The Molecular Basis Of Inheritance

The chromatin is formed of a series of repeating units called nucleosomes. Each nucleosome consists of a chain of DNA twist around a histone octamer. The core of the nucleosome consists of four histones namely HA, HB, H, and H. Another histone namely H is associated with the linker region.

Lac operon is the prototype operon in bacteria, which codes for genes (i, z, y, a) responsible for metabolism of lactose. The gene i codes for repressor, z for -galactosidase. y for permease and a for transacety lase. The repressor o f the operon is synthesised (all-the-timeconstitutivelv) from the i gene. The repressor protein binds to the operator region of the operon and prevents RNA polymerase from transcribing the operon. In the presence of an inducer, such as lactose or allolactose, the repressor is inactivated by interaction with the inducer. This allows RNA polymerase access to the promoter and transcription proceeds.

AUG act as initiator codon and UAG, UAA, UGA nonsence codon.

R-strain is rough and harmless, while S-strain is the smooth and virulent form of Streptococcuspneumoniae. In their experiment, Avery et al., found out that only when DNA from S-type bacteria is added to a culture of R-type bacteria, R-type gets converted to S-type strain. This transformation of R into S-type did not occur on addition of carbohydrate or protein from S-type bacteria. Moreover, in the first scenario, if DNase enzyme was added, i.e., Live 'R' strain + DNA from 'S' strain + DNase, the transformation would not have occurred, proving conclusively that DNA, indeed is the genetic material. Thus, the correct answer is option A.

The codon AUG has dual functions. It codes for methionine (met) and also acts as initiation codon

Answer (d) AUG-CUA-GUG-CGU-GCC

Answer (a) a -Interferon