MCQs

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.

The structural framework of the DNA strand is formed by a repeating chain of deoxyribose sugars linked by neutral phosphodiester groups.

Silent mutations take advantage of the redundancy of the genetic code, where multiple codons translate into the same amino acid.

Each G-C pair has three hydrogen bonds (5×3=15) and each A-T pair has two (3×2=6). The total is 15+6=21.

Alleles are alternative nucleotide variants of a gene found at the same chromosomal locus, governing variations of the same trait.

To form proper hydrogen bonds across the core, the twin strands must line up in opposite orientations, pairing a 5' end with a 3' end.

A locus refers to the fixed geographic coordinate or position where a gene or genetic marker resides on a chromosome.

Coined by Francis Crick, the Central Dogma outlines the unidirectional transfer of functional sequence information during gene expression.

Lacking a 2'-OH group allows deoxyribose to prefer a C2'-endo sugar pucker, which drives the flexible, uncrowded B-DNA geometry.

An operon is a functional genetic unit found in bacteria that allows several genes in a shared pathway to be transcribed together as a single mRNA.

Heating a DNA sample provides enough thermal energy to break the hydrogen bonds and base-stacking interactions, separating the strands.

A nonsense mutation introduces a premature stop signal (UAA, UAG, or UGA), halting translation and yielding a truncated protein.

The flat base pairs stack horizontally inside the core of the helix, resembling the sequential steps of a spiral staircase.