Structure of DNA

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

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

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

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

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

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.

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

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

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

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

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

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

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

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

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.

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

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

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

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.