Amino Acids & Proteins Quiz
21 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary factor that dictates the degree of rotation in a peptide bond?

  • The type of electrostatic interactions between side chains
  • The size of the R-groups attached to the amino acids (correct)
  • The stability of the peptide bond itself
  • The presence of hydrogen bonds

    • Which of the following interactions is responsible for the spontaneous avoidance of water by hydrophobic side chains in proteins?

  • Hydrophobic interactions (correct)
  • Disulfide bonds
  • Hydrogen bonding
  • Electrostatic interactions

    • What type of interaction is responsible for the formation of a disulfide bond between cysteine residues in a protein?

  • Covalent bonding (correct)
  • Hydrogen bonding
  • Ionic bonding
  • Van der Waals interactions

    • Which of the following describes a protein composed of multiple identical polypeptide chains?

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

    Which of the following proteins is an example of a heterooligomer?

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

    Which of the following amino acids would most likely be found in the interior of a globular protein?

    <p>Valine (D)</p> Signup and view all the answers

    Which of the following statements correctly describes the relationship between the tertiary structure of a protein and its function?

    <p>The tertiary structure is determined by the protein's primary sequence. (A)</p> Signup and view all the answers

    Which of the following is a key difference between alpha-helices and beta-sheets?

    <p>Alpha-helices are formed by hydrogen bonds between peptide bonds in the same chain, while beta-sheets are formed by hydrogen bonds between peptide bonds in different chains. (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of secondary structure in proteins?

    <p>It involves interactions between side chains of amino acids. (B)</p> Signup and view all the answers

    What is the main difference between the tertiary and quaternary structure of a protein?

    <p>Tertiary structure is the 3-dimensional structure of a single polypeptide chain, while quaternary structure is the arrangement of multiple polypeptide chains. (C)</p> Signup and view all the answers

    Which of the following proteins has a high proportion of alpha-helices?

    <p>Myoglobin (C)</p> Signup and view all the answers

    Which of the following statements is TRUE about globular proteins?

    <p>They often have domains with specific functions. (A)</p> Signup and view all the answers

    What is the main force that drives the formation of secondary structures like alpha-helices and beta-sheets?

    <p>Hydrogen bonds (D)</p> Signup and view all the answers

    Which amino acid classification is based on the chemical properties of the "R" group and includes categories like hydrophobic and non-polar?

    <p>Polarity and Charge (C)</p> Signup and view all the answers

    Which amino acid class includes those with a cyclic "R" group?

    <p>Imino acids (C)</p> Signup and view all the answers

    Which characteristic of amino acids allows them to be detected in colorless solutions using UV light?

    <p>The presence of conjugated double bonds in their &quot;R&quot; groups (C)</p> Signup and view all the answers

    Which of the following statements is NOT TRUE regarding proteins?

    <p>Proteins are always soluble in organic solvents due to their polar groups. (A)</p> Signup and view all the answers

    What is the primary structure of a protein?

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

    Which amino acid class contains cysteine and methionine?

    <p>Amino acids containing sulfur (D)</p> Signup and view all the answers

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

    <p>Their melting point is generally low due to their non-polar nature. (A)</p> Signup and view all the answers

    Which of the following amino acids is NOT classified as an acidic amino acid?

    <p>Lysine (Lys) (D)</p> Signup and view all the answers

    Flashcards

    Amino Acid

    The basic unit of a protein, characterized by an R group.

    R Group Classification

    Classifies amino acids based on the chemical properties of their R groups.

    Hydrophobic Amino Acids

    Amino acids that are non-polar and repel water.

    Polar Amino Acids

    Amino acids that have a charge or are uncharged but can interact with water.

    Signup and view all the flashcards

    Aromatic Amino Acids

    Amino acids that contain an aromatic ring and absorb UV light.

    Signup and view all the flashcards

    Zwitterions

    Amino acids that can carry both positive and negative charges.

    Signup and view all the flashcards

    Globular Proteins

    Proteins that are spherical and usually function as enzymes or transport molecules.

    Signup and view all the flashcards

    Primary Structure

    The linear sequence of amino acids in a protein.

    Signup and view all the flashcards

    Peptide Bond Rotation

    The degree of rotation in peptides is limited by the characteristics of the peptide bond, which has a double bond nature.

    Signup and view all the flashcards

    Hydrophobic Interactions

    These occur between hydrophobic side chains, which tend to avoid water and are often found in protein cores.

    Signup and view all the flashcards

    Electrostatic Interactions

    Forces that occur between charged side chains, such as COO- and NH+ groups, influencing protein structure.

    Signup and view all the flashcards

    Disulfide Bond

    Covalent bonds formed between cysteine residues, linking polypeptide chains, enhancing protein stability.

    Signup and view all the flashcards

    Quaternary Structure

    The overall structure formed by multiple polypeptide chains (subunits) that join together to create a larger protein.

    Signup and view all the flashcards

    Secondary Structure

    Local conformations of the polypeptide chain stabilized by hydrogen bonds between backbone atoms.

    Signup and view all the flashcards

    Super Secondary Structure

    The specific arrangement of secondary structures in proteins, forming motifs.

    Signup and view all the flashcards

    Tertiary Structure

    The 3D structure of a protein formed from interactions between distant amino acids in the sequence.

    Signup and view all the flashcards

    Alpha Helix

    A coiled structure formed by hydrogen bonding between C=O and N-H groups, typically containing ~11 amino acids.

    Signup and view all the flashcards

    Beta Structure

    A folding pattern in proteins characterized by hydrogen bonds, forming beta-pleated sheets, can be parallel or anti-parallel.

    Signup and view all the flashcards

    Polar and Charged Amino Acids

    Amino acids found on the protein surface interacting with water; can be charged or neutral.

    Signup and view all the flashcards

    Study Notes

    Amino Acids & Proteins

    • Amino acids are the basic units of proteins.
    • Amino acids have a central carbon atom (α-carbon) bonded to an amino group (+H₃N), a carboxyl group (-COOH), a hydrogen atom, and a side chain (R-group).
    • The R-group differentiates the 20 naturally occurring amino acids.
    • Amino acids exhibit stereoisomerism (D/L).
    • L-amino acids are the building blocks of proteins.
    • Amino acids are classified based on the chemical properties of their R-groups.
    • This includes hydrophobicity/hydrophilicity, charge (acidic/basic), and polarity.
    • Aliphatic amino acids (leu, ile, ala, val) are nonpolar.
    • Aromatic amino acids (phe, trp, tyr) are nonpolar.
    • Amino acids with sulfur (cys, met) are nonpolar.
    • Amino acids with hydroxyl groups (thr, ser) are polar.
    • Acidic amino acids (asp, glu) are polar and negatively charged.
    • Basic amino acids (lys, arg, his) are polar and positively charged.
    • Imino acid (pro) has a cyclic R-group, non-polar
    • Amides (Gln, Asn) are polar.
    • Proteins are biopolymers of amino acids.
    • Different proteins contain varying numbers of amino acids, ranging from less than 100 to several thousands.

    Peptide Bond Formation

    • A peptide bond is formed between the carboxyl group of one amino acid and the amino group of another.
    • This results in the removal of a water molecule.
    • The peptide bond is planar, with partial double bond characteristics.

    Protein Structure

    • Proteins have four levels of structure: primary, secondary, tertiary, and quaternary.
    • The primary structure is the linear sequence of amino acids.
    • Secondary structures result from hydrogen bonding between the backbone atoms.
    • Common secondary structures include α-helices and β-sheets.
    • α-helices are right-handed coils, with approximately 3.6 amino acids per turn. β-sheets are formed from parallel or antiparallel strands, stabilized by hydrogen bonds.
    • Super secondary structures are combinations of secondary structures.
    • Tertiary structure is the overall 3D arrangement of the polypeptide chain.
    • Stabilized by interactions between amino acid side chains (hydrophobic interactions, hydrogen bonding, ionic bonds, disulfide bonds, and van der Waals interactions).
    • Proteins can be globular or fibrous.
    • Globular proteins have compact, folded structures; often involved in metabolic processes.
    • Fibrous proteins have elongated structures; often play structural roles.
    • Conjugated proteins have a non-protein moiety (e.g., heme in hemoglobin).
    • Quaternary structure is the arrangement of multiple polypeptide chains in a protein (e.g., hemoglobin has 4 polypeptide chains).

    Forces Influencing Protein Structure

    • Hydrogen bonds: occur between H attached to electronegative atoms and another electronegative atom .
    • Hydrophobic interactions: nonpolar amino acid side chains cluster together in the protein interior, minimizing contact with water.
    • Ionic bonds/electrostatic interactions: occur between charged side chains.
    • Disulfide bonds: Covalent bonds formed between two cysteine residues.
    • Van der Waals forces/dipole-dipole interactions: weak attractive forces between all atoms in close proximity.
    • These forces determine the 3D shape of the protein, and are particularly important in maintaining the tertiary structure.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Basic and General Biochemistry Amino Acid and Protein PDF

    Description

    Test your knowledge on amino acids and their role in proteins. This quiz covers the structure, classification, and properties of different amino acids. Explore how these essential building blocks contribute to protein functions and characteristics.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser