‘Bridges’ is not a common term in biology, but depending on the possible context, it can mean several things: 

Molecular Scaffold 

In cell signalling or the assembly of enzyme complexes, certain proteins (e.g. Scaffold Proteins) act as ‘bridges’ to help other molecules bind in an orderly manner to improve the efficiency of the reaction. Molecular Scaffold In cell signalling or the assembly of enzyme complexes, certain proteins (e.g. Scaffold Proteins) act as ‘bridges’ to help other molecules bind in an orderly manner and to improve the efficiency of the reaction.

Example: Scaffold proteins (e.g. KSR) in the MAPK signalling pathway ensure that the kinase cascade is carried out accurately.

Synaptic ‘bridges’ 

Between neurons, scaffolding proteins (e.g. PSD-95) in the post-synaptic dense zone (PSD) act as ‘bridges’, anchoring receptors (e.g. NMDA receptors) and signalling molecules to maintain synaptic plasticity.

Organic Matrices in Biomineralisation 

Organic matrices, such as collagen, act as ‘bridges’ to guide the orderly deposition of minerals (e.g., hydroxyapatite) during the formation of bones and shells.

Artificial scaffolds for synthetic biology 

Artificially engineered DNA or protein scaffolds allow for the targeted assembly of enzyme complexes to improve the efficiency of metabolic pathways (e.g. biofuel production).