Energy Metabolism Regulation and Creatine Chemistry
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Questions and Answers

The conversion of creatine to creatinine is an enzymatic process.

False (B)

Creatinine clearance (CrCl) is used to estimate the ______, a measurement of renal function.

glomerular filtration rate (GFR)

Which of these factors can increase daily creatinine excretion?

  • Reduced muscle mass
  • Decreased dietary intake of creatine
  • Increased dietary intake of creatine (correct)
  • Decreased consumption of protein

    • What is the primary function of glycogen in the body?

    <p>Energy storage</p> Signup and view all the answers

    Which of these is NOT a factor that can cause an elevated creatinine level?

    <p>Increased tubular secretion of creatinine (B)</p> Signup and view all the answers

    Match the following terms with their corresponding definitions:

    <p>Glycogen = A branched biopolymer of glucose Creatinine = A waste product produced from muscle metabolism GFR = The rate at which blood is filtered by the kidneys α(1→4) glycosidic bonds = The type of bond that links glucose units in linear glycogen chains α(1→6) glycosidic bonds = The type of bond that forms branches in glycogen</p> Signup and view all the answers

    Glycogen is synthesized by a protein called glycogenin.

    <p>True (A)</p> Signup and view all the answers

    What are the two main forms of long-term energy reserves in the body?

    <p>Glycogen and triglyceride stores in adipose tissue</p> Signup and view all the answers

    What is the primary role of phosphocreatine in the body?

    <p>To serve as a high-energy reserve for ATP regeneration (C)</p> Signup and view all the answers

    Excess ATP cannot be converted back to creatine.

    <p>False (B)</p> Signup and view all the answers

    What indicates tissue damage and is used in the diagnosis of myocardial infarction?

    <p>Creatine kinase (CK-MB)</p> Signup and view all the answers

    Creatinine is primarily cleared from the body through the ______.

    <p>urine</p> Signup and view all the answers

    Where is creatine synthesized in the body?

    <p>Liver (C)</p> Signup and view all the answers

    Creatinine is a breakdown product of creatine phosphate in muscle.

    <p>True (A)</p> Signup and view all the answers

    What happens to blood creatinine levels if kidney filtration is deficient?

    <p>Blood creatinine concentrations rise.</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Phosphocreatine = High-energy reservoir for ATP regeneration Creatinine = Waste product cleared through urine Creatine Kinase = Enzyme indicative of tissue damage S-Adenosyl Methionine = Compound involved in creatine synthesis</p> Signup and view all the answers

    What is the first step in glycogen degradation?

    <p>Release of glucose 1-phosphate from glycogen (C)</p> Signup and view all the answers

    Glucose 6-phosphate can only be used in glycolysis.

    <p>False (B)</p> Signup and view all the answers

    What activated form of glucose is required for glycogen synthesis?

    <p>UDP-glucose</p> Signup and view all the answers

    The hormone signaling in glycogen metabolism regulates _____ of enzymes.

    <p>phosphorylation</p> Signup and view all the answers

    Match the fates of glucose 6-phosphate with their descriptions:

    <p>Glycolysis = Initial substrate for producing energy Pentose phosphate pathway = Produces NADPH and ribose derivatives Free glucose conversion = Released into the bloodstream</p> Signup and view all the answers

    Which of the following is NOT a fate of glucose 6-phosphate?

    <p>Converted into fat storage (A)</p> Signup and view all the answers

    Glycogen metabolism is solely regulated by allosteric responses.

    <p>False (B)</p> Signup and view all the answers

    What allows glycogen degradation to integrate with glycogen synthesis?

    <p>Allosteric regulation and hormonal cascades</p> Signup and view all the answers

    What is the primary function of creatine phosphate in the body?

    <p>To recycle ATP (B)</p> Signup and view all the answers

    Creatine phosphate can only be found in the muscle cells.

    <p>False (B)</p> Signup and view all the answers

    What two amino acids are converted into guanidinoacetate (GAA) in the kidneys?

    <p>arginine and glycine</p> Signup and view all the answers

    Creatine phosphate is transformed into phosphocreatine by the enzyme __________.

    <p>creatine kinase</p> Signup and view all the answers

    Which enzyme adds a methyl group to guanidinoacetate?

    <p>GAMT (B)</p> Signup and view all the answers

    Match the following substances with their roles:

    <p>Creatine = Stored energy ADP = Precursor to ATP Guanidinoacetate = Intermediate in creatine synthesis Creatinine = Byproduct excreted in urine</p> Signup and view all the answers

    A 70 kg man contains approximately __________ grams of creatine.

    <p>120</p> Signup and view all the answers

    What percentage of creatine in the body is found as creatine phosphate?

    <p>60%</p> Signup and view all the answers

    What is the primary enzyme responsible for the breakdown of glycogen?

    <p>Glycogen phosphorylase (A)</p> Signup and view all the answers

    Muscle cell glycogen can be released into the bloodstream to provide glucose to other cells.

    <p>False (B)</p> Signup and view all the answers

    What hormone counteracts the effects of insulin and stimulates glycogen breakdown?

    <p>glucagon</p> Signup and view all the answers

    Glycogen is stored in cells in a hydrated form, associated with approximately 0.45 millimoles of _______ per gram of glycogen.

    <p>potassium</p> Signup and view all the answers

    Match the following hormones with their primary effects on glycogen:

    <p>Insulin = Reduces blood glucose levels Glucagon = Increases blood glucose levels</p> Signup and view all the answers

    What happens to the glucose taken up by liver cells in a postprandial state?

    <p>It is stored as glycogen. (C)</p> Signup and view all the answers

    Glycogen is an osmotic molecule and can disrupt cellular osmotic pressure.

    <p>False (B)</p> Signup and view all the answers

    What process is stimulated by glucagon in order to increase blood glucose levels?

    <p>glycogenolysis and gluconeogenesis</p> Signup and view all the answers

    Study Notes

    Regulation of Energy Metabolism

    • This presentation covers creatinine, creatinine phosphate, and glycogen, all vital parts of energy metabolism.
    • Subtopics include the brain's energy metabolism, glucagon and insulin, and fermentative and aerobic metabolism.
    • Creatine phosphate (CP) or PCr (phosphocreatine) is a phosphorylated creatine molecule. It acts as a rapidly mobilizable reserve of high-energy phosphates in muscle and the brain. This reserve recycles ATP (adenosine triphosphate).

    Creatine Phosphate Chemistry

    • Creatine phosphate is made from two amino acids-arginine and glycine, catalyzed by the enzyme AGAT.
    • Guanidinoacetate (GAA) is formed then transported to the liver.
    • A methyl group is added from methionine using the GAMT enzyme, forming unphosphorylated creatine.
    • Creatine is released into the blood and is taken up mainly by muscle cells (95%).
    • Inside the cell, unphosphorylated creatine is transformed into phosphocreatine via the enzyme complex, creatine kinase.
    • The human body recycles its body weight in ATP daily through creatine phosphate.

    Creatinine Chemistry

    • Creatine phosphate decomposes into creatinine, which is excreted in urine.
    • A 70 kg man typically has 120 grams of creatine, with 40% as unphosphorylated creatine and 60% as creatine phosphate.
    • 1-2% of that amount is broken down and excreted daily as creatinine.

    Creatinine Functions

    • Phosphocreatine anaerobically donates a phosphate group to ADP to form ATP during intense muscular or neuronal activity (first 2-7 seconds).
    • Excess ATP is used to convert creatine to phosphocreatine during periods of low effort.
    • Creatine kinase (CK-MB) in blood plasma indicates tissue damage, used in myocardial infarction diagnosis. A cell's ability to generate phosphocreatine from excess ATP (at rest) and repurpose it (during activity) helps buffer ATP concentration.

    Glycogen Introduction

    • Glycogen is a multibranched polysaccharide of glucose.
    • It serves as a primary energy storage form in the body.
    • Triglycerides in adipose tissue are the other main energy reservoir.

    Glycogen Structure

    • Glycogen is a branched biopolymer of glucose residues.
    • Chains are linked linearly by α(1→4) glycosidic bonds.
    • Branches are connected by α(1→6) glycosidic bonds.
    • Every glycogen granule has a glycogenin protein core.

    Glycogen Functions

    • As a meal is eaten, blood glucose rises and the pancreas secretes insulin.
    • Glucose in the portal vein enters liver cells (hepatocytes).
    • Insulin activates several enzymes, including glycogen synthase, allowing glucose to attach to glycogen molecules, storing it.
    • The liver takes in more glucose than releases during the post-meal "fed" state.
    • When blood glucose levels drop (after a meal), insulin secretion reduces.
    • Glycogen is broken down and converted back to glucose by glycogen phosphorylase.
    • Liver glycogen is the primary glucose source for the rest of the body for the next 8-12 hours.
    • Muscle glycogen functions as an immediate stored glucose source only for the muscle cells.

    Glycogen Metabolism

    • Glycogen degradation proceeds in three steps: releasing glucose-1-phosphate, remodeling glycogen, and converting glucose-1-phosphate to glucose-6-phosphate.
    • Glucose 6-phosphate can be: used for glycolysis, enter the pentose phosphate pathway (for NADPH and ribose), or converted to glucose to be released into the bloodstream.
    • Glycogen synthesis involves UDP-glucose, which is formed by UTP and glucose 1-phosphate. UDP-glucose attaches to the non-reducing end of glycogen molecules.
    • Glycogen metabolism is complex, with allosteric modulation (responding to metabolites) and hormonal regulation—this regulation assures glycogen synthesis and breakdown work in tandem based on the body's needs.

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    Regulation of Energy Metabolism PDF

    Description

    Explore the regulation of energy metabolism focusing on creatinine, creatine phosphate, and glycogen. This quiz delves into their roles in energy production, including insights on how the brain utilizes these substances and the biochemical pathways involved in creatine synthesis.

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