The cell nucleus is the site of many important biological functions of the eukaryotic cell. These processes include transcription, replication, splicing and ribosome biogenesis.

Learn about the ultrastructure and organelles of animal, plant, fungal and bacterial cells. BBC Bitesize Scotland revision for SQA National 5 Biology.

Proteins are the workhorses of cells. Learn how their functions are based on their three-dimensional structures, ... each gene in cellular DNA contains the code for a unique protein structure.