Glycine
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Questions and Answers

Which method is commonly used to sequence amino acids in proteins?

  • Edman degradation (correct)
  • Protease cleavage
  • The Merrifield method
  • Mass spectrometry

    • What can mass spectrometry measure in proteins?

  • Tertiary structure
  • Molecular mass (correct)
  • Secondary structure
  • Quaternary structure

    • Which level of protein structure refers to the 3D folding of a polypeptide?

  • Tertiary structure (correct)
  • Quaternary structure
  • Primary structure
  • Secondary structure

    • What is the primary function of protein sequencing techniques?

    <p>To determine the amino acid sequence of proteins</p> Signup and view all the answers

    What is the term for homologous proteins in the same species?

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

    What does bioinformatics help identify in new proteins?

    <p>Functional segments</p> Signup and view all the answers

    Which amino acid residue is the most common in protein molecules?

    <p>L-isomers</p> Signup and view all the answers

    Which type of amino acid R group is the most hydrophilic?

    <p>Positively charged</p> Signup and view all the answers

    Which amino acid residue can form disulfide bonds?

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

    Which amino acid residue has an ionizable side chain with pKa near neutrality?

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

    Which type of amino acid R group absorbs UV light at 270-280 nm?

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

    What is the isoelectric point (pI) of an amino acid?

    <p>The pH at which the net electric charge is zero</p> Signup and view all the answers

    Which of the following is true about proteins?

    <p>All of the above</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.</p> Signup and view all the answers

    How are amino acids joined together in proteins?

    <p>Through peptide bonds.</p> Signup and view all the answers

    What is the role of enzymes in cells?

    <p>Enzymes catalyze chemical reactions in cells.</p> Signup and view all the answers

    How can individual proteins be separated from other proteins in a cell?

    <p>Based on their amino acid sequences.</p> Signup and view all the answers

    What is the function of antibodies in the body?

    <p>Antibodies defend against foreign invaders.</p> Signup and view all the answers

    Which step in protein purification involves selectively precipitating proteins based on their lower solubility in salt?

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

    Which chromatography technique separates proteins based on their size?

    <p>Size-Exclusion Chromatography</p> Signup and view all the answers

    Which chromatography technique uses high-pressure pumps to improve resolution?

    <p>High-Performance Liquid Chromatography</p> Signup and view all the answers

    Which chromatography technique separates proteins based on their binding affinity?

    <p>Affinity Chromatography</p> Signup and view all the answers

    What does electrophoresis visualize and characterize in purified proteins?

    <p>Approximate molecular weight</p> Signup and view all the answers

    What is the purpose of sodium dodecyl sulfate (SDS) in electrophoresis?

    <p>To partially unfold proteins</p> Signup and view all the answers

    Which of the following is true about glycine's titration curve?

    <p>Glycine has two buffer regions</p> Signup and view all the answers

    What is the isoelectric point (pI) of an amino acid?

    <p>The pH at which the net charge is zero</p> Signup and view all the answers

    Which amino acid has an R group with a pKa of 6.0?

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

    What is the difference between a peptide and a protein?

    <p>Peptides have fewer amino acid residues than proteins</p> Signup and view all the answers

    What are conjugated proteins?

    <p>Proteins that contain permanently associated chemical components</p> Signup and view all the answers

    What is the most common form of amino acid residues in protein molecules?

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

    Why is a pure protein preparation essential for studying a protein's properties?

    <p>To determine the protein's properties and activities accurately</p> Signup and view all the answers

    What is the primary function of protein sequencing techniques?

    <p>To determine the order of amino acids in a protein</p> Signup and view all the answers

    What is the term for modified amino acids that contribute to a protein's function?

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

    What is the main factor that determines the solubility of amino acids in water?

    <p>The structure and properties of their R groups</p> Signup and view all the answers

    What is the isoelectric point (pI) of an amino acid?

    <p>The pH at which the net electric charge is zero</p> Signup and view all the answers

    What is the main function of histidine residues in proteins?

    <p>To serve as proton donors/acceptors in enzyme-catalyzed reactions</p> Signup and view all the answers

    What is the primary structure of a protein?

    <p>The linear sequence of amino acids.</p> Signup and view all the answers

    What is the isoelectric point (pI) of an amino acid?

    <p>The pH at which the amino acid has no net charge.</p> Signup and view all the answers

    Which of the following is true about proteins?

    <p>Proteins are composed of a common set of 20 amino acids.</p> Signup and view all the answers

    How can individual proteins be separated from other proteins in a cell?

    <p>By differences in their chemical and functional properties.</p> Signup and view all the answers

    What does electrophoresis visualize and characterize in purified proteins?

    <p>The size of proteins.</p> Signup and view all the answers

    Which chromatography technique uses high-pressure pumps to improve resolution?

    <p>High-performance liquid chromatography (HPLC).</p> Signup and view all the answers

    Which method is commonly used to separate proteins based on their size?

    <p>Size-Exclusion Chromatography</p> Signup and view all the answers

    Which level of protein structure is responsible for the 3D folding of a polypeptide?

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

    What is the purpose of dialysis in protein purification?

    <p>To separate proteins from small solutes</p> Signup and view all the answers

    What is the role of sodium dodecyl sulfate (SDS) in electrophoresis?

    <p>To give all proteins a similar charge-to-mass ratio</p> Signup and view all the answers

    What is the primary function of mass spectrometry in studying proteins?

    <p>To measure molecular mass, sequence short amino acid sequences, and document the entire cellular proteome</p> Signup and view all the answers

    What is the function of affinity chromatography in protein purification?

    <p>To separate proteins based on their binding affinity</p> Signup and view all the answers

    What is the purpose of labeling amino-terminal α-amino group and ε-amino group of lysine residues in protein structure studies?

    <p>To track specific amino acid residues</p> Signup and view all the answers

    What is the role of bioinformatics in studying proteins?

    <p>To identify functional segments in new proteins</p> Signup and view all the answers

    What does electrophoresis visualize and characterize in purified proteins?

    <p>The degree of purity of proteins</p> Signup and view all the answers

    What is the term for homologous proteins in different species?

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

    What can be monitored during enzyme purification by assaying specific activity?

    <p>The number of enzyme units per mg of total protein</p> Signup and view all the answers

    What is the term for certain protein segments that are specific to a taxonomic group?

    <p>Signature sequences</p> Signup and view all the answers

    Which of the following is true about the isoelectric point (pI) of an amino acid?

    <p>The pI is the pH at which the net charge of the amino acid is zero</p> Signup and view all the answers

    Which type of amino acid R group is the most hydrophilic?

    <p>Amino acids with polar R groups</p> Signup and view all the answers

    What is the primary function of antibodies in the body?

    <p>To recognize and neutralize foreign substances</p> Signup and view all the answers

    What is the role of enzymes in cells?

    <p>To catalyze biochemical reactions</p> Signup and view all the answers

    What does electrophoresis visualize and characterize in purified proteins?

    <p>Protein size and charge</p> Signup and view all the answers

    What can mass spectrometry measure in proteins?

    <p>Protein mass and sequence</p> Signup and view all the answers

    Study Notes

    Protein Structure and Sequencing

    • Amino acid sequencing is commonly done using mass spectrometry.
    • The primary function of protein sequencing techniques is to determine the order of amino acids in a protein.
    • The primary structure of a protein refers to the sequence of amino acids.

    Protein Properties

    • The isoelectric point (pI) of an amino acid is the pH at which the amino acid has no net charge.
    • The pI of an amino acid is important for understanding protein behavior and function.
    • Glycine has a unique titration curve compared to other amino acids.
    • Histidine residues play a crucial role in protein function, particularly in enzyme active sites.

    Amino Acid Properties

    • The most common amino acid residue in protein molecules is alanine.
    • The most hydrophilic type of amino acid R group is the hydroxyl (-OH) group.
    • Cysteine residues can form disulfide bonds, which are important for protein structure and function.
    • Tyrosine residues have an ionizable side chain with a pKa near neutrality.
    • The amino acid tryptophan has an R group that absorbs UV light at 270-280 nm.

    Protein Purification and Separation

    • Individual proteins can be separated from other proteins in a cell using techniques such as chromatography and electrophoresis.
    • Electrophoresis visualizes and characterizes proteins based on their size and charge.
    • The purpose of sodium dodecyl sulfate (SDS) in electrophoresis is to denature proteins and improve separation.
    • Chromatography techniques include size exclusion, ion exchange, and affinity chromatography, which separate proteins based on size, charge, and binding affinity, respectively.
    • High-pressure liquid chromatography (HPLC) is a type of chromatography that uses high-pressure pumps to improve resolution.

    Protein Function and Bioinformatics

    • Enzymes play a crucial role in cells by catalyzing biochemical reactions.
    • Antibodies are proteins that help the body fight infection and disease by recognizing and binding to specific pathogens.
    • Bioinformatics helps identify functional domains and motifs in new proteins.
    • The primary function of mass spectrometry in studying proteins is to measure protein mass and identify post-translational modifications.
    • Affinity chromatography is a technique used to purify proteins based on their binding affinity for specific molecules.

    Conjugated Proteins and Post-Translational Modifications

    • Conjugated proteins are proteins that have been modified by the addition of a non-protein molecule, such as a carbohydrate or lipid.
    • Modified amino acids that contribute to a protein's function are referred to as post-translational modifications.
    • The most common form of amino acid residues in protein molecules is the L-isomer.
    • The main factor that determines the solubility of amino acids in water is the polarity of the R group.

    Protein Expression and Evolution

    • Homologous proteins are proteins that share a common evolutionary origin.
    • Orthologous proteins are homologous proteins that are found in different species.
    • Paralogous proteins are homologous proteins that are found in the same species.
    • The term for certain protein segments that are specific to a taxonomic group is a protein domain.

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    Related Documents

    Week 3-Amino acids-Peptides-Proteins - Short (1).pptx

    Description

    Test your knowledge on the properties of glycine and its role as a buffer in the body. Learn about the point of inflection in its titration curve, the effect of the chemical environment on its pKa, and the acidity of its α-carboxyl group.

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