Biochemistry EBA 1300: Proteins Lecture 6 Quiz
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Questions and Answers

What characterizes hydrophobic amino acids in terms of their interaction with water?

  • They form hydrogen bonds with water.
  • They are always charged.
  • They dissolve easily in water.
  • They tend to repel water. (correct)
  • Which of the following amino acids is considered positively charged and hydrophilic?

  • Cysteine
  • Lysine (correct)
  • Aspartic acid
  • Serine
  • Which type of amino acid has more carboxyl groups than amino groups?

  • Negatively charged amino acids (correct)
  • Uncharged amino acids
  • Essential amino acids
  • Hydrophobic amino acids
  • What is the primary role of essential amino acids in the diet?

    <p>They must be provided in the diet.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of polar amino acids?

    <p>They are predominantly non-polar.</p> Signup and view all the answers

    What distinguishes semi-essential amino acids from non-essential amino acids?

    <p>Semi-essential amino acids are not needed in children.</p> Signup and view all the answers

    Which group of amino acids is characterized by containing polar functional groups but being uncharged?

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

    Which of the following amino acids would be classified as a representative of the uncharged, polar amino acids?

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

    What are proteins primarily made of?

    <p>Amino acids</p> Signup and view all the answers

    Which process is required to link amino acids together to form a protein?

    <p>Dehydration synthesis</p> Signup and view all the answers

    What role do enzymes play in biological systems?

    <p>They act as catalysts and speed up chemical reactions</p> Signup and view all the answers

    Which of the following is NOT a role of proteins in the body?

    <p>Storing energy</p> Signup and view all the answers

    What are the two typical substituents on the α-carbon atom of amino acids?

    <p>Hydrogen atom and R group</p> Signup and view all the answers

    What is the basic structure of an amino acid?

    <p>An amino group, a carboxylic acid group, a hydrogen atom, and an R-group</p> Signup and view all the answers

    How are amino acids classified based on their R groups?

    <p>By their electrochemical and physiological properties</p> Signup and view all the answers

    Which classification represents amino acids that do not contain aromatic rings?

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

    Which property is NOT characteristic of amino acids?

    <p>Low melting and boiling points</p> Signup and view all the answers

    Which statement about hormones is true?

    <p>They often act to control or regulate specific physiological processes in the body</p> Signup and view all the answers

    Which type of R group characterizes aromatic amino acids?

    <p>It contains conjugated rings</p> Signup and view all the answers

    Which elements are major components of amino acids?

    <p>Carbon, hydrogen, nitrogen, oxygen</p> Signup and view all the answers

    Which amino acid classification includes those with R-groups that have NH2 > COOH?

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

    What type of amino acids would you classify those with a hydroxyl group present?

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

    What classification includes amino acids characterized by the R group being not benzene?

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

    What property differentiates the properties of amino acids and, consequently, proteins?

    <p>The nature of the R groups</p> Signup and view all the answers

    Study Notes

    Biochemistry Science: Course Code EBA 1300

    • Course code: EBA 1300

    Fundamental Biochemistry of Proteins (Lecture 6)

    • Lecture topic: Fundamental biochemistry of proteins
    • Lecture number: 6

    Table of Contents

    • Topic 1: Definition of proteins
    • Topic 2: Importance of proteins
    • Topic 3: Properties of amino acids
    • Topic 4: Classification of amino acids

    Proteins

    • Found in various foods (e.g., meat, seafood, cheese, nuts, legumes)
    • Fight infections
    • Help cells divide

    Definition of Protein

    • Biological macromolecules within living bodies
    • Macromolecules are large
    • Proteins are polymers
    • Polymers consist of monomers

    Protein Structure

    • Very large compared to sugar or salt molecules
    • Polymers composed of smaller units called amino acids
    • Contain carbon (C), hydrogen (H), oxygen (O), and nitrogen (N)

    Building a Protein

    • Requires dehydration synthesis - removal of water
    • Amino acids linked together by peptide bonds
    • Proteins = polypeptides

    Importance of Proteins

    • Found in animal and plant products (e.g., nuts, legumes)
    • Important large, complex molecules in the body
    • Essential for building muscle mass
    • Crucial for the structure, function, and regulation of body tissues and organs

    Proteins as Enzymes

    • Catalysts speeding up chemical reactions
    • Lower activation energy
    • Enzyme specificity to temperature and pH

    Proteins as Chemical Messengers (Hormones)

    • Chemical signaling molecules (often small proteins or steroids)
    • Secreted by endocrine cells
    • Regulate physiological processes, like growth, development, metabolism, and reproduction
    • Example: Insulin regulates blood glucose levels

    Amino Acids: Building Blocks of Protein

    • Monomers of proteins
    • Contain carbon (C), hydrogen (H), nitrogen (N), and oxygen (O)
    • Approximately 500 known amino acids, but 20 appear in the genetic code
    • Can be classified in various ways

    General Properties of Amino Acids

    • High melting and boiling points
    • White crystalline solid substances
    • Some are sweet, tasteless, or bitter
    • Mostly soluble in water, insoluble in organic solvents

    Amino Acid Structure

    • Central carbon atom (α-carbon)
    • Amino group (-NH2)
    • Carboxyl group (-COOH)
    • Hydrogen atom
    • Unique side chain (R-group)

    Amino Acid Classification

    • Differ in specific chemical properties and structure of their R-groups
    • Nature of the R-group determines protein properties
    • Classification based on R-group properties: electrochemical polarity, physiological classification, structural classification, metabolic classification

    Structural Classification of Amino Acids

    • Aliphatic (no ring):
      • Neutral
      • Acidic
      • Basic
    • Aromatic (containing a benzene ring)
    • Heterocyclic (R-group not benzene)

    Aliphatic (Neutral)

    • Branched
      • Valine (Val, V)
      • Leucine (Leu, L)
      • Isoleucine (Ile, I)
    • Unbranched
      • Glycine (Gly, G)
      • Alanine (Ala, A)
      • Hydroxyl-containing
        • Serine (Ser, S)
        • Threonine (Thr, T)
      • Sulfur-containing
        • Cysteine (Cys, C)
        • Methionine (Met, M)
      • Aliphatic (Acidic)
    • Aspartic acid (Asp, D)
    • Glutamic acid (Glu, E)
      • Amides
        • Asparagine (Asn, N)
        • Glutamine (Gln, Q)
    • Aliphatic (Basic)
      • Lysine (Lys, K)
      • Arginine (Arg, R)
      • Histidine (His, H)

    Aromatic Amino Acids

    • Phenylalanine (Phe, F)
    • Tyrosine (Tyr, Y)
    • Tryptophan (Trp, W)
      • Have conjugated rings
      • Characteristic smells (bananas, oranges)

    Heterocyclic Amino Acids

    • Proline (Pro, P)
    • Histidine (His, H)
      • R-groups not benzene rings

    Electrochemical Classification

    • Hydrophobic (nonpolar):
      • Repel aqueous environment
      • Primarily in protein interiors
      • Do not participate in hydrogen bonding
    • Hydrophilic (polar): (including charged amino acids), which interact well with water or participate in hydrogen bonding

    Nonpolar or Hydrophobic Amino Acids

    • List of amino acids

    Polar or Hydrophilic Amino Acids

    • Positively charged (Basic)
      • Arginine, Histidine, Lysine
    • Negatively charged (Acidic)
      • Aspartic and Glutamic Acid
    • Polar uncharged
      • Serine, Threonine, Cysteine, Asparagine, Glutamine

    Biological or Physiological Classification

    • Essential
      • Cannot be synthesized by the body. Must be obtained from the diet.
    • Semi-essential
      • Can be synthesized by the body, but not in sufficient amounts for adults (but enough for children) Arginine Histidine
    • Nonessential
      • Can be synthesized by the body in sufficient amounts.

    Amino Acid Three-Letter Codes

    • Table of amino acids and their three-letter codes

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    Protein and Amino Acid 06 PDF

    Description

    Test your knowledge on the fundamental biochemistry of proteins in the EBA 1300 course. This quiz covers the definitions, importance, properties, and classification of proteins and amino acids. Dive into the basics of protein structures and their biological significance.

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