A microtubule-associated molecular motor that generally transports cargo toward minus ends.

The H3+ ion. Two electrons occupy a fully bonding three-centre orbital at a triangular geometry; the filled nondegenerate shell differs from the open degenerate shell of neutral ground-state H3.

In octahedral molecular geometry, six donor directions point toward the vertices of an octahedron. Three mutually cis donors can occupy one face; three coplanar donor directions can occupy a meridian.

In square planar molecular geometry, four donor atoms surround a center in a plane. Two matching ligands can be cis or trans. Low-spin $d^8$ complexes of many late transition metals commonly have this geometry.

Square-pyramidal molecular geometry has four basal donor positions in a square and one axial donor. Removing one axial ligand from an octahedral molecular geometry lowers orbitals with $z$ character. A common $d$-level order is $d_{x^2-y^2}>d_{z^2}>d_{xy}>d_{xz}=d_{yz}$, although the middle pair depends on axial strength and distances.

A ring fusion shares two neighboring atoms and their bond between rings. Cis or trans fusion specifies the relative faces of junction substituents; axial/equatorial labels additionally require a conformation.

A molecular geometry in which three attached chemical atoms and their central atom lie in one plane. The ideal symmetric arrangement has three $120^{\circ }$ angles and D3h molecular point group symmetry, as in an isolated boron trifluoride molecule.

A five-coordinate geometry with two axial sites and three equatorial sites. Ideal axial–equatorial and equatorial–equatorial angles are $90^{\circ }$ and $120^{\circ }$.

A molecular framework in which two rings share exactly one atom.

A connected molecular framework described by a polyhedral vertex graph. Terminal ligands are distinguished from atoms belonging to the skeletal framework.

Interconversion of molecular arrangements that exchanges chemically distinguishable sites. In NMR spectroscopy, exchange fast compared with the relevant frequency difference can merge signals, so observed equivalence need not be a static molecular symmetry.

The complex of DNA and associated proteins that organises nuclear genetic material and helps regulate its accessibility.

Measurement of RNA profiles in individual cells. It resolves heterogeneous biological populations, but transcript abundance alone does not prove lineage potential, signalling dependence or new transcription.

Covalent methyl-group modification of DNA, involved in regulation and cellular memory. Its relationship to transcription depends on genomic location and biological context.

Creation of an additional inherited copy of a gene. Copies can be lost, retain shared functions, undergo subfunctionalization, or undergo neofunctionalization; duplication alone does not guarantee a useful novelty.

Partitioning of ancestral functions or expression domains between duplicated genes. Each copy can retain a subset of deployments that a single ancestral copy performed.

Acquisition of a new function by a gene copy, classically following gene duplication. The other copy can retain an ancestral function while changes accumulate in the retained duplicate.

Origin of a new coding gene from ancestrally non-coding DNA, rather than divergence from a previously coding copy. Failure to detect a distant relative is insufficient evidence: comparative genomic context and evidence of ancestral coding status matter.

site-directed mutagenesis deliberately changes a specified sequence position. Functional interpretation requires distinguishing a local mechanistic effect from altered abundance, localization or protein folding.

Genetic engineering deliberately modifies genetic material or its operation. It includes introducing a sequence, removing a gene or changing regulation with targeted molecular tools. A gene knockout tests consequences of losing functional output, while a modified regulatory sequence can change timing or tissue specificity. Interpretation requires verifying the resulting sequence and expression: delivery of a construct alone does not establish the intended genetic or phenotypic change. ^[ref]