Introduction to Amino Acids
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Questions and Answers

What property of the amino acid is primarily determined by the 'R' group?

  • Color in solution
  • Molecular weight
  • Melting point
  • Solubility in water (correct)
  • Which of the following amino acids is classified as a branched-chain amino acid (BCAA)?

  • Isoleucine (correct)
  • Arginine
  • Serine
  • Lysine
  • In terms of polarity, which amino acid is classified as non-polar?

  • Isoleucine (correct)
  • Serine
  • Threonine
  • Glycine
  • Which classification of amino acids is based on their metabolic fate?

    <p>Gluconeogenic and ketogenic</p> Signup and view all the answers

    Where are hydrophobic (non-polar) amino acids typically located within a protein structure?

    <p>In the interior of the molecule</p> Signup and view all the answers

    Which of the following amino acids is considered basic?

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

    What type of side chain does aspartate possess?

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

    Which of the following amino acids is involved in maple syrup urine disease due to abnormal metabolism?

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

    Which property of amino acids describes their ability to act as both acids and bases?

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

    What configuration do all amino acids of physiological significance in the human body possess?

    <p>L-α configuration</p> Signup and view all the answers

    What is the pH at which an amino acid is in its zwitterionic form?

    <p>Isoelectric pH</p> Signup and view all the answers

    Which of the following amino acids is considered non-chiral?

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

    Which classification does NOT describe amino acids?

    <p>Non-proteinogenic amino acids</p> Signup and view all the answers

    What is the main characteristic of the 20 proteinogenic amino acids?

    <p>They are involved in protein synthesis.</p> Signup and view all the answers

    What happens to amino acids in an acidic solution?

    <p>They become positively charged.</p> Signup and view all the answers

    How many naturally occurring amino acids are there?

    <p>300</p> Signup and view all the answers

    What results from the substitution of glutamate by valine in hemoglobin?

    <p>Sickle cell anemia</p> Signup and view all the answers

    What characterizes a Zwitterion?

    <p>It is electrically neutral overall.</p> Signup and view all the answers

    Which amino acid can form disulfide bonds to stabilize protein structure?

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

    What is the effect of amino acids at their isoelectric point (pI)?

    <p>They clump together and precipitate out of the solution.</p> Signup and view all the answers

    Which process is associated with the Golgi bodies?

    <p>O-linked glycosylation</p> Signup and view all the answers

    Which amino acid is likely to have a higher isoelectric point?

    <p>Arginine with pH 10.8</p> Signup and view all the answers

    When does positive nitrogen balance occur?

    <p>During growth</p> Signup and view all the answers

    What is the main condition when nitrogen intake equals nitrogen excretion?

    <p>Nitrogen equilibrium</p> Signup and view all the answers

    Which of the following has maximum buffering capacity?

    <p>Histidine due to its imidazole group.</p> Signup and view all the answers

    At what pH range do amino acids with hydrocarbon R groups typically attain their isoelectric points?

    <p>pH 5.0 to 7.0</p> Signup and view all the answers

    Which amino acids are considered semi-essential and required during positive nitrogen balance?

    <p>Arginine and Histidine</p> Signup and view all the answers

    What can destroy disulfide bonds and denature proteins?

    <p>Chemical reduction</p> Signup and view all the answers

    Why are proteins considered one of the major buffering systems in the body?

    <p>They can neutralize small increases of acid or base.</p> Signup and view all the answers

    Which statement about acidic amino acids is true?

    <p>They need low pH values to reach their isoelectric points.</p> Signup and view all the answers

    What is an example of a condition leading to negative nitrogen balance?

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

    What happens to proteins at their isoelectric point?

    <p>They precipitate out of the solution.</p> Signup and view all the answers

    Which amino acid serves as a precursor for the production of nitric oxide?

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

    Which amino acid is classified as non-polar?

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

    Which of the following amino acids is a derivative of Tryptophan?

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

    What is the status of proteins that are low in one or more essential amino acids?

    <p>Incomplete Proteins</p> Signup and view all the answers

    Which amino acid is directly involved in the synthesis of GABA?

    <p>L-Glutamate</p> Signup and view all the answers

    Study Notes

    Introduction to Amino Acids

    • Organisms, including humans, are primarily composed of four basic biomolecules: carbohydrates, proteins, lipids, and nucleic acids.
    • The study of amino acids covers their structure, properties, classification, nitrogen balance, and derivatives.

    Basic Characteristics of Amino Acids

    • Over 300 naturally occurring amino acids identified, with 20 being proteinogenic.
    • Amino acids are crucial for bodily functions, including nerve transmission and hormone synthesis.
    • Physiologically significant amino acids possess L-α configuration.

    Structural Properties

    • All amino acids are chiral except Glycine, which is symmetrical.
    • Amphoteric properties allow amino acids to act as acids or bases depending on the pH of the solution.
    • At low pH, they accept protons (positively charged); at high pH, they donate protons (negatively charged).

    Isoelectric Point (pI)

    • A Zwitterion forms when an amino acid has equal positive and negative charges, existing at its unique isoelectric point.
    • pI varies among amino acids:
      • Hydrocarbon R groups: pH 5.0-7.0 (e.g., Leucine pH 6.0)
      • Basic amino acids: require high pH (e.g., Arginine pH 10.8)
      • Acidic amino acids: require low pH (e.g., Aspartic acid pH 3.0).

    Classification of Amino Acids

    • Classified based on R group properties, determining hydrophobicity, polarity, and charge.
    • Categories include:
      • Non-polar (e.g., Glycine, Alanine, Valine)
      • Polar and charged (e.g., Histidine, Aspartate)
      • Essential (e.g., Phenylalanine, Valine, Threonine) and non-essential amino acids.

    Nitrogen Balance

    • Normal nitrogen balance occurs when nitrogen intake equals excretion.
    • Negative nitrogen balance: Intake < excretion; caused by malnutrition, starvation, or infections.
    • Positive nitrogen balance: Intake > excretion; linked to growth, pregnancy, or recovery from illness.

    Amino Acid Derivatives

    • Key derivatives include:
      • Tryptophan transforms into Serotonin, Melatonin, and Niacin.
      • Tyrosine converts into Dopamine, Norepinephrine, and Epinephrine.
      • Histidine is the precursor for Histamine.
    • Arginine is a precursor for Nitric Oxide; Ornithine is transformed into Spermine; GABA is synthesized from L-glutamate.

    Additional Notes

    • Hydrophobic amino acids (e.g., Valine, Leucine) tend to be located in the core of proteins, while hydrophilic amino acids reside on the surface.
    • Unique characteristics, like the branched-chain nature of certain amino acids, affect metabolism and can lead to conditions like Maple Syrup Urine Disease or Sickle Cell Anemia.
    • Glycosylation in proteins occurs at specific amino acids (Serine, Threonine for O-linked; Asparagine for N-linked).

    Fun Fact

    • Selenocysteine is recognized as the 21st amino acid.

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    Description

    Dive into the fascinating world of amino acids, the building blocks of proteins. This quiz explores their structure, properties, classification, and key roles in biological processes. Learn about the unique characteristics that make amino acids essential for life.

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