Biochemistry: Amino Acids and Proteins Quiz
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Questions and Answers

How many standard proteinogenic amino acids are there?

  • 20 (correct)
  • 24
  • 22
  • 18

    • What is the primary biochemical designation of an amino acid?

  • α-carbon (correct)
  • β-carbon
  • γ-carbon
  • R-group

    • Which amino acid does not possess an asymmetric carbon?

  • Valine
  • Serine
  • Alanine
  • Glycine (correct)

    • What configuration is typically found in natural amino acids?

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

    What term describes amino acids in ionized form at physiological pH?

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

    Which type of amino acids are characterized by their ability to act as both acids and bases?

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

    What is the total number of essential amino acids?

    <p>9</p> Signup and view all the answers

    Which of the following classifications is NOT used for amino acids?

    <p>Hydrophilic vs. Hydrophobic</p> Signup and view all the answers

    What structural changes occur during protein denaturation?

    <p>Loss of secondary, tertiary, and quaternary structure</p> Signup and view all the answers

    Which of the following proteins is classified as a globular protein?

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

    Which of the following can cause protein denaturation?

    <p>High pH environments</p> Signup and view all the answers

    What type of protein is hemoglobin classified as based on its composition?

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

    At what temperature does protein denaturation begin to occur?

    <p>41°C</p> Signup and view all the answers

    What is the primary role of insulin?

    <p>Lower blood glucose levels</p> Signup and view all the answers

    Which level of protein structure is characterized by hydrogen bonds?

    <p>Secondary structure</p> Signup and view all the answers

    Which example is classified as a fibrous protein?

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

    What defines the tertiary structure of a protein?

    <p>The three-dimensional folding of the protein</p> Signup and view all the answers

    What role do proline and glycine play in protein structure?

    <p>Inducing changes in direction of the peptide chain</p> Signup and view all the answers

    How many amino acids does insulin consist of?

    <p>51</p> Signup and view all the answers

    Which statement best describes the quaternary structure of proteins?

    <p>It consists of multiple subunits interacting</p> Signup and view all the answers

    Which is NOT a biological role of proteins?

    <p>Energy production</p> Signup and view all the answers

    Which amino acid is known for not having an asymmetric carbon?

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

    What is the product of the decarboxylation of histidine?

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

    Which amino acid transformation is associated with increased muscle tone when absent?

    <p>Aspartic acid to Asparagine</p> Signup and view all the answers

    Which process contributes to the formation of urea in the body?

    <p>Oxidative deamination</p> Signup and view all the answers

    How many amino acids classify a polypeptide?

    <p>10 to 100</p> Signup and view all the answers

    What is NOT a biological role of amino acids?

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

    Which post-translation modification involves the addition of sugar moieties to amino acids?

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

    What is the orientation of a peptide bond?

    <p>N-terminal to C-terminal</p> Signup and view all the answers

    Which classification of amino acids refers to their ability to be essential for human life?

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

    What characterizes polar amino acids as opposed to non-polar amino acids?

    <p>They are hydrophilic and can be ionized</p> Signup and view all the answers

    Which side chain type is associated with amino acids that can absorb UV light?

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

    How are amino acids classified based on their side chain structure?

    <p>Side chain nature</p> Signup and view all the answers

    What type of amino acid possesses a side chain that contains an acid group?

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

    What distinguishes non-proteinogenic amino acids from proteinogenic amino acids?

    <p>They lack essential roles in protein synthesis</p> Signup and view all the answers

    Which of the following correctly defines a property of non-polar amino acids?

    <p>They do not interact well with water</p> Signup and view all the answers

    Which classification system indicates the orientation of amino acids based on molecular configuration?

    <p>D/L form</p> Signup and view all the answers

    What is a defining characteristic of a peptide bond?

    <p>It is a covalent bond that connects the amino group of one amino acid to the carboxyl group of another.</p> Signup and view all the answers

    Which of the following correctly classifies amino acids?

    <p>Amino acids can be classified by their side chains as polar, nonpolar, acidic, or basic.</p> Signup and view all the answers

    What distinguishes D and L forms of amino acids?

    <p>The spatial arrangement of their atoms around the alpha carbon.</p> Signup and view all the answers

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

    <p>Providing energy through glycosidic bonds.</p> Signup and view all the answers

    How many proteinogenic amino acids are there?

    <p>22</p> Signup and view all the answers

    What are the four levels of protein structure?

    <p>Primary, secondary, tertiary, and quaternary.</p> Signup and view all the answers

    Which of the following organic molecules is NOT classified under the category of amino acids, peptides, and proteins?

    <p>Fatty acids.</p> Signup and view all the answers

    What is biochemistry primarily concerned with?

    <p>The integration of biology and chemistry to study biomolecules.</p> Signup and view all the answers

    Study Notes

    Amino Acids, Peptides, and Proteins

    • Amino Acids: About 500 amino acids exist naturally, organic molecules.
    • Proteinogenic Amino Acids: Are 22 in number, 20 standard and 2 non-standard.
    • Non-proteinogenic Amino Acids: Not incorporated into proteins
    • Essential Amino Acids: There are 9 essential amino acids.
    • Amino Acid Structure: Have an amino group, carboxyl group, an alpha carbon, and a side chain (R group).
    • Asymmetric Carbon: Most amino acids have a chiral center that is bonded to four different groups. Glycine is the only one that lacks an asymmetric carbon.
    • Chirality: Amino acids exhibit chirality with L and D forms. Natural amino acids are L-configured.
    • Amino Acids Classification:
      • Proteinogenic/non-proteinogenic
      • Standard/non-standard
      • Essential/non-essential
      • Polar/non-polar
      • side chain structure/ nature
      • Acid/base group

    Peptide and Protein

    • Amino Acid: A single unit of an amino acid, monomer, or residue.
    • Peptides: Chains of more than 2 amino acids;
      • Oligopeptide: 2 to 10 amino acids
      • Polypeptide: 10 to 100 amino acids
    • Protein: Over 100 amino acids.
    • Peptide Bond: Connects amino acids. Formed through a dehydration reaction removing water.
    • Peptide Bond Properties:
      • N-terminal and C-terminal ends
      • Strong (partial double bond character)
      • Stable and planar structure
      • Lack of rotation

    Peptide Examples

    • Glutathione (antioxidant): Cys-Glu-Gly, involved in cellular redox reactions.
    • Insulin (hormone): 51 amino acids, from pancreatic beta cells regulating blood glucose levels.

    Protein Synthesis

    • Translation: Protein synthesis process using mRNA instructions.

    Protein Biological Roles

    • Structural: Form building blocks of tissues and organs.
    • Metabolic and functional: Participate in various metabolic processes, including energy production and cell signaling.
    • Energetic: Supply energy to cells when needed.
    • Transport: Carry substances throughout the body.
    • Defense: Protect the body from pathogens and foreign substances.
    • Enzymatic: Act as catalysts in biochemical reactions.
    • Storage: Store nutrients for later use.

    Protein Levels of Structure

    • Primary: Amino acid sequence.
    • Secondary: Hydrogen bonding (alpha helix, beta sheet).
    • Tertiary: 3D structure of a single protein.
    • Quaternary: Multiple protein subunits, their interactions.

    Protein Classification

    • Shape:
      • Fibrous Example: Keratin, collagen
      • Globular Example: Hemoglobin
    • Composition:
      • Simple Example: Albumin, globulins
      • Conjugated: protein + non-protein part Example: glycoproteins, lipoproteins, nucleoproteins, metalloproteins.

    Protein Denaturation

    • Loss of Structure and Function:
      • Chemical and Physical Agents cause loss of secondary, tertiary, and quaternary structure. Chemical agents: temperature, pH, solvents, and heavy metal ions. Physical agents: agitation.
    • Examples:
      • Cooking eggs, hair care, damaged protein due to fever.

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    Amino acids, Peptides and Proteins - Chapter 1 - 2024-2025 PDF

    Description

    Test your knowledge of amino acids and proteins in this comprehensive quiz. Explore topics such as protein structure, denaturation, and the roles of essential amino acids. Perfect for students studying biochemistry or related fields.

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