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
Last Answer : Answer : C
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 : 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 : 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 : 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 : 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 : Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin
Description : The newly entering amino acyl tRNA into A site requires (A) EF-II (B) Ribosomal RNA (C) mRNA (D) EF-I
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 : Binding of formylmehtionyl tRNA to 30 S ribosomal subunit of prokaryotes is inhibited by (A) Streptomycin (B) Chloramphenicol (C) Erythromycin (D) Mitomycin
Description : In the process of elongation of chain binding of amino acyl tRNA to the A site requires (A) A proper codon recognition (B) GTP (C) EF-II (D) GDP
Description : Ribozymes are (A) Enzymes present in ribosomes (B) Enzymes which combine the ribosomal subunits (C) Enzymes which dissociate (D) Enzymes made up of RNA
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 : Mammalian cells are not inhibited by low concentrations of tetracyclines that inhibit sensitive microorganisms because: A. Host cells lack active transport mechanism for tetracyclines B. Host cells actively pump out ... host cells has low affinity for tetracyclines D. Both A' and C' are correct
Last Answer : D. Both ‘A’ and ‘C’ are correct
Description : Lactose or its analogues act as positive regulators of lac operon by (A) Attaching to i gene and preventing its expression (B) Increasing the synthesis of catabolite gene activator protein (C) ... holoenzyme (D) Binding to repressor subunits so that the repressor cannot attach to the operator locus
Description : Insulin binding sites are present on the (A) α-subunits of insulin receptor (B) β-subunits of insulin receptor (C) γ-subunits of insulin receptor (D) α-and β−subunits of insulin receptor
Description : Which one of the following statements is not characteristic of allosteric enzymes? (A) They frequently catalyze a committed step early in a metabolic pathway (B) They are often composed of subunits (C) They follow Michaelis-Menten kinetics (D) They frequently show cooperativity for substrate binding
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 : .In the genetic dictionary, there are 64 codons as (a) 64 amino acids are to be coded (b) 64 types of tRNAs are present (c) there are 44 nonsense codons and 20 sense codons (d) genetic code is triplet.
Last Answer : (c) there are 44 nonsense codons and 20 sense codons
Description : In the genetic dictionary, there are 64 codons as (a) 64 amino acids are to be coded (b) 64 types of tRNAs are present (c) there are 44 nonsense codons and 20 sense codons (d) genetic code is triplet
Last Answer : genetic code is triplet
Description : Thyroid stimulating hormone is a dimer. The α-subunits of TSH, LH, FSH are identical. Thus the biological specificity must therefore be β subunit in which the number of amino acids is (A) 78 (B) 112 (C) 130 (D) 199
Description : The shape of an enzyme and consequently its activity can be reversibly altered from moment to moment by (A) Heat (B) Amino acid substrate (C) Allosteric subunits (D) Sulfur substitutions
Description : Erythromycin acts on ribosomes and inhibit (A) Formation of initiation complex (B) Binding of aminoacyl tRNA (C) Peptidyl transferase activity (D) Translocation
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 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 : The Shine-Dalgarno sequence is A- trailer sequence B- a stop codon C- the reading frame of a gene D- a short sequence that acts as a ribosomal binding site
Last Answer : a short sequence that acts as a ribosomal binding site
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 : 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 : The first amino acyl tRNA which initiates translation in prokaryotes is (A) Mehtionyl tRNA (B) Formylmethionyl tRNA (C) Tyrosinyl tRNA (D) Alanyl tRNA
Description : The first amino acyl tRNA which initiates translation in eukaryotes is (A) Mehtionyl tRNA (B) Formylmethionyl tRNA (C) Tyrosinyl tRNA (D) Alanyl tRNA
Description : All the following statements about charging of tRNA are correct except (A) It is catalysed by amino acyl tRNA synthetase (B) ATP is converted into ADP and Pi in this reaction (C) The enzyme recognizes the tRNA and the amino acid (D) There is a separate enzyme for each tRNA
Description : The nucleophilic attack on the esterified carboxyl group of the peptidyl-tRNA occupying the P site and the α-amino group of the new amino acyl tRNA, the number of ATP required by the amino acid on the charged tRNA is (A) Zero (B) One (C) Two (D) Four
Description : The α-amino group of the new amino acyl tRNA in the A site carries out a nucleophilic attack on the esterified carboxyl group of the peptidyl tRNA occupying the P site. This reaction is catalysed by (A) DNA polymerase (B) RNA polymerase (C) Peptidyl transferase (D) DNA ligase
Description : The enzyme amino acyl tRNA synthetase is involved in (A) Dissociation of discharged tRNA from 80S ribosome (B) Charging of tRNA with specific amino acids (C) Termination of protein synthesis (D) Nucleophilic attack on esterified carboxyl group of peptidyl tRNA
Description : Suppressor tRNAs can neutralize the effects of mutations in (A) Structural genes (B) Promoter regions (C) Enhancer elements(D) All of these
Description : The percentage of the calcium eliminated in feces is (A) 10–20 (B) 30–40 (C) 50–60 (D) 70–90
Description : The product of serum calcium concentration (mg/dl) and serum inorganic phosphorous concentration (mg/dl) in children is about (A) 30 (B) 40 (C) 50 (D) 60
Description : The product of serum calcium concentration (mg/dl) and serum inorganic phosphorous concentration (mg/dl) in adults is about (A) 30 (B) 40 (C) 50 (D) 60
Description : The total Glucose in the body is ________ gms. (A) 10–15 (B) 20–30 (C) 40–50 (D) 60–80
Last Answer : B
Description : Agonists affect the receptor molecule in the following manner: A. Alter its amino acid sequence B. Denature the receptor protein C. Alter its folding or alignment of subunits D. Induce covalent bond formation
Last Answer : C. Alter its folding or alignment of subunits
Description : The lone pair of electrons at one of the ring nitrogens in the given amino acid makes a potential ligand, which is important in binding the iron atoms in hemoglobin: (A) Tryptophan (B) Threonine (C) Histidine (D) Serine
Description : Ribosomes match up the ______ of the mRNA and the ______ of the tRNAs. a. codons; anticodons b. introns; exons c. anticodons; codons d. genes; anticodons
Last Answer : a. codons; anticodons
Description : RNA is composed of strands of nucleotides that are read as a 3 nucleotide codon. These are distinguished by tRNAs that match the codons on one end and carry individual building blocks of a protein chain. What are these building blocks of protein that tRNAs bind?
Last Answer : Amino Acids
Description : Hormone which inhibit cellular uptake and unilisation of amino acid as well as does hyperglycemia through gluconeogenesis is
Last Answer : Hormone which inhibit cellular uptake and unilisation of amino acid as well as does hyperglycemia through gluconeogenesis is
Description : The profit of a company (whose capital is divided into 25‚000 shares of Rs. 10 each) for the last three years are : Rs. 50‚000; Rs. 60‚000 and Rs. 40‚000. The fair return on investment is taken at 10% p.a. The value of company’s share will be– (A) Rs. 10 (B) Rs. 20 (C) Rs. 30 (D) Rs. 40
Last Answer : Answer: Rs. 20
Description : The irrigation water requirement of onion is (a) 60 cm (b) 50 cm (c) 40 cm (d) 30 cm
Last Answer : (c) 40 cm