Amino Acid Degradation and Metabolism
40 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What condition results from defects in the conversion of ammonia to urea?

  • Hyperkalemia
  • Hypoglycemia
  • Hyperammonaemia (correct)
  • Hypernatremia

    • Which enzyme deficiency is associated with severe neonatal disorder and fatal consequences?

  • Ornithine Transporter
  • Arginase
  • CPS-I
  • N-Acetylglutamate Synthase (correct)

    • What is the primary consequence of increased ammonia levels in the brain?

  • Increased production of α-ketoglutarate
  • Decreased utilization of α-ketoglutarate
  • Impaired TCA cycle functionality (correct)
  • Increased ATP production

    • What condition is characterized by hyper-ornithinemia, hyperammonemia, and homocitrillinuria?

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

    What is the role of S-adenosylmethionine (SAM) in methionine metabolism?

    <p>It provides methyl groups for methyltransferases (D)</p> Signup and view all the answers

    What can result from methionine metabolism beyond cysteine production?

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

    What neurological symptoms can result from hyperammonaemia?

    <p>Slurring of speech (A)</p> Signup and view all the answers

    Which enzyme action alters DNA accessibility through modification of histone proteins?

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

    What is the first product formed in the urea cycle?

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

    Which of the following compounds is NOT a substrate for Carbamoyl phosphate synthetase I (CPS I)?

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

    Which enzyme requires N-acetylglutamate (NAG) for its activity?

    <p>Carbamoyl phosphate synthetase I (B)</p> Signup and view all the answers

    What is the primary nitrogen source in the synthesis of urea from the urea cycle?

    <p>Amino group from aspartic acid (A), Ammonia (D)</p> Signup and view all the answers

    Which step in the urea cycle is considered rate-limiting?

    <p>Formation of Carbamoyl phosphate (B)</p> Signup and view all the answers

    What is the end product of the protein metabolism process involving the urea cycle?

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

    From which organ are urea molecules transported for excretion?

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

    What is the major difference between Carbamoyl phosphate synthetase I (CPS I) and Carbamoyl phosphate synthetase II (CPS II)?

    <p>CPS I is found in the mitochondria, while CPS II is found in the cytosol. (A)</p> Signup and view all the answers

    What is one primary way ammonia (NH4+) is handled in the body following amino acid degradation?

    <p>Incorporated into nucleotides (B)</p> Signup and view all the answers

    Which statement is true regarding the amino acid pool in the body?

    <p>It contains about 100g of amino acids total (A)</p> Signup and view all the answers

    What role do certain amino acids play beyond being building blocks for proteins?

    <p>They can function as neurotransmitters (B)</p> Signup and view all the answers

    Which of the following best describes the dynamics of protein turnover in the body?

    <p>Protein turnover is constant, about 300-400g daily (C)</p> Signup and view all the answers

    How are essential amino acids generally obtained by animals?

    <p>Obtained through dietary intake (B)</p> Signup and view all the answers

    What is the relationship between tyrosine and phenylalanine in the body?

    <p>Tyrosine can be synthesized from phenylalanine (C)</p> Signup and view all the answers

    What distinguishes essential amino acids from nonessential amino acids?

    <p>Essential amino acids require more enzymatic reactions for synthesis (C)</p> Signup and view all the answers

    Which molecule can arginine be derived from in the body?

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

    Which amino acids do not participate in transamination?

    <p>Proline (A), Threonine (B), Lysine (C)</p> Signup and view all the answers

    What is the first step in the mechanism of transamination?

    <p>Formation of pyridoxamine phosphate (A)</p> Signup and view all the answers

    Where does transamination predominantly occur?

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

    Which enzyme is specifically found in the liver mitochondria to perform oxidative deamination?

    <p>Glutamate dehydrogenase (D)</p> Signup and view all the answers

    What compound does glutamate dehydrogenase produce during oxidative deamination?

    <p>α-ketoglutarate (B), Ammonia (D)</p> Signup and view all the answers

    What is a consequence of cellular damage in relation to enzymatic activity?

    <p>Elevated AST levels may indicate myocardial infarction (A)</p> Signup and view all the answers

    Which of the following describes the role of glutamate in amino acid metabolism?

    <p>It acts as a 'collection center' for amino groups (A)</p> Signup and view all the answers

    What is the main purpose of oxidative deamination?

    <p>To provide free ammonia for urea synthesis (B)</p> Signup and view all the answers

    What substance accumulates in the urine of individuals with PKU due to the enzyme deficiency?

    <p>Phenylpyruvic acid (D)</p> Signup and view all the answers

    What is the inheritance pattern of Phenylketonuria (PKU)?

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

    Who first described Phenylketonuria and related it to the urine's musty odor?

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

    Which gene mutation is directly associated with Phenylketonuria?

    <p>PAH gene (D)</p> Signup and view all the answers

    What is one of the common symptoms of PKU?

    <p>Musty odor in breath or urine (D)</p> Signup and view all the answers

    What dietary management is typically used to treat PKU?

    <p>Low-protein diet (B)</p> Signup and view all the answers

    What is a characteristic physical feature associated with PKU?

    <p>Fair skin and blue eyes (D)</p> Signup and view all the answers

    What is a potential consequence of not adhering to the dietary restrictions for PKU?

    <p>Worsening of physical and mental health (C)</p> Signup and view all the answers

    Study Notes

    Amino Acid Degradation

    • Amino acid degradation results in ammonium (NH4+) and carbon skeletons.
    • NH4+ can be converted into nitrogen-containing compounds like nucleotides or excreted as urea.
    • Carbon skeletons can enter TCA cycle intermediates for ATP production, fatty acid synthesis, or gluconeogenesis.

    Functions of Amino Acids

    • Certain amino acids act as neurotransmitters, including glycine, aspartate, and glutamate.
    • The body contains approximately 100g of free amino acids as an amino acid pool.
    • Glutamate and glutamine make up about 50% of the amino acid pool; essential amino acids account for around 10%.
    • Intracellular amino acid concentration exceeds that of extracellular; cellular uptake occurs against a concentration gradient.

    Sources and Turnover of Amino Acids

    • The amino acid pool is maintained through dietary protein intake and synthesis of non-essential amino acids.
    • Body protein turnover involves 300-400g of protein being constantly degraded and synthesized daily.

    Essential and Nonessential Amino Acids

    • Essential amino acids must be obtained through diet; they have more complex structures and require numerous enzymatic reactions for synthesis.
    • Conditional essential amino acids include tyrosine (derived from phenylalanine) and arginine (partially synthesized from argininosuccinate).

    Transamination Mechanism

    • Transamination involves transferring the amino group from an amino acid to an α-keto acid, producing a new amino acid and a keto acid.
    • The process utilizes pyridoxal phosphate (PLP) as a coenzyme, facilitating amino group transfer.

    Transamination and Deamination

    • Transamination occurs in the cytoplasm, converting amino acids while transporting amino groups as glutamic acid to the liver.
    • Deamination removes an amino group from amino acids as NH3, contributing to urea synthesis from liberated ammonia.

    Glutamate Dehydrogenase (GDH)

    • GDH, found in liver mitochondria, converts glutamate to α-ketoglutarate and ammonia.
    • GDH is regulated allosterically, activated by ADP and inhibited by GTP.

    Urea Cycle

    • Urea is synthesized in the liver and transported to kidneys for excretion, comprising two nitrogen atoms from ammonia and aspartic acid.
    • The urea cycle consists of five steps involving specific enzymes; initial steps occur in mitochondria while the latter steps take place in the cytosol.

    Enzyme Regulation and Deficiencies

    • Carbamoyl phosphate synthetase I (CPS I) initiates urea production by converting NH4+ and CO2 into carbamoyl phosphate, requiring N-acetylglutamate for activity.
    • Disorders of urea metabolism lead to hyperammonaemia, resulting from inherited or acquired enzyme deficiencies.

    Methionine Metabolism

    • Methionine is vital for epigenetic regulation and cysteine production, influencing gene expression through methylation processes.

    Phenylketonuria (PKU)

    • PKU is an autosomal recessive disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene, leading to mental retardation and other symptoms.
    • An early 20th-century case study identified the condition, originally named 'imbecillitas phenylpyruvica.'
    • Management involves a strict low-protein diet to mitigate symptoms and improve health outcomes.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Protein Metabolism PDF

    Description

    This quiz explores the processes involved in amino acid degradation, focusing on the production of ammonium and carbon skeletons. It covers their roles in synthesizing nitrogen-containing compounds and generating ATP, highlighting their importance in metabolism and energy production.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser