Amino Acids and Their Functions
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Questions and Answers

How many amino acids have been found in nature that are directly involved in the structure of body proteins?

  • 12
  • 20 (correct)
  • 50
  • 100

    • What is the function of L α-amino acids in the context of protein synthesis?

  • They are essential for the formation of body proteins. (correct)
  • They serve as inhibitors in metabolic reactions.
  • They no longer play a role in protein structure.
  • They are involved exclusively in energy production.

    • What distinguishes D-amino acids from L-amino acids in biological systems?

  • D-amino acids are present in some organisms but not involved in body proteins. (correct)
  • D-amino acids are the primary source of energy.
  • D-amino acids are utilized in protein synthesis.
  • D-amino acids are always harmful to organisms.

    • What are amino acids primarily considered in the context of proteins?

    <p>Basic building units of proteins.</p> Signup and view all the answers

    Which of the following is NOT a recognized function of amino acids?

    <p>Source of immediate energy without any byproducts.</p> Signup and view all the answers

    What is meant by the term 'amphoteric properties' in relation to amino acids?

    <p>Amino acids can act as both acids and bases.</p> Signup and view all the answers

    Which of the following groups best represents the nutritional classification of amino acids?

    <p>Essential and non-essential.</p> Signup and view all the answers

    In the context of the general structure of amino acids, what does R represent in the amino acid structure?

    <p>The variable side chain that defines each amino acid.</p> Signup and view all the answers

    Which amino acid is classified as nonessential and can be synthesized by the human body?

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

    Which amino acid contains an indole ring structure?

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

    What is the primary reason essential amino acids are vital for human health?

    <p>They must be obtained from food because the body cannot synthesize them.</p> Signup and view all the answers

    Which of the following amino acids is considered ketogenic?

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

    Which of these proteins is considered to have a high biological value?

    <p>Egg protein</p> Signup and view all the answers

    What classification applies to amino acids that can give rise to glucose?

    <p>Glucogenic amino acids</p> Signup and view all the answers

    Which of the following amino acids is not classified as a heterocyclic amino acid?

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

    Which amino acid is known to contain a pyrrolidine ring structure?

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

    Which of the following amino acids belongs to the aliphatic category?

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

    Identify the amino acid that contains a sulfur atom.

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

    Which of the following amino acids is classified as a basic amino acid?

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

    Which amino acid listed is an aromatic amino acid containing a benzene ring?

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

    What is the structure type of aspartic acid?

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

    Which of the following is NOT a characteristic of branched-chain amino acids?

    <p>They have a linear structure</p> Signup and view all the answers

    What type of amino acid is proline categorized under?

    <p>Heterocyclic amino acid</p> Signup and view all the answers

    Which amino acid is primarily known for its role in the formation of disulfide bonds?

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

    Which amino acids are exclusively ketogenic?

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

    Which of the following amino acids can be classified as both glucogenic and ketogenic?

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

    At the isoelectric point, the amino group of an amino acid gains which type of charge?

    <p>Positive charge</p> Signup and view all the answers

    Which property allows amino acids to act as both acids and bases?

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

    What is the ion form called when an amino acid is at its isoelectric point?

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

    Which of the following is NOT a glucogenic amino acid?

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

    Which amino acids are primarily glucogenic?

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

    What occurs to the carboxyl group of an amino acid at its isoelectric point?

    <p>It loses a hydrogen atom</p> Signup and view all the answers

    Study Notes

    Introduction

    • There are hundreds of amino acids in nature.
    • 20 amino acids are essential for the structure of the human body.
    • These 20 amino acids have genetic codes on DNA.

    Structure

    • An amino acid is an organic acid, where one hydrogen atom is replaced by an amino group (NH2).
    • The amino group is attached to the α-carbon atom.

    Isomerism

    • Most amino acids can exist in two optical isomers: D or L.
    • Only L α-amino acids are used in the formation of body proteins.
    • D-amino acids are found in some organisms and plants.

    Functions

    • Amino acids are the basic building blocks of proteins.
    • They are a source of energy.
    • They are used to synthesize other molecules, for example, Glycine forms 33% of collagen protein.

    Classification by Structure

    • Aliphatic amino acids have no ring structure.
      • Neutral: Glycine, Alanine.
      • Branched chain: Valine, Leucine, Isoleucine.
      • Hydroxy-containing: Serine, Threonine, Tyrosine.
      • Sulfur-containing: Cysteine, Methionine.
      • Acidic: Aspartic acid, Glutamic acid.
      • Basic: Arginine, Lysine.
    • Aromatic amino acids contain an aromatic ring.
      • Phenylalanine.
      • Tyrosine.
    • Heterocyclic amino acids have a ring structure containing atoms other than carbons.
      • Tryptophan.
      • Histidine.
      • Proline.

    Nutritional Classification

    • Essential amino acids cannot be synthesized by the human body and must be obtained from food.
    • Nonessential amino acids can be synthesized by the body.
    • Proteins containing all essential amino acids are of high biological value.
    • Proteins deficient in one or more essential amino acids are of low biological value.

    Metabolic Fate

    • Glucogenic amino acids can be converted to glucose.
    • Ketogenic amino acids can be converted to ketone bodies.
    • Glucogenic and ketogenic amino acids can be converted to both glucose and ketone bodies.
    • Leucine and lysine are the only ketogenic amino acids.
    • Isoleucine, tryptophan, tyrosine, and phenylalanine are the only glucogenic and ketogenic amino acids.
    • The rest are glucogenic.

    Amphoteric Properties

    • Amino acids are amphoteric, meaning they can act as both acids and bases.
    • The isoelectric point is the pH at which the amino acid has a net charge of zero.
    • At the isoelectric point, the amino group gains a positive charge (is protonated) and the acid group gains a negative charge (is deprotonated).
    • This ion is called a zwitterion.

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    Amino Acids Chemistry PDF

    Description

    This quiz covers the structure, classification, and functions of amino acids, focusing on their role in the human body. It includes details about essential amino acids, isomerism, and their significance in protein synthesis and energy production.

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