The following statements are made with respect to merodiploids of the lac operon, where “I” is the lac repressor, “O” is the lac operator, “Z” is the lacZ gene encoding […]
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Ribosome Recycling in Bacteria: The Essential Roles of RRF and EF-G
For continuation of protein synthesis in bacteria, ribosome need to be released from the mRNA as well as to dissociate into subunits. These processes do not occur spontaneously. They need […]
Phenotype of E. coli I– O+ Z+ Y– / F’ I+ OC Z– Y+ Merodiploid: Constitutive or Inducible?
20. With reference to lac operon, what will be the phenotype of an E. coli strain having a genotype I– O+ Z+ Y– /F’ I+ OC Z– Y+ ? (1) […]
Translation Initiation Factor IF3: The Anti-Association Factor for 30S and 50S Ribosomal
Which one of the following translation factors is used at the step Of translation initiation and defined as anti- association factor for 30S and 50S subunit interactions? (1) IF1 (2) […]
LacZ Expression in E. coli Detection by X-gal, ONPG, and MacConkey Agar
19. Which one of the following statements relating to the mechanism of color development in response to LacZ expression in Escherichia coli is INCORRECT? (1) E. coli growth on LB […]
Understanding lacY Mutants in E. coli: β-Galactosidase Synthesis and Lactose Permease Function
Mutants of lac Y (Y–) gene of E. coli do not synthesize the lactose permease protein. The following statements refer to the behaviour of lac mutants under different experimental conditions. […]
How Internal Ribosomal Entry Sites Promote Translation Under Stress
Presence of an internal ribosomal entry site (IRES) in mRNA (1) Inhibit its translation (2) promotes its post transcriptional processing (3) has no impact on its translation (4) promotes its […]
β-Galactosidase Expression in lac Operon Mutants and Merodiploid E. coli: Understanding OCI+Z– and O+I–Z+ Genotypes
In context to lac operon. if two bacterial strains P1 and P2 with the genotypes OCI+Z– and O+I–Z+ respectively, were used to produce mero-diploid daughter strain D, which one of […]
Decoding E. coli Growth Curves: Glucose, Galactose, and Phage Infection Dynamics
16. E.coli was grown in three different experimental conditions. In one, it was grown in medium Containing as carbon source; in the second in medium containing both glucose and galactose; […]
Lac Repressor vs. Pur Repressor: Key Differences in Gene Regulatory Mechanisms
15. Lac repressor inhibits expression of genes lac-operon whereas purine biosynthesis is repressed by the Pur repressor. The two sequences and have Similar three dimensional The gene regulatory properties of […]


