What is GO?

The Gene Ontology (GO) is a dynamic, controlled vocabulary consisting of three interrelated ontologies that describe: biological processes, molecular functions and cellular components of a normal cell. These ontologies are organised hierarchically, with terms connected by various relationships (see Figure 1).

The Three Ontologies of GO (see Figure 2):

• Biological Process: Represents a series of molecular events or functions. Processes span all levels, from subcellular metabolic pathways to tissue- and organ-level events, and even organism-level processes such as behavior and inter-organism interactions.
• Molecular Function: Describes the activities of individual gene products at the molecular level, such as catalyzing chemical reactions or binding specific chemicals or macromolecules.
• Cellular Component: Refers to the parts of a cell, including subcellular structures, macromolecular complexes, and the extracellular environment where gene products are located (e.g., cytoplasm, ribosome, or translation release factor complex).

GO terms do not directly describe gene products but instead describe the activities they perform and their locations. To understand a gene product, you combine annotations describing its components, processes, and functions. For example, the ontology does not include “cytochrome” but contains terms describing the functions of cytochromes, such as “electron carrier activity.”

Why do we need GO?

Biologists often use specialised language filled with acronyms, jargon, and repurposed common terms, which can confuse both non-scientists and scientists. This complexity is further exacerbated by:

• Organism-specific meanings of terms (e.g., “budding” means one thing for plants and another for yeast).
• Different phrases referring to the same phenomenon.
• Subtle differences in terminology, which can hinder communication and complicate automated data sharing.

The Gene Ontology (GO) project addresses these challenges by providing consistent, standardised descriptions of gene products (proteins and RNA), facilitating better communication and enabling seamless data exchange within the scientific community.