Chemical Competent Cell Preparation (E. coli): Calcium chloride method to render E. coli chemically competent for plasmid uptake.

Heat‑Shock Transformation: Facilitates plasmid DNA entry into CaCl2‑treated E. coli via heat shock.

Bacteriophage Adsorption/Transduction: Calcium ions enhance adsorption of phages (e.g., P1, T4) to E. coli for efficient transduction.

Calcium Phosphate Transfection: Used to form DNA–calcium phosphate precipitates for mammalian cell transfection.

Enzyme Assays (Ca2+ Cofactor/Stabilizer): Supplies Ca2+ to activate or stabilize enzymes such as nucleases (e.g., DNase I) and select proteases.

Alginate Gelation/Encapsulation: Crosslinks sodium alginate to form hydrogels or beads for cell encapsulation and biomaterials.

Media and Buffer Supplementation: Adjusts calcium levels in cell culture media and prepares buffers/saline requiring Ca2+ (e.g., PBS with Ca2+/Mg2+).

Protein and Cell Adhesion Studies: Provides Ca2+ to support cadherin-mediated adhesion and calcium-dependent signaling experiments.