42 Questions
What is the purpose of the reaction between cyanocobalamin (CN adduct) and ATP?
To form the adenylated B-12 coenzyme
What is the function of the radical species formed from the homolytic cleavage of the Co-C bond?
To participate in several enzymatically catalyzed H-transfer reactions
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
What is the primary mechanism by which bleomycin acts as an antitumor antibiotic?
By binding to DNA and, using oxygen redox chemistry, catalyzing the cleavage of the sugar-phosphate backbone
Which of the following is an example of a siderophore mentioned in the text?
Enterobactin
Which of the following is an example of a complex assembly mentioned in the text?
Photosynthetic reaction center
What is the main factor determining the orientation of ligand donor atoms in a metalloprotein?
Tertiary structure
Which type of interactions is NOT involved in the forces affecting the folding of a polypeptide into a unique 3D structure?
Glycosidic bonds
What type of structure describes the local conformation over groups of a few adjacent amino acids?
Secondary structure
What is the role of splicing in eukaryotic gene expression?
Production of mature messenger RNA
In a metalloprotein, what happens to the tertiary structure in the absence of bound metal?
It remains stable
Which protein is an example of a dimer made up of two identical subunits?
Cu-Zn superoxide dismutase
What contributes to the stability of the metal-binding site in metalloproteins?
Preorganization by tertiary structure
What promotes a transition from a partially folded form to a more completely folded form in some metal-binding proteins?
{Ca2+} binding
What does the removal of the Zn2+-binding site cause in zinc finger domains?
Alters the site of turns
How do subunits interact with each other in proteins to form larger assemblies?
By interacting with one another
Which of the following is not one of the 20 essential amino acids that make up proteins?
Helium
What is the typical configuration of the $\alpha$-carbon in amino acids found in proteins?
S
Which of the following amino acid side chains is NOT a common metal ion binding ligand in proteins?
Methyl group of Alanine
Which of the following amino acid side chains can act as a bridging ligand between two metal ions in proteins?
Thiolate of Cysteine
Which of the following is NOT a common secondary structure motif found in proteins?
Helical coil
What is the typical configuration of the peptide bonds that link amino acids in protein chains?
Trans
What is the function of messenger RNA (mRNA)?
Carrying genetic information from DNA to ribosomes
What is the purpose of cloning in genetic engineering?
Expressing cloned genes in cells to produce proteins for study
What is Vmax in enzyme kinetics?
The maximal rate of the reaction at saturating substrate levels
What are the basic structures found in RNA and DNA, respectively?
C2’ is endo to C5’ (DNA) and C3’-endo (RNA)
What is the unit comprising only a sugar and a base called?
Nucleoside
What type of RNA carries amino acids to the ribosome during protein synthesis?
Transfer RNA (tRNA)
'Hoogsteen base pairing' is responsible for which structure?
Linking two DNA strands into a double helix
'Phosphodiester linkages' join adjacent residues to form what in nucleic acids?
Sugar-phosphate polymer backbone
'Watson-Crick base-pairing interactions' are responsible for what structure in DNA?
'Double helix'
'Nucleotides' contain sugar, base, and which other group?
'Phosphate'
What is the characteristic feature of B-DNA, the most common form of DNA?
A right-handed double helix with major and minor grooves
Which of the following statements about A-DNA is true?
It has a C3'-endo sugar pucker
What is a characteristic feature of Z-DNA?
It is a left-handed variant seen for alternating purine-pyrimidine sequences
Which of the following statements about metal binding in nucleic acids is correct?
Purine N atoms are the best nucleophiles among the nucleic-acid base heteroatoms
What is the role of magnesium ions in ATP binding and hydrolysis?
Magnesium ions promote the hydrolysis of the high-energy phosphate bond in ATP and bind to the ADP thus formed
What is the structure of chromatin in eukaryotic cells?
A string of nucleosomes connected by linker DNA
What is the significance of sulfur atoms in modified nucleosides like 4-thiouridine (s4U) in RNA?
The sulfur atom can specifically bind to soft metal ions like Hg(II) or Pt(II)
What is the role of prosthetic groups in metalloproteins?
They are organic components that may also contain bound metal ions
What is the metal ion present in the coenzyme cobalamin (vitamin B-12)?
Cobalt(III)
What is the role of chlorophylls in photosynthesis?
They are magnesium complexes essential for photosynthesis
This quiz covers the composition of proteins, focusing on the naturally occurring amino acids. Topics include the structure of proteins, essential amino acids, coordination to metal ions, chirality of a-carbon, and peptide bond configuration.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
