Practice Questions

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

The non-template strand matches the mRNA transcript sequence exactly (except that DNA has T where RNA has U), earning it the name "coding strand."

The nucleosome is the primary structural unit of chromatin, packing a 147-base-pair segment of DNA around a histone octamer core.

Inserting or deleting a base shifts the triplet reading frame downstream, completely altering the remaining amino acid sequence.

Each phosphate group in the backbone retains a negative charge at physiological pH by releasing a hydrogen ion (H+), acting as an acid.

By convention, the coding strand is written 5' to 3' because the ribosome reads mRNA 5' to 3' to build a protein from its N- to C-terminus.

The B-DNA helix has a pitch of 3.4 nm and a base-pair step of 0.34 nm, accommodating roughly 10 base pairs per full turn.

Exons are the coding segments of a gene that remain in the mature mRNA transcript after splicing, carrying the blueprint for translation.

An N-glycosidic bond connects the 1' carbon of the pentose sugar to the nitrogen atom at position 1 in pyrimidines or position 9 in purines.

Pleiotropy happens when a single gene codes for a protein used in multiple tissues, meaning a mutation can cause widespread symptoms.