentration of glucose or a high concentration of fructose 6-phosphate in the liver will cause glucokinase to move to the nucleus where it will associate with glucokinase regulatory protein (GKRP) and become inactive

a high concentration of glucose in the liver will cause glucokinase to be released from glucokinase regulatory protein (GKRP) so that it can move from the nucleus to the cytoplasm to be able to catalyze the first reaction in glycolysis