MCQs

Having fewer hydrogen bonds makes A-T rich regions easier to unzip, which is why replication origins and promoters are rich in A-T pairs.

B-DNA is the standard, stable conformation adopted by native DNA molecules inside the aqueous environment of living cells.

A cistron is a genetic unit defined by the cis-trans position test, matching the DNA sequence needed to build one polypeptide.

The wider, deeper gap on the outside of the helix is the major groove, which provides easy access for sequence-specific DNA-binding proteins.

DNA methyltransferases add a methyl group to the carbon-5 position of cytosine rings, a key modification for silencing gene expression.

Without a functional promoter sequence, RNA polymerase cannot locate or bind the gene, shutting down transcription entirely.

Enclosing the genetic bases within the hydrophobic core protects the fragile hereditary codes from reactive molecules in the cytoplasm.

By showing that viral DNA (32P) enters the host cell while viral protein (35S) stays outside, they proved DNA is the hereditary material.

The template strand runs anti-parallel and complementary to the coding strand, making the matching sequence 3'-TACGTT-5'.

The spliceosome is a large ribonucleoprotein complex that removes introns and splices exons together to form mature mRNA.

The total cross-sectional width of the standard B-form DNA double helix is 2.0 nm (20 A˚).

With 61 codons coding for 20 amino acids, most amino acids are specified by more than one triplet codon, making the code degenerate.

A gene includes its structural coding sequence alongside the regulatory elements required to turn its expression on or off.

RNA polymerase tracks along the DNA template strand to assemble ribonucleoside triphosphates into a complementary RNA molecule.

Pairing purines with pyrimidines preserves a constant 2 nm spacing, preventing structural bulges or pinches along the helix.

The genome encompasses the total collective repository of an organism's hereditary instructions stored within its nucleic acids.

A full 360∘ turn accommodates roughly 10 base pairs, meaning each step rotates the helix by an angle of approximately 36∘.

DNA replication is the semi-conservative duplication of the cellular genome, ensuring each daughter cell inherits a complete set of genes.

The TATA box is a critical promoter element situated upstream of the transcription start site, helping position RNA polymerase II.