Molecular Biology

Statement I: In the lac operon, the z gene does indeed code for β-galactosidase, the enzyme that hydrolyzes lactose into galactose and glucose. This statement is true.
Statement II: The lac operon is induced by the presence of lactose (or allolactose, a lactose isomer). The presence of glucose actually represses the lac operon, even if lactose is present. This phenomenon is called catabolite repression. Galactose doesn’t directly induce the lac operon; it’s the presence of lactose that matters. Therefore, statement II is false.

The correct sequence of steps in PCR is: C. Denaturation A. Annealing D. Treatment with Taq polymerase and deoxynucleotides E. Extension B. Amplification ( 1 billion times)
Thus, C → A → D → E → B

Statement I: RNA interference (RNAi) is a mechanism found in many eukaryotic organisms that is used as a cellular defense mechanism against viruses and other foreign genetic material. It also plays a role in regulating gene expression. Thus, Statement I is true.
Statement II: RNAi involves the silencing of mRNA by double-stranded RNA (dsRNA), not single-stranded RNA (ssRNA). The dsRNA is processed into small interfering RNAs (siRNAs), which then guide the RNA-induced silencing complex (RISC) to the target mRNA. The RISC cleaves the target mRNA, leading to its degradation and preventing translation.
Thus, statement II is false.

EcoRI is a restriction endonuclease that recognizes the palindromic sequence GAATTC and cuts the DNA between G and A, producing sticky ends.
It does not produce blunt ends or act as an exonuclease.