Description : Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin
Last Answer : Answer : C
Description : eIF-1A and eIF-3 are required (A) For binding of amino acyl tRNA to 40 S ribosomal subunit (B) For binding of mRNA to 40 S ribosomal subunit (C) For binding of 60 S subunit to 40 S subunit (D) To prevent binding of 60 S subunit to 40 S subunit
Last Answer : Answer : D
Description : Erythromycin binds to 50 S ribosomal sub unit and (A) Inhibits binding of amino acyl tRNA (B) Inhibits Peptidyl transferase activity (C) Inhibits translocation (D) Causes premature chain termination
Description : The mechanism of antibacterial action of tetracycline involves (a) Binding to a component of the 50S ribosomal subunit (b) Inhibition of translocase activity (c) Blockade of binding of ... (d) Selective inhibition of ribosomal peptidyl transferases (e) Inhibition of DNA-dependent RNA polymerase
Last Answer : Ans: C
Description : During translation initiation in prokaryotes, a GTP molecule is needed in (a) formation of formyl-met-tRNA (b) binding of 30S subunit of ribosome with mRNA (c) association of 30S mRNA with formyl-met- tRNA (d) association of 50S subunit of ribosome with initiation complex.
Last Answer : (c) association of 30S mRNA with formyl-met- tRNA
Description : .During translation initiation in prokaryotes, a GTP molecule is needed in (a) formation of formyl-met-tRNA (b) binding of 30S subunit of ribosome with mRNA (c) association of 30S mRNA with formyl-met- tRNA (d) association of 50S subunit of ribosome with initiation complex.
Description : Which binding is inhibited by pactamycin? A- Aminoacyl-tRNA to the A-site of 30S subunit B- Initiator-tRNA to 30S/40S initiation complexes C- Peptidyl t-RNA to the 50S subunit D- Formation of peptide bond in P site
Last Answer : Initiator-tRNA to 30S/40S initiation complexes
Description : The antibiotic which has a structure similar to the amino acyl end of tRNA tyrosine is (A) Actinomycin d (B) Streptomycin (C) Puromycin (D) Mitomycin c
Description : Peptidyl transferase activity is present in (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) eEF-2 (D) Amino acyl tRNA
Last Answer : Answer : B
Description : The first amino acyl tRNA approaches 40 S ribosomal subunit in association with (A) eIF-1A and GTP (B) eIF-2 and GTP (C) eIF-2C and GTP (D) eIF-3 and GTP
Description : Eukaryotic initiation factors 4A, 4B and 4F bind to (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) mRNA (D) Amino acyl tRNA
Description : Two drugs that affect cell wall synthesis are a. Erythromycin and penicillin. b. Vancomycin and cephalosporin. c. Tetracycline and polymyxin b. d. Chloramphenicol and streptomycin.
Last Answer : a. Erythromycin and penicillin.
Description : Select the antibiotic which inhibits bacterial protein synthesis by interfering with translocation of elongating peptide chain from acceptor site back to the peptidyl site of the ribosome so that ... chain is prematurely terminated: A. Chloramphenicol B. Erythromycin C. Tetracycline D. Streptomycin
Last Answer : B. Erythromycin
Description : The following antibiotic accentuates the nuromuscular blockade produced by pancuronium: A. Streptomycin B. Erythromycin C. Penicillin G D. Chloramphenicol
Last Answer : A. Streptomycin
Description : In eukaryotic cells (A) Formylated tRNA is important for initiation of translation (B) Cyclohexamide blocks elongation during translation (C) Cytosolic ribosomes are smaller than those found in prokaryotes (D) Erythromycin inhibits elongation during translation
Description : The primary mechanism underlying the resistance of gram-positive organisms to macrolide antibiotics is (a) Methylation of binding sites on the 50S ribosomal subunit (b) Formation of ... ) Formation of drug-inactivating acetyltranferases (e) Decreased drug permeability of the cytoplasmic membrane
Last Answer : Ans: A
Description : The binding of prokaryotic DNA dependent RNA polymerase to promoter sits of genes is inhibited by the antibiotic: (A) Streptomycin (B) Rifamcin (C) Aueromycin (D) Puromycin
Description : The binding of prokaryotic DNA dependent RNA polymerase to promoter sites of genes is inhibited by the antibiotic: (A) Puromycin (B) Rifamycin (C) Terramycin (D) Streptomycin
Description : Tetracylin prevents synthesis of polypeptide by (A) Blocking mRNA formation from DNA (B) Releasing peptides from mRNA-tRNA complex (C) Competing with mRNA for ribosomal binding sites (D) Preventing binding of aminoacyl tRNA
Description : Initiation of protein synthesis begins with binding of (A) 40S ribosomal unit on mRNA (B) 60S ribosomal unit (C) Charging of tRNA with specific amino acid (D) Attachment of aminoacyl tRNA on mRNA
Last Answer : Answer : A
Description : Which antibiotic inhibits interaction between tRNA and mRNA during bacterial protein synthesis? (a) Tetracycline (b) Erythromycin (c) Neomycin (d) Streptomycin
Last Answer : (d) Streptomycin
Description : .Which antibiotic inhibits interaction between tRNA and mRNA during bacterial protein synthesis? (a) Tetracycline (b) Erythromycin (c) Neomycin (d) Streptomycin
Last Answer : (c) Neomycin
Description : The antibiotic which cleaves DNA is (A) Actinomycin d (B) Streptomycin (C) Puromycin (D) Mitomycin C
Description : The antibiotic which inhibits DNA dependent RNA polymerase is (A) Mitomycin C (B) Actinomycin d (C) Streptomycin (D) Puromycin
Description : Erythromycin acts on ribosomes and inhibit (A) Formation of initiation complex (B) Binding of aminoacyl tRNA (C) Peptidyl transferase activity (D) Translocation
Description : Bacteria become erythromycin resistant by the following mechanisms except: A. Becoming less permeable to erythromycin B. Elaborating an erythromycin esterase enzyme C. Elaborating a protection ... the erythromycin binding site D. Altering the ribosomal binding site through a methylase enzyme
Last Answer : C. Elaborating a ‘protection protein’ which blocks the erythromycin binding site
Description : In prokaryotes, the ribosomal subunits are (A) 30 S and 40 S (B) 40 S and 50 S (C) 30 S and 50 S (D) 40 S and 60 S
Description : Chloramphenicol inhibits bacterial protein synthesis by: A. Binding to 30S ribosome and inhibiting attachment of aminoacyl tRNA B. Binding to 50S ribosome and preventing peptide bond formation C. Binding to ... chain D. Binding to both 30S and 50S ribosome and inducing misreading of mRNA code
Last Answer : B. Binding to 50S ribosome and preventing peptide bond formation
Description : Tetracyclines inhibit binding of amino acyl tRNAs to (A) 30 S ribosomal subunits (B) 40 S ribosomal subunits (C) 50 S ribosomal subunits (D) 60 S ribosomal subunits
Description : What is the action of tetracycline in prokaryotes? A- It blocks translocation reaction on ribosomes B- It blocks peptidyltransferase reaction on ribosomes C- It blocks the binding of amino-acyl tRNA to the A site of ribosomes D- Not known with certainity
Last Answer : It blocks the binding of amino-acyl tRNA to the A site of ribosomes
Description : Antibacterial agents can be classified with regard to their structure, mechanism of action, and activity pattern against various types of bacterial pathogens. Which of the following ... are both bacteriostatic d. Sulfonamides and trimethoprim act synergistically to inhibit purine synthesis
Last Answer : Answer: a, b, d Penicillins, cephalosporins, and monobactams possess a b-lactam ring of some type and act to bind bacterial division plate proteins, thus inhibiting cell wall ... act in different mechanisms to inhibit protein synthesis, therefore two agents in combination act synergistically
Description : In prokaryotes, chloramphenicol (A) Causes premature release of the polypeptide chain (B) Causes misreading of the mRNA (C) Depolymerises DNA (D) Inhibits peptidyl transferase activity
Description : Mitochondrial protein synthesis is inhibited by (A) Cycloheximide (B) Chloramphenicol (C) Diptheria toxin (D) None of these
Description : Purine biosynthesis is inhibited by (A) Aminopterin (B) Tetracyclin (C) Methotrexate (D) Chloramphenicol
Description : Hormone receptors that stimulate cAMP production (A) are part of a complex of two proteins that transform the external signal into internal cAMP production (B) are proteins distinct and separate from those ... binding of the hormone (D) are not very specific and bind a number of different hormones
Description : The nucleotide binding site of G-proteins is present on their (A) α-Subunit (B) β-Subunit α- and β- (C) γ-Subunit (D) δ-Subunit
Description : Peptidyl transferase activity is located in (A) Elongation factor (B) A charged tRNA molecule (C) Ribosomal protein (D) A soluble cytosolic protein
Description : The newly entering amino acyl tRNA into A site requires (A) EF-II (B) Ribosomal RNA (C) mRNA (D) EF-I
Description : mRNA is complementary to the nucleotide sequence of (A) Coding strand (B) Ribosomal RNA (C) tRNA (D) Template strand
Description : Thymine is present in (A) tRNA (B) Ribosomal RNA (C) Mammalian mRNA(D) Prokaryotic mRNA
Description : If an antibiotic binds to a 50S subunit, what cellular process will be inhibited? a. DNA replication b. Intron excision c. Translation d. Transcription
Last Answer : c. Translation
Description : The most important mechanism by which gram negative bacilli acquire chloramphenicol resistance is (a) Decreased permeability into the bacterial cell (b) Acquisition of a plasmid encoded ... bacterial ribosome for chloramphenicol (d) Switching over from ribosomal to mitochondrial protein synthesis
Last Answer : Ans: B
Description : The most important mechanism by which gram negative bacilli acquire chloramphenicol resistance is: A. Decreased permeability into the bacterial cell B. Acquisition of a plasmid encoded ... the bacterial ribosome for chloramphenicol D. Switching over from ribosomal to mitochondrial protein synthesi
Last Answer : B. Acquisition of a plasmid encoded for chloramphenicol acetyl transferas
Description : Which one of the following is considered as the drug of last resort for human beings? (1) Penicillin (2) Tetracycline (3) Chloramphenicol (4) Streptomycin
Last Answer : (3) Chloramphenicol Explanation: Chloramphenicol is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis.
Description : Two cyclic polypeptide antibiotics are a. Vancomycin and streptomycin. b. Penicillin and cephalosporin. c. Bacitracin and polymyxins d. .gentamicin and chloramphenicol
Last Answer : c. Bacitracin and polymyxins
Description : Choose the antimicrobial which acts by interfering with DNA function in the bacteria: A. Chloramphenicol B. Ciprofloxacin C. Streptomycin D. Vancomycin
Last Answer : B. Ciprofloxacin
Description : All of the following statements about puromycin are true except (A) It is an alanyl tRNA analogue (B) It causes premature termination of protein synthesis (C) It inhibits protein synthesis in prokaryotes (D) It inhibits protein synthesis in eukaryotes
Description : The first amino acyl tRNA which initiates translation in prokaryotes is (A) Mehtionyl tRNA (B) Formylmethionyl tRNA (C) Tyrosinyl tRNA (D) Alanyl tRNA
Description : Which out of the following antibiotics penetrates blood-CSF barrier the best (a) Erythromycin (b) Gentamicin (c) Tetracycline (d) Chloramphenicol
Last Answer : Ans: D