Proteins and Amino Acids Composition
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Questions and Answers

What is the purpose of the reaction between cyanocobalamin (CN adduct) and ATP?

  • To cleave the Co-C bond and form radical species
  • To form the adenylated B-12 coenzyme (correct)
  • To transfer a CH3 ion to Hg, Pb, and Sn salts
  • To catalyze the cleavage of the sugar-phosphate backbone of DNA
  • What is the function of the radical species formed from the homolytic cleavage of the Co-C bond?

  • To facilitate the specific uptake of iron by microorganisms
  • To catalyze the cleavage of the sugar-phosphate backbone of DNA
  • To transfer a CH3 ion to Hg, Pb, and Sn salts
  • To participate in several enzymatically catalyzed H-transfer reactions (correct)
  • What is the primary function of siderophores secreted by microorganisms?

  • To bind Fe3+ ion with high affinity and produce soluble complexes that can be taken up by the organism (correct)
  • To transfer a CH3 ion to Hg, Pb, and Sn salts in aqueous solution
  • To participate in several enzymatically catalyzed H-transfer reactions
  • To catalyze the cleavage of the sugar-phosphate backbone of DNA
  • What is the primary mechanism by which bleomycin acts as an antitumor antibiotic?

    <p>By binding to DNA and, using oxygen redox chemistry, catalyzing the cleavage of the sugar-phosphate backbone</p> Signup and view all the answers

    Which of the following is an example of a siderophore mentioned in the text?

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

    Which of the following is an example of a complex assembly mentioned in the text?

    <p>Photosynthetic reaction center</p> Signup and view all the answers

    What is the main factor determining the orientation of ligand donor atoms in a metalloprotein?

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

    Which type of interactions is NOT involved in the forces affecting the folding of a polypeptide into a unique 3D structure?

    <p>Glycosidic bonds</p> Signup and view all the answers

    What type of structure describes the local conformation over groups of a few adjacent amino acids?

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

    What is the role of splicing in eukaryotic gene expression?

    <p>Production of mature messenger RNA</p> Signup and view all the answers

    In a metalloprotein, what happens to the tertiary structure in the absence of bound metal?

    <p>It remains stable</p> Signup and view all the answers

    Which protein is an example of a dimer made up of two identical subunits?

    <p>Cu-Zn superoxide dismutase</p> Signup and view all the answers

    What contributes to the stability of the metal-binding site in metalloproteins?

    <p>Preorganization by tertiary structure</p> Signup and view all the answers

    What promotes a transition from a partially folded form to a more completely folded form in some metal-binding proteins?

    <p>{Ca2+} binding</p> Signup and view all the answers

    What does the removal of the Zn2+-binding site cause in zinc finger domains?

    <p>Alters the site of turns</p> Signup and view all the answers

    How do subunits interact with each other in proteins to form larger assemblies?

    <p>By interacting with one another</p> Signup and view all the answers

    Which of the following is not one of the 20 essential amino acids that make up proteins?

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

    What is the typical configuration of the $\alpha$-carbon in amino acids found in proteins?

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

    Which of the following amino acid side chains is NOT a common metal ion binding ligand in proteins?

    <p>Methyl group of Alanine</p> Signup and view all the answers

    Which of the following amino acid side chains can act as a bridging ligand between two metal ions in proteins?

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

    Which of the following is NOT a common secondary structure motif found in proteins?

    <p>Helical coil</p> Signup and view all the answers

    What is the typical configuration of the peptide bonds that link amino acids in protein chains?

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

    What is the function of messenger RNA (mRNA)?

    <p>Carrying genetic information from DNA to ribosomes</p> Signup and view all the answers

    What is the purpose of cloning in genetic engineering?

    <p>Expressing cloned genes in cells to produce proteins for study</p> Signup and view all the answers

    What is Vmax in enzyme kinetics?

    <p>The maximal rate of the reaction at saturating substrate levels</p> Signup and view all the answers

    What are the basic structures found in RNA and DNA, respectively?

    <p>C2’ is endo to C5’ (DNA) and C3’-endo (RNA)</p> Signup and view all the answers

    What is the unit comprising only a sugar and a base called?

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

    What type of RNA carries amino acids to the ribosome during protein synthesis?

    <p>Transfer RNA (tRNA)</p> Signup and view all the answers

    'Hoogsteen base pairing' is responsible for which structure?

    <p>Linking two DNA strands into a double helix</p> Signup and view all the answers

    'Phosphodiester linkages' join adjacent residues to form what in nucleic acids?

    <p>Sugar-phosphate polymer backbone</p> Signup and view all the answers

    'Watson-Crick base-pairing interactions' are responsible for what structure in DNA?

    <p>'Double helix'</p> Signup and view all the answers

    'Nucleotides' contain sugar, base, and which other group?

    <p>'Phosphate'</p> Signup and view all the answers

    What is the characteristic feature of B-DNA, the most common form of DNA?

    <p>A right-handed double helix with major and minor grooves</p> Signup and view all the answers

    Which of the following statements about A-DNA is true?

    <p>It has a C3'-endo sugar pucker</p> Signup and view all the answers

    What is a characteristic feature of Z-DNA?

    <p>It is a left-handed variant seen for alternating purine-pyrimidine sequences</p> Signup and view all the answers

    Which of the following statements about metal binding in nucleic acids is correct?

    <p>Purine N atoms are the best nucleophiles among the nucleic-acid base heteroatoms</p> Signup and view all the answers

    What is the role of magnesium ions in ATP binding and hydrolysis?

    <p>Magnesium ions promote the hydrolysis of the high-energy phosphate bond in ATP and bind to the ADP thus formed</p> Signup and view all the answers

    What is the structure of chromatin in eukaryotic cells?

    <p>A string of nucleosomes connected by linker DNA</p> Signup and view all the answers

    What is the significance of sulfur atoms in modified nucleosides like 4-thiouridine (s4U) in RNA?

    <p>The sulfur atom can specifically bind to soft metal ions like Hg(II) or Pt(II)</p> Signup and view all the answers

    What is the role of prosthetic groups in metalloproteins?

    <p>They are organic components that may also contain bound metal ions</p> Signup and view all the answers

    What is the metal ion present in the coenzyme cobalamin (vitamin B-12)?

    <p>Cobalt(III)</p> Signup and view all the answers

    What is the role of chlorophylls in photosynthesis?

    <p>They are magnesium complexes essential for photosynthesis</p> Signup and view all the answers

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