Description : Transcription of structural genes of lac operon is prevented by binding of the repressor tetramer to (A) i gene (B) Operator locus (C) Promoter (D) z gene
Last Answer : Answer : B
Description : Expression of structural genes of lac operon is affected by all the following except (A) Lactose or its analogues (B) Repressor tetramer (C) cAMP (D) CAP-cAMP complex
Last Answer : Answer : C
Description : Lac operon is a cluster of (A) Three structural genes (B) Three structural genes and their promoter (C) A regulatory gene, an operator and a promoter (D) A regulatory gene, an operator, a promoter and three structural genes
Last Answer : Answer : D
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 : .The lac operon consists of (a) four regulatory genes only (b) one regulatory gene and three structural genes (c) two regulatory genes and two structural genes (d) three regulatory genes and three structural genes.
Last Answer : (b) one regulatory gene and three structural genes
Description : Match the following genes of the Lac operon with their respective products. (A) i gene (i) b-galactosidase (B) z gene (ii) Permease (C) a gene (iii)Repressor (D) y gene (iv) Transacetylase Select the correct option. (A) (B) (C) ( ... ) (iii) (ii) (iv) (c) (iii) (i) (ii) (iv) (d) (iii) (i) (iv) (ii)
Last Answer : (a) (iii) (iv) (i) (ii)
Last Answer : d) (iii) (i) (iv) (ii)
Description : .Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition ... be induced by lactose (d) negative and inducible because repressor protein prevents transcription.
Last Answer : (d) negative and inducible because repressor protein prevents transcription.
Description : Gene regulation governing lactose operon of E.coli that involves the lac I gene product is (a) negative and repressible because repressor protein prevents transcription (b) feedback inhibition ... be induced by lactose (d) negative and inducible because repressor protein prevents transcription.
Description : The function of a repressor protein in an operon system is to prevent synthesis by binding to (A) The ribosome (B) A specific region of the operon preventing transcription of structural genes (C) The RNA polymerase (D) A specific region of the mRNA preventing translation to protein
Description : .E.coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of energy because (a) the lac operon is constitutively active in these cells ( ... coli cells do not utilise lactose (d) they cannot transport lactose from the medium into the cell.
Last Answer : (b) they cannot synthesise functional beta galactosidase
Description : Select the incorrect statement out of the five given below about lac operon when Lactose is present in the medium. a) Gene - A gets transcribed into mRNA which produces β-galactoside permease b) ... polymerase transcribe Z-gene, Y-gene and A-gene e) Allolactose is the inducer of lac operon
Last Answer : Gene – A gets transcribed into mRNA which produces β-galactoside permease b) Inducer-Repressor complex is formed
Description : Trancription of z, y and a genes of lac operon is prevented by (A) Lactose (B) Allo-lactose (C) Repressor (D) cAMP
Description : Which of the following genes of the E.coli “Lac operon” codes for a constitutive protein? (A) The ‘a’ gene (B) The ‘i’ gene (C) The ‘c’ gene (D) The ‘z’ gene
Description : The enzymes encoded by z, y and a genes of lac operon are inducible, and their inducer is (A) Lactose (B) Allo-lactose (C) Catabolite gene activator protein (D) All of these
Description : Which one of the following is NOT part of an operon? a. Regulatory gene b. Operator c. Promoter d. Structural genes
Last Answer : d. Structural genes
Description : Which one of the following is wrongly matched? (a) Transcription - Writing information from DNA to tRNA. (b) Translation - Using information in mRNA to make protein. (c) Repressor protein - Binds to operator to stop enzyme synthesis. (d) Operon - Structural genes, operator and promoter.
Last Answer : (c) Repressor protein - Binds to operator to stop enzyme synthesis.
Last Answer : (d) Operon - Structural genes, operator and promoter
Description : In the ’lac operon’ concept, which of the following is a protein? (A) Operator (B) Repressor (C) Inducer (D) Vector
Description : In the lac operon concept, a protein molecule is (A) Operator (B) Inducer (C) Promoter (D) Repressor
Description : Select the two correct statements out of the four (i - iv) statements given below about lac operon. (i) Glucose or galactose may bind with the repressor and inactivate it. (ii) In the absence of lactose, the repressor binds with the ... (iii) (b) (i) and (iii) (c) (ii) and (iv) (d) (i) and (ii)
Last Answer : (c) (ii) and (iv)
Description : Lac operon of E. coli contains _______ is continuity. (A) Regulator and operator genes only (B) Operator and structural genes only (C) Regular and structural genes only (D) Regulator, operator and structural genes
Description : The coding sequences in lac operon include (A) i gene (B) i gene, operator locus and promoter (C) z, y and a genes (D) i, z, y and a genes
Description : The region of the Lac operon which must be free from structural gene transcription to occur is (A) The operator locus (B) The promoter site (C) The ‘a’ gene (D) The ‘i’ gene
Last Answer : Answer : A
Description : In Lac-operon, repressor protein binds to
Last Answer : In Lac-operon, repressor protein binds to A. Regulator gene B. Operator gene C. Promoter gene D. Structural gene
Description : The gene of lac operon which has constitutive expression is (A) i (B) c (C) z (D) p
Description : The structural genes of lac operon transcribe mRNA which is a) polycistronic b) replicative c) monokaryotic d) monocistronic
Last Answer : a) polycistronic
Description : Silencer elements (A) Are trans-acting factors (B) Are present between promoters and the structural genes (C) Decrease the expression of some structural genes (D) Encode specific repressor proteins
Description : Binding of RNA polymerase holoenzyme to the promoter region of lac operon is facilitated by (A) Catabolite gene activator protein (CAP) (B) cAMP (C) CAP-cAMP complex (D) None of these
Description : Mutations in promoter regions of genes can cause (A) Premature termination of translation (B) Change in reading frame of downstream structural gene (C) Decreased efficiency of transcription (D) All of these
Description : .In negative operon, (a) co-repressor binds with repressor (b) co-repressor does not bind with repressor (c) co-repressor binds with inducer (d) cAMP have negative effect on lac operon. (
Last Answer : co-repressor binds with repressor
Description : The smallest unit of DNA capable of coding for the synthesis of a polypeptide is (A) Operon (B) Repressor gene (C) Cistron (D) Replicon
Description : Lac operon is a cluster of genes present in (A) Human beings (B) E. coli (C) Lambda phage (D) All of these
Description : RNA polymerase holoenzyme binds to lac operon at the following site: (A) i gene (B) z gene (C) Operator locus (D) Promoter region
Description : Positive control of induction is best described as a control system in which an operon functions (A) Unless it is switched off by a derepressed repressor protein (B) Only after a repressor protein is ... on (D) Only after an inducer protein, which is activated by an inducer, switch it on
Description : In operon concept, regulator gene functions as (a) inhibitor (b) repressor (c) regulator (d) all of these.
Last Answer : a) inhibitor
Description : What genes are parts of the lac operon? -Biology
Last Answer : answer:
Description : The lac operon is an example of (a) repressible operon (b) overlapping genes (c) arabinose operon (d) inducible operon.
Last Answer : (d) inducible operon.
Description : An example of an inducible group of genes is the ______. a. ARG operon b. NAC operon c. LAC operon d. SAC operon
Last Answer : c. LAC operon
Description : Besides structural genes that encode proteins, DNA contains some regulatory sequences which are known as (A) Operons (B) Cistrons (C) Cis-acting elements (D) Trans-acting factors
Description : Lac operon’ in E. coli, is induced by (a) ‘I’ gene (b) promoter gene (c) β-galactosidase (d) lactose.
Last Answer : (c) β-galactosidase
Description : To commence structural gene transcription the region which should be free on lac operation is (A) Promoter site (B) Operator locus (C) Y gene (D) A gene
Description : Which of the following is required as inducer(s) for the expression of Lac operon? (a) Lactose (b) Lactose and galactose (c) Glucose (d) Galactose
Last Answer : (c) Glucose
Last Answer : Lactose
Description : When does the lac repressor protein bind to the operator? -Biology
Description : The ribosome binding site A- forms a stem-loop structure in the RNA B- is located upstream of the promoter sequence C- .is located immediately upstream of the start codon D- is more likely to be associated with an operon than with a gene encoding a single protein
Last Answer : .is located immediately upstream of the start codon
Description : The rivosome binding site A- forms a sltem- loop structure in the RNA B- is located upstream of the promoter sequence C- is located immediately upstream of the start codon D- is more likely to be associated with an operon than with a gene encoding a single protein
Last Answer : is located immediately upstream of the start codon
Description : In E. coli, during lactose metabolism repressor binds to (a) regulator gene (b) operator gene (c) structural gene (d) promoter gen
Last Answer : (b) operator gene
Description : .All of the following are part of an operon except (a) an operator (b) structural genes (c) an enhancer (d) a promoter.
Last Answer : d) a promoter.