Proteins: Structure and Functions
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Questions and Answers

What is the primary building block of proteins?

  • Amino acids (correct)
  • Nucleotides
  • Monosaccharides
  • Fatty acids
  • What percentage of body composition does protein typically represent in adults?

  • 30-35%
  • 12-18% (correct)
  • 20-25%
  • 5-10%
  • Which amino acid classification is associated with a negatively charged group?

  • Acidic amino acids (correct)
  • Neutral nonpolar amino acids
  • Essential amino acids
  • Basic amino acids
  • How many different types of amino acids are recognized as common in protein synthesis?

    <p>20 (B)</p> Signup and view all the answers

    What type of bond connects amino acids to form proteins?

    <p>Covalent bond (A)</p> Signup and view all the answers

    Which of the following describes a polypeptide?

    <p>A chain of 10 to 2000 or more amino acids (A)</p> Signup and view all the answers

    What characterizes the primary structure of a protein?

    <p>The sequence of amino acids (B)</p> Signup and view all the answers

    Which type of amino acid is hydrophobic and interacts poorly with water?

    <p>Neutral nonpolar amino acids (A)</p> Signup and view all the answers

    Flashcards

    Protein

    Large macromolecules made of amino acids.

    Amino acids

    Monomers that form proteins; 20 types exist.

    Peptide bond

    Covalent bond joining amino acids in proteins.

    Dipeptide

    A molecule formed by 2 amino acids.

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    Polypeptide

    Chain of 10 or more amino acids.

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    Hydrophobic amino acids

    Neutral non-polar amino acids that interact poorly with water.

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    Primary structure

    Linear sequence of amino acids in a polypeptide.

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    Essential amino acids

    10 amino acids that must be obtained from diet.

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    Study Notes

    Protein Structure

    • Proteins are large macromolecules made of carbon, hydrogen, oxygen, and nitrogen, and sometimes sulfur.
    • Adult human bodies contain 12-18% protein by weight.
    • Proteins have four levels of structural organization.

    Protein Functions

    • Proteins form the structural framework of tissues like bone and connective tissue.
    • They act as enzymes, catalyzing biochemical reactions (e.g., salivary amylase, sucrase, and ATPase).
    • Proteins serve as hormones and neurotransmitters. Some examples are the hormone insulin and the neurotransmitter substance P.
    • Proteins provide support and protection aiding in the body's response to foreign substances and pathogens such as antibodies.
    • Some proteins, such as myosin and actin, are involved in muscle contraction.
    • Proteins act as carriers carrying vital substances such as hemoglobin which carries oxygen.

    Amino Acids

    • Amino acids are the monomers (building blocks) of proteins.
    • There are 20 common amino acids.
    • The liver synthesizes 10 of these.
    • 10 amino acids are considered essential as they must be consumed through diet.

    Amino Acid Structure

    • Each amino acid has an amino group (NH2), a carboxyl group (COOH), a hydrogen atom (H), and a variable side chain (R group) attached to a central carbon atom.

    Levels of Protein Structure

    • Primary Structure: The linear sequence of amino acids connected by peptide bonds.
    • Secondary Structure: The regular sub-structures (e.g., α-helices and β-sheets) of the polypeptide chain stabilized by hydrogen bonds.
    • Tertiary Structure: The three-dimensional shape of the polypeptide chain resulting from the folding of the secondary structure.
    • Quaternary Structure: The arrangement of multiple polypeptide chains to form a functional protein.

    Polypeptide Chains

    • Dipeptide: Two amino acids
    • Tripeptide: Three amino acids
    • Peptide: 4-9 amino acids
    • Polypeptide: 10 or more amino acids

    Classification of Amino Acids

    • Amino acids are classified based on their interaction with water.
    • Neutral nonpolar: Hydrophobic (interacts poorly with water) – No charge
    • Neutral polar: Hydrophilic (interacts with water) – No charge
    • Acidic: Charged negatively
    • Basic: Charged positively

    Differences in the Function of Proteins

    • Various protein shapes result in different functions.
    • The kinds and number of amino acids in the chain dictate the function.

    Protein Metabolism

    • Metabolism is the sum of all chemical processes.
    • Catabolism breaks down complex substances into simpler building blocks.
    • Anabolism is the building of complex substances from simpler ones. Digestion is an example of catabolism breaking down proteins in food into constituent amino acids which then are used in anabolism (building up) the body's protein structure.

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    Description

    Explore the fascinating world of proteins, their structure, and vital functions in the human body. This quiz delves into protein composition, the various roles they play, and the importance of amino acids in their formation. Test your knowledge about these essential macromolecules and their contributions to life.

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