Biochemistry: Peptides and Amino Acids Quiz
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Questions and Answers

What is the maximum number of amino acids that can be present in a peptide?

  • 100 amino acids
  • Less than 50 amino acids (correct)
  • 10 amino acids
  • 50 amino acids

    • Which term refers to a peptide composed specifically of three amino acids?

  • Polypeptide
  • Oligopeptide
  • Dipeptide
  • Tripeptide (correct)

    • What type of bond joins the amino acids in a peptide?

  • Hydrogen bond
  • Ionic bond
  • Peptide bond (correct)
  • Disulfide bond

    • Which of the following is TRUE concerning polypeptides?

    <p>Polypeptides are chains of more than 50 amino acids.</p> Signup and view all the answers

    What is the sequence of amino acids in a peptide primarily responsible for?

    <p>Defining the peptide's biological function</p> Signup and view all the answers

    How many amino acids are present in a tetrapeptide?

    <p>4</p> Signup and view all the answers

    What is an oligopeptide?

    <p>A peptide consisting of a few amino acids</p> Signup and view all the answers

    What is one of the mechanisms through which lactoferricins exert their antibacterial action?

    <p>Disruption of normal membrane permeability</p> Signup and view all the answers

    Which amino acid addition can enhance the antioxidant activity of peptides derived from milk proteins?

    <p>Leucine or proline at the N-terminus</p> Signup and view all the answers

    Which of the following statements about bioactive peptides is true?

    <p>Some peptides can exhibit multiple beneficial effects.</p> Signup and view all the answers

    What role do microbial fermentation processes play in the production of bioactive peptides?

    <p>Fermentation helps release peptides from host proteins in dairy.</p> Signup and view all the answers

    Why have peptides gained importance in molecular biology recently?

    <p>They allow for the development of peptide antibodies without protein purification.</p> Signup and view all the answers

    What is the minimum number of amino acids required to form a polypeptide?

    <p>50</p> Signup and view all the answers

    Which of the following peptide types contains the largest number of amino acids?

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

    What type of bond is formed between amino acids to create peptides?

    <p>Peptide bond</p> Signup and view all the answers

    Which peptide is an example of a nonapeptide?

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

    What is the role of Substance P in the body?

    <p>Pain mediator</p> Signup and view all the answers

    The formation of a peptide bond includes the release of which molecule?

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

    Which peptide is directly associated with childbirth?

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

    What type of compounds are polymyxin B and bacitracin classified as?

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

    Which compound primarily serves as a toxin derived from mushrooms?

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

    What specifically can break peptide bonds in proteins?

    <p>Prolonged exposure to strong acid or base</p> Signup and view all the answers

    Which of the following is NOT a characteristic of peptide bonds?

    <p>Flexible and allows free rotation</p> Signup and view all the answers

    What is a key function of glutathione in the body?

    <p>Regenerates itself and reduces free radicals</p> Signup and view all the answers

    Which of the following peptides is modified to form a different compound?

    <p>Thyrotropin releasing hormone (TRH)</p> Signup and view all the answers

    What effect does increasing glutathione levels have on physical performance?

    <p>Decreases muscle damage</p> Signup and view all the answers

    Which of the following peptides is known to cause hypertension?

    <p>Angiotensin I</p> Signup and view all the answers

    Which amino acid is mentioned as the master antioxidant's component?

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

    What stabilizes the structure of proteins through peptide bonds?

    <p>Hydrogen bonds in different peptide parts</p> Signup and view all the answers

    Which peptide is classified as a nanopeptide?

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

    Which amino acid forms part of the structure of glutathione?

    <p>Glutamic acid</p> Signup and view all the answers

    What is the primary action of nisin against microorganisms?

    <p>Acts on the cytoplasmic membrane</p> Signup and view all the answers

    Which characteristic allows nisin to function effectively in food preservation?

    <p>Presence of multiple thioether bridges</p> Signup and view all the answers

    What types of microorganisms is nisin particularly effective against?

    <p>Gram-positive microorganisms</p> Signup and view all the answers

    Which health benefits are associated with food-derived peptides?

    <p>Cholesterol-lowering ability</p> Signup and view all the answers

    Which unusual amino acid is NOT part of nisin's structure?

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

    What effect do food-derived peptides have on mineral absorption?

    <p>They enhance mineral absorption</p> Signup and view all the answers

    Which of the following statements regarding nisin's use is true?

    <p>It is permitted as a preservative in several countries.</p> Signup and view all the answers

    Which peptides contain a β-amino acid bound to histidine?

    <p>Carnosine, anserine, and balenine</p> Signup and view all the answers

    How do peptides derived from food affect blood pressure?

    <p>They can lower blood pressure.</p> Signup and view all the answers

    What is a notable application of nisin in food processing?

    <p>Suppressing anaerobes in cheese products</p> Signup and view all the answers

    Study Notes

    Peptides, Polypeptides & Biochemical Importance

    • Peptides are formed when fewer than 50 amino acids join via a peptide bond.
    • Alternatively, peptides are short polymers of amino acids; usually monomers linked by peptide bonds. These covalent chemical bonds form between two molecules when the carboxyl group of one molecule reacts with the amino group of another molecule.
    • Polypeptides are peptides with more than 10 amino acid residues.
    • Peptides' structure and function depend upon the nature of amino acids present, their sequence, and spatial relationship.
    • Many peptides stem from the breakdown of proteins. Peptides are relatively small polymers (2-10 amino acids). If 2 amino acids are involved, it's a dipeptide; 3 is a tripeptide, and 10 is a decapeptide. Oligopeptides contain a few amino acids. Polypeptides are larger peptides; containing more than 50 amino acids.

    Types of Peptides

    • The shortest peptide is a dipeptide, made of two amino acids joined by a peptide bond, to form a dipeptide molecule.
    • Tripeptides
    • Tetrapeptides and so on...

    Proteins

    • Proteins are chains of amino acids.
    • Short chains of amino acids are called peptides.
    • Peptides of more than 10 amino acid residues are called polypeptides.

    Peptide/Polypeptides

    • Peptides are polymers of amino acids.
    • Their structure and functions depend upon the nature of amino acids, sequence and spatial relationship among them.

    Peptide Bond Formation

    • Amino acids attach covalently via a carboxyl group on one side and an amino group on the other side.
    • This forms an amide bond (called a peptide bond).
    • Peptide bond formation is a condensation reaction. A water molecule is removed when two amino acids link.

    Characteristics of Peptide Bonds

    • Peptide bonds are strong, possessing partial double bond character.
    • They are typically not broken by common denaturing agents (e.g., heat or high salt concentrations).
    • Strong acids or bases at elevated temperatures or specific enzymes (such as digestive enzymes) can break them.
    • Peptide bonds are rigid and planar, resisting free rotation. This rigidity stabilizes protein structure.
    • Peptide bonds are uncharged but polar. Polar hydrogen atoms of amino groups and polar oxygen atoms of carboxyl groups contribute to this polarity.
    • This polarity allows hydrogen bonds to form between peptide bonds in different parts of the chain.

    Individual Peptides

    • Peptides are widespread in nature.
    • They are often involved in specific biological activities such as peptide hormones, peptide toxins, and peptide antibiotics.
    • Examples include:
      • Thyrotropin-releasing hormone (TRH): a tripeptide.
      • Glu-His-Pro is its sequence; Glu is modified to form pyroglutamic acid.
      • Oxytocin and Vasopressin (ADH): nanopeptides (9 amino acids). Secretion from posterior pituitary.
      • Angiotensin I (10 amino acids) and Angiotensin II (8 amino acids) cause hypertension.
      • Glutathione (L-glutamyl-L-cysteinyl-glycine). Widespread in animals, plants, and microorganisms
      • Cysteine, glycine, and glutamine: Produced naturally in the body. Master antioxidant. Itself regenerates in the liver. Crucial for muscle damage recovery, strength/endurance, shifts from fat metabolism to muscle development and immune system health.
      • 2-Lysine Peptides: As effective as lysine in rat growth and feeding trials.
      • 3-Nisin: Formed by several strains of Streptococcus lactis to combat gram-positive microorganisms (lactic acid bacteria, Streptococci, Bacilli, Clostridia).
      • 4- Carnosine, Anserine, and Balenine: Peptides containing a β-amino acid (β-alanine) bound to L-histidine or a derivative. Found in meat extract.

    Types of Bio-Active Peptides

    • Antimicrobial peptides
    • Antioxidant peptides

    Food Applications of Bioactive Peptides

    • Many peptides occur naturally in foods.
    • Some are released during food fermentation (e.g., cheese ripening).
    • Enzymes in the gut can create peptides from proteins in food.

    Peptides in Molecular Biology

    • Peptides have become essential in molecular biology.
    • They permit the creation of peptide antibodies in animals without purifying the protein of interest.
    • Peptides are also used in mass spectrometry to identify proteins based on mass and sequence.

    C-Peptide

    • Patients with diabetes may have their C-peptide levels measured to distinguish type 1 from type 2 diabetes.
    • C-peptide levels may also assist in diagnosing hypoglycemia.
    • C-peptide levels can be checked in PCOS patients to assess insulin resistance.
    • C-peptide can also be used to identify gastrinomas associated with multiple endocrine neoplasm syndromes.

    Peptide/Chemical Applications

    • Antimicrobial peptides have been used as therapeutic agents. (e.g., Bacitracin, Boceprevir, Dalbavancin, Daptomycin, Enfuvirtide, Oritavancin, Teicoplanin, Telaprevir, Telavancin, Vancomycin, and Guavanin).
    • Benefits of collagen peptides (therapeutic). Includes improving joint/bone health and aiding aging/skin beauty/connective tissue health.
    • Brain Peptides: Receptors that bind opiates like morphine; called endorphins (endogenous morphine). Dynorphin is a significant peptide (13 amino acids) due to its potency (superopioate).
    • The term peptide can refer to secretogue peptides or peptide hormones in sports doping.
    • This class includes substances that cause other substances to release.
    • Proteins can be classified functionally; including enzyme/protease which breaks down proteins; defence functions such as antibodies fighting viruses; contracts, transportation, regulation, and support functions.

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    Peptides, Polypeptides & Biochemical Importance PDF

    Description

    Test your knowledge on the structure, function, and characteristics of peptides and amino acids. This quiz covers key concepts such as the types of peptides, amino acid bonding, and the biological significance of peptides. Perfect for students studying biochemistry or molecular biology.

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