Transamination Reactions Quiz
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Questions and Answers

What happens to the blood sugar level when it is decreased to approximately half?

  • It decreases the heart rate.
  • It increases the body's metabolism.
  • It leads to coma due to lack of glucose in brain cells. (correct)
  • It causes excessive vomiting.

    • Where is most of the hypoglycin found in ackee fruit?

  • In the pulp
  • In the skin
  • In the stem
  • In the seed (correct)

    • What role do amino acids play in higher animals?

  • They serve as building blocks for proteins and precursors for various biomolecules. (correct)
  • They are only used for energy storage.
  • They have no significant function in animal metabolism.
  • They are primarily used as structural materials in bones.

    • What major fates do amino acids' carbon skeletons have when they are used as fuel?

    <p>Oxidation to CO2 via TCA</p> Signup and view all the answers

    How do vertebrates digest proteins for absorption?

    <p>Proteins are digested into amino acids or di- or tripeptides before absorption.</p> Signup and view all the answers

    What is the term used to refer to each unit of an amino acid sequence?

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

    How do amino acids serve as a source of energy when ingested in excess?

    <p>They undergo gluconeogenesis to form glucose.</p> Signup and view all the answers

    What happens when brain cells lack glucose?

    <p>Coma may occur</p> Signup and view all the answers

    What happens to a protein if the disulfide bridge linking the A-chain and B-chain of insulin is broken?

    <p>It becomes inactive</p> Signup and view all the answers

    Which amino acid is responsible for the formation of disulfide bonds in proteins?

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

    What is the structural difference between cysteine and cystine?

    <p>Presence of an extra CH2 group</p> Signup and view all the answers

    Which amino acid is known for its polarity due to the amide group?

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

    Which amino acid functions as a hydrogen bond donor?

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

    Which amino acid is negatively charged and referred to as aspartate when charged?

    <p>Aspartic Acid</p> Signup and view all the answers

    How many hydrophilic residues typically occur on the exterior surface of proteins?

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

    What is the function of the CO group in proteins?

    <p>H-bond acceptor</p> Signup and view all the answers

    What physiological symptoms do phenylketonurics experience?

    <p>Severe mental symptoms</p> Signup and view all the answers

    How does phenylketonuria affect tyrosine metabolism?

    <p>Inhibits tyrosine hydroxylation</p> Signup and view all the answers

    What skin-related condition is commonly observed in phenylketonurics?

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

    Why do phenylketonurics have lighter skin and hair colour compared to their siblings?

    <p>Impaired melanin synthesis</p> Signup and view all the answers

    What is the first step in the formation of melanin?

    <p>Tyrosine hydroxylation by tyrosinase</p> Signup and view all the answers

    What are the common CNS symptoms associated with phenylketonuria?

    <p>Hyperactivity and seizures</p> Signup and view all the answers

    What is the recommended therapy for phenylketonuria patients?

    <p>Low phenylalanine diet</p> Signup and view all the answers

    Why is early diagnosis crucial for phenylketonuria?

    <p>Prevent irreversible brain damage</p> Signup and view all the answers

    What is the major biochemical abnormality associated with Parkinson's Disease?

    <p>Degeneration of cells in the substania nigra and locus coelureus</p> Signup and view all the answers

    Which neurotransmitter is primarily affected in Parkinson's Disease?

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

    What happens to the release of dopamine as the number of surviving cells decreases in Parkinson's Disease?

    <p>It decreases</p> Signup and view all the answers

    Why is the administration of DOPA used in Parkinson's Disease treatment?

    <p>To relieve tremor symptoms temporarily</p> Signup and view all the answers

    What fate do ketogenic amino acids meet during degradation?

    <p>Converted into ketone bodies</p> Signup and view all the answers

    What distinguishes glucogenic amino acids from ketogenic amino acids in terms of degradation?

    <p>They can be converted to glucose</p> Signup and view all the answers

    What is the common fate of the carbon atoms from the degradation of amino acids?

    <p>Funneled into seven major metabolic intermediates</p> Signup and view all the answers

    What happens to dopamine levels when its concentration exceeds a certain threshold in Parkinson's Disease?

    <p>Dopamine becomes toxic</p> Signup and view all the answers

    What is the purpose of transamination?

    <p>To form glutamate by collecting amino groups</p> Signup and view all the answers

    Which enzyme is responsible for the formation of ammonia from glutamate?

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

    What is the prosthetic group of all transaminases?

    <p>Pyridoxal phosphate</p> Signup and view all the answers

    Where does oxidative deamination take place in the cell?

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

    What are the products of the reaction Glutamate + Oxaloacetate?

    <p>NH3 + alpha-ketoglutarate</p> Signup and view all the answers

    Why is it essential to convert NH4+ to urea in the liver?

    <p>To prevent NH4+ buildup in tissues</p> Signup and view all the answers

    Which amino acid reacts with alpha-ketoglutarate to form p-phenylpyruvate and glutamate?

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

    What is the nitrogen acceptor in the transamination reaction?

    <p>Alpha-ketoglutarate</p> Signup and view all the answers

    Study Notes

    Amino Acid Metabolism

    • Amino acids serve as building blocks of proteins and as precursors of many other important biomolecules such as hormones, purines, pyrimidines, porphyrins, and vitamins.
    • They also serve as a source of energy, particularly when they are ingested in excess.

    Digestion

    • Proteins cannot enter epithelial cells, and must be digested into amino acids or di-or tripeptides before absorption can occur.
    • Digestion involves several stages, including extraction of proteins from food, denaturation of proteins, and more.

    Transamination

    • Glutamate plays a crucial role in collecting amino groups from all over to form glutamate.
    • Transamination reactions involve the transfer of an amino group from an amino acid to a keto acid, resulting in a new amino acid and a keto acid.
    • Examples of transamination reactions include:
      • Glutamate + Oxaloacetate → α-KG + Aspartate
      • Ala + KG → Pyruvate + Glutamate
      • Asp + KG → OAA + Glutamate
      • Leu + KG → Ketoisocaproate + Glutamate
      • Tyrosine + KG → p-phenylpyruvate + Glutamate

    Oxidative Deamination

    • Glutamate is converted to α-KG and ammonia through oxidative deamination, catalyzed by glutamate dehydrogenase.
    • The enzyme responsible is GLUTAMATE DEHYDROGENASE, a mitochondrial enzyme.
    • The reaction involves the transfer of a hydride ion, with NAD+/NADP+ serving as a co-factor.

    Phenylketonuria (PKU)

    • PKU is a genetic disorder characterized by the inability to metabolize phenylalanine.
    • Symptoms include mental retardation, seizures, hyperactivity, and tremors.
    • The condition is diagnosed by testing urine with FeCl3, which gives a green olive color in the presence of phenylpyruvate.
    • Treatment involves a low-phenylalanine diet, which must be started at birth to avoid irreversible brain damage.

    Parkinson's Disease

    • Parkinson's disease is a neurodegenerative disorder characterized by the degeneration of cells in certain areas of the brain, leading to a deficiency of dopamine.
    • Symptoms include tremors, which can be relieved by administering DOPA.
    • The administration of DOPA is not a permanent cure, and the disease remains uncontrolled.

    Fates of Carbon Atoms of Degraded Amino Acids

    • The carbon skeletons of 20 amino acids are funneled into seven major metabolic intermediates, including pyruvate, acetyl-CoA, acetoacetyl-CoA, α-KG, succinyl-CoA, fumarate, and OAA.
    • Amino acids can be classified into ketogenic or glucogenic based on their fate.
    • Ketogenic amino acids are degraded into acetyl-CoA or acetoacetyl-CoA, while glucogenic amino acids are degraded into pyruvate, α-KG, succinyl-CoA, fumarate, or OAA.

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    Amino Acids - Lindo PHTH1011 003 PDF

    Description

    Test your knowledge on transamination reactions with this quiz. Learn about the conversion of amino acids to different compounds like ketoglutarate and glutamate. Explore how transamination helps in the synthesis of various important molecules.

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