BIO NMDCAT

Eukaryotic chromosomes are highly organized nucleoprotein complexes made of a single linear DNA molecule wound around structural histones.

A premature stop codon halts translation early, yielding an incomplete, truncated polypeptide chain that is usually non-functional.

The Watson-Crick model shows DNA as a right-handed double helix, where two complementary strands twist around a central longitudinal axis.

Enhancers are regulatory DNA sequences that bind activator proteins, interacting with the promoter to boost transcription.

The mass of a gene depends on its length; longer nucleotide sequences contain more base pairs, increasing the total molecular weight.

Thymine is a pyrimidine base specific to DNA, whereas RNA uses uracil as the complementary partner for adenine.

Each phosphate group in the phosphodiester backbone loses a hydrogen atom at cellular pH, giving the exterior of the DNA a negative charge.

The linear sequence of nucleotide codons inside exons determines the exact order of amino acids added during protein translation.

Unwinding the helix creates torsional strain and positive supercoils ahead of the moving polymerase; without topoisomerase to relieve this stress, transcription stalls.

Z-DNA is a left-handed helical variant with a zigzag sugar-phosphate backbone, favored by repeating purine-pyrimidine steps, high salt, or methylation.

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

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

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

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.

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

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