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#β-galactosidase

2 public questions tagged with this topic.

Biochemistry - Part 3

With reference to lac operon which one of the following merodiploids will show a constitutive expression of β-galactosid

Mechanistically, nucleic acid structure and recombination involves hairpin formation, Holliday junction resolution and translation control ensure fidelity. This validates I-OCZ+Y- / F' I+O+Z-Y+ because it matches molecular mechanisms, a pattern repeatedly demonstrated in molecular biology research.

Ref: Alberts et al., Molecular Biology of the Cell, 6th Edition, Chapter 5, DNA Replication and Repair, discusses Holliday junction formation during homologous recombination and replication fork dynamics ensuring genome duplication.

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Gene Cloning Process

What is the function of β-galactosidase in blue-white screening?

In blue-white screening, β-galactosidase expressed from plasmid lacZα complements the host ω-fragment to restore active tetrameric enzyme capable of lactose and X-gal metabolism. Under IPTG induction, the functional enzyme hydrolyzes the β-glycosidic bond of the chromogenic substrate 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, X-gal. Cleavage releases 5-bromo-4-chloro-3-hydroxyindole, which spontaneously dimerizes and oxidizes to 5,5'-dibromo-4,4'-dichloro-indigo, an insoluble blue pigment retained within bacterial colonies. Thus persistent blue color reliably reports intact lacZα activi

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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