Protein Biochemistry
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Questions and Answers

What type of amino acid is glutamic acid classified as?

  • Basic
  • Aliphatic
  • Acidic (correct)
  • Neutral
  • What is the secondary structure formed by hydrogen bonds between amino acids held in a parallel or anti-parallel conformation?

  • Tertiary structure
  • Beta sheet (correct)
  • Quaternary structure
  • Alpha helix
  • What is the function of U-turns in protein structure?

  • To form a disulfide bond
  • To form a beta sheet structure
  • To form a short loop of 3-4 amino acids (correct)
  • To form a long loop of 10-15 amino acids
  • What type of bonds hold subunits together in quaternary protein structure?

    <p>Non-covalent bonds</p> Signup and view all the answers

    What is the effect of low hemoglobin levels?

    <p>A decrease in red blood cells</p> Signup and view all the answers

    What specifies the special arrangements of the secondary structure?

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

    What type of mutation can lead to misfolding of proteins, as seen in Sickle cell disease?

    <p>Point mutation</p> Signup and view all the answers

    What is the characteristic secondary structure of the abnormal PrPC protein in Prions?

    <p>Beta sheet</p> Signup and view all the answers

    Which disease is associated with the accumulation of amyloid deposits?

    <p>Alzheimer's Disease</p> Signup and view all the answers

    What is the term for proteins that have folded abnormally and aggregated together?

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

    What is the normal function of the PrPC protein?

    <p>Cell adhesion, ion channel activity, and neuronal excitability</p> Signup and view all the answers

    What is the result of abnormal PrPC converting normal PrPC into an abnormal form?

    <p>A chain reaction</p> Signup and view all the answers

    How many different proteins can form amyloid deposits?

    <p>30</p> Signup and view all the answers

    What is the typical secondary structure of the normal PrPC protein?

    <p>Alpha helix</p> Signup and view all the answers

    Which amino acid is always found at the N-terminus of a polypeptide chain?

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

    Which of the following amino acids contains a free sulfhydryl group that can form disulfide bonds?

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

    What is the primary structure of a protein?

    <p>The sequence of amino acids in the protein</p> Signup and view all the answers

    Which of these groups does the amino acid tyrosine belong to?

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

    Why are the peptide bonds that link amino acids together in a polypeptide chain unable to rotate freely?

    <p>The peptide bonds are rigid due to the double-bond character of the C-N bond.</p> Signup and view all the answers

    Which statement about the stereoisomers of α-amino acids is TRUE?

    <p>L-amino acids and D-amino acids are mirror images of each other.</p> Signup and view all the answers

    Study Notes

    Protein Structure

    • Hydrogen bonds hold the beta-sheet structure in the correct conformation
    • Beta-sheet structure is parallel or anti-parallel

    Beta Turns

    • Formed by 3-4 amino acids, commonly glycine and proline
    • Create a short loop

    Tertiary Structure

    • Specifies the special arrangements of the secondary structure
    • Acidic amino acid: glutamic acid
    • Basic amino acid: lysine

    Quaternary Protein Structure

    • Consists of several subunits held together by non-covalent bonds
    • Example: Haemoglobin

    Haemoglobin

    • Abnormal levels can indicate anemia (reduced level of red blood cells)

    Amino Acids

    • α-amino acids contain an asymmetric carbon
    • 2 stereoisomers exist (enantiomers/optical isomers)
    • Proteins in all life only contain L-amino acid enantiomers
    • The surface of proteins is asymmetric, allowing for highly specific molecular recognition

    Groups of Amino Acids

    • Non-polar and hydrophobic
    • Aromatic (phenylalanine and tryptophan are non-polar and hydrophobic; tyrosine is polar and hydrophobic)
    • Polar, hydrophilic, and acidic
    • Polar, hydrophilic, and basic
    • Hydroxylic, sulphur-containing, and amidic

    Methionine and Cysteine

    • Both contain sulphur
    • Methionine is always the first amino acid in a polypeptide chain
    • The free sulphydryl group of cysteine is highly reactive and often used in enzyme active sites
    • Cysteine can form disulfide bonds

    Primary Protein Structure

    • The linear sequence of amino acid residues from the N- to the C-terminus
    • Formed through peptide bonds between amino acids
    • Peptide bonds cannot rotate freely

    Abnormal Protein Structure

    • Can affect protein function
    • Examples: sickle cell disease (point mutation leading to misfolding), cystic fibrosis (point mutation leading to trapping of protein in the ER), and Duchene muscular dystrophy (point mutation leading to premature stop codons)

    Abnormal Secondary Structure

    • Can affect protein function
    • Example: Amyloidosis (abnormal folding and aggregation of proteins, forming extracellular deposits)
    • Prions (proteinaceous infectious particles, no DNA/RNA)
    • Prion protein (PrPC) abnormal form can convert normal PrPC into abnormal form in a chain reaction

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    UM1010_ProteinBiochemistry.pptx

    Description

    Quiz on protein structure, covering hydrogen bonds, beta-sheet structure, beta turns, tertiary structure, and quaternary protein structure. Explore the arrangement of amino acids and their properties.

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