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
Last Answer : Answer : A
Description : Which of the following step of translation does not consume a high energy phosphate bond? (a) Peptidyl transferase reaction (b) Aminoacyl tRNA binding to A-site (c) Translocation (d) Amino acid activation
Last Answer : (b) Aminoacyl tRNA binding to A-site
Last Answer : (a) Peptidyl transferase reaction
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 : Erythromycin acts on ribosomes and inhibit (A) Formation of initiation complex (B) Binding of aminoacyl tRNA (C) Peptidyl transferase activity (D) Translocation
Last Answer : Answer : D
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 newly entering amino acyl tRNA into A site requires (A) EF-II (B) Ribosomal RNA (C) mRNA (D) EF-I
Description : After formation of a peptide bond, mRNA is translocated along the ribosome by (A) eEF-1 and GTP (B) eEF-2 and GTP (C) Peptidyl transferase and GTP (D) Peptidyl transferase and ATP
Last Answer : Answer : B
Description : Streptomycin prevents synthesis of polypeptide by (A) Inhibiting initiation process (B) Releasing premature polypeptide (C) Inhibiting peptidyl transferase activity (D) Inhibiting translocation
Description : Peptidyl transferase activity is present in (A) 40 S ribosomal subunit (B) 60 S ribosomal subunit (C) eEF-2 (D) Amino acyl tRNA
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 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 : Elongation of a peptide chain involves all the following except (A) mRNA (B) GTP (C) Formyl-Met-tRNA (D) Tu, TS and G factors
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 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 : 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 : G-proteins have a nucleotide binding site for (A) ADP/ATP (B) GDP/GTP (C) CDP/CTP (D) UDP/UTP
Description : Peptidyl transferase activity of 50 S ribosomal subunits is inhibited by (A) Rifampicin (B) Cycloheximide (C) Chloramphenicol (D) Erythromycin
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 : 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 : 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 : GTP is not required for (A) Capping L of mRNA (B) Fusion of 40S and 60S of ribosome (C) Accommodation of tRNA amino acid (D) Formation of tRNA amino acid complex
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 : Which of the following molecule catalyzes the transpeptidation reaction? A.RNA polymerase B.Peptidyl transferase C.DNA ligase D.DNA polymerase
Last Answer : B.Peptidyl transferase
Description : Peptidyl transferase a) Is a 23s rRNA b) forms peptide bonds c) component of ribosome d) all the three
Last Answer : d) all the three
Description : Initiation of protein synthesis requires (A) ATP (B) AMP (C) GDP (D) GTP
Description : The cofactors required for synthesis of adenylosuccinate are (A) ATP, Mg++ (B) ADP (C) GTP, Mg++ (D) GDP
Description : Adenylate cyclase is activated by (A) GDP-bearing α-Subunit of G-protein (B) GTP-bearing α-Subunit of G-protein (C) GDP-bearing γ-Subunit of G-protein (D) GTP-bearing γ-Subunit of G-protein
Description : Coenzyme for phosphoenolpyruvate carboxykinase is (A) ATP (B) ADP (C) GTP (D) GDP
Description : Allsoteric activator of glutamate dehydrogenase is (A) ATP (B) GTP (C) ADP and GDP (D) AMP and GMP
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 : Newly synthesized tRNA undergoes posttranscriptional modifications which include all the following except (A) Reduction in size (B) Methylation of some bases (C) Formation of pseudouridine (D) Addition of C-C-A terminus at 5’ end
Description : The following are true about G proteins: a. they are first messengers b. when activated, the alpha subunit exchange GDP for GTP c. they are transmembrane signal receptor molecules d. vibrio cholerae secrets an exotoxin which makes G-proteins resistant to inactivation
Last Answer : when activated, the alpha subunit exchange GDP for GTP
Description : During phototransduction: a. hyperpolarisation occurs due to closure of the sodium channels b. 11-cis-retinal molecules are converted to all-trans-retinal c. transducin, a G protein converts GDP to GTP d. all above
Last Answer : all above
Description : Acetyl-CoA is the principal building block of fatty acids. It is produced within the mitochondria and does not diffuse readily into cytosol. The availability of acetyl CoA involves (A) Carnitine acyl transferase (B) Pyruvate dehydrogenase (C) Citrate lyase (D) Thiolase
Description : The semialdehydes are formed under the action of enzymes characterised as (A) Aldolases (B) Peptidyl lysyl oxidases (C) Collagenases (D) Elastases
Description : Synthesis of polyunsaturated fatty acids involves the enzyme systems: (A) Acyl transferase and hydratase (B) Desaturase and elongase (C) Ketoacyl-CoA reductase and hydratase (D) Dihydroxyacetone phosphate
Description : The pathway of glycogen biosynthesis involves a special nucleotide of glucose. In the reaction below, NuDP stands for NuDP Glucose + glycogenn → NuDP + glycogenn+1 (A) ADP (B) GDP (C) UDP (D) CDP
Description : UDP and UTP are formed by phosphorylation from (A) AMP (B) ADP (C) ATP (D) GTP
Description : The formation of initiation complex during protein synthesis requires a factor: (A) IF-III (B) EF-I (C) EF-II (D) IF-I
Description : Site in the ribosome from which the tRNA donates amino acids to the growing polypeptide chain is A- P site B- O site C- T site D- A site
Last Answer : P site
Description : Orotic aciduria type II reflects the deficiency of the enzyme: (A) Orotate phosphoribosyl transferase (B) Orotidylate decarboxylase (C) Dihydroorotase (D) Dihydroorotate dehydrogenase
Description : Bilirubin UDP-glucuronyl transferase is absent from liver in (A) Crigler-Najjar syndrome, type I (B) Gilbert’s disease (C) Crigler-Najjar syndrome, type II (D) Rotor’s syndrome
Description : Apolipoprotein C-II is an activator of (A) Lecithin cholesterola acyl transferase (B) Phospholipase C (C) Extrahepatic lipoprotein lipase (D) Hepatic lipoprotein lipase
Description : Okazaki pieces are formed during the synthesis of (A) mRNA (B) tRNA (C) rRNA (D) DNA
Description : l,m and n are three parallel lines intersected by transversal p and q such that l,m and n cut-off equal intersepts AB and BC on p (Fig.8.55). Show that l,m and n cut - off equal intercepts DE and EF on q also. -Maths 9th
Last Answer : Given:l∥m∥n l,m and n cut off equal intercepts AB and BC on p So,AB=BC To prove:l,m and n cut off equal intercepts DE and EF on q i.e.,DE=EF Proof:In △ACF, B is the mid-point of ... a triangle, parallel to another side, bisects the third side. Since E is the mid-point of DF DE=EF Hence proved.
Description : ATP is required for (A) Fusion of 40S and 60S of ribosome (B) Accommodation tRNA amino acid in a site of ribosome (C) Movement of ribosome along mRNA (D) formation of tRNA amino acid complex
Description : AUG, the only identified codon for methionine is important as (A) A releasing factor for peptide chains (B) A chain terminating codon (C) Recognition site on tRNA (D) A chain initiating codon