BIO370Y5 Study Guide - Midterm Guide: Periplasm
Document Summary
Clear picture of the interior of a living cell shows average distribution of molecules at proper scale, the proper concentration with no missing parts. Electron microscopy gives a view that is too coarse: subcellular structures are studied, but indv molecules are not seen. X-ray crystallography and classical biochemistry are too fine: indv molecules studied in detail but info on their cellular environment is lost in purification. The intermediate level-the molecular structure of cells-must be synthesized from the info from these 2 extremes to form a realistic overall view. Drawing attempted to combine molecular composition data with structural results for e. coli. The typical cell is an e. coli strain b/r in balanced growth at 37 c in glucose minimal medium. Periplasmic space is bigger than space between 2 membranes. Partitioning of proteins between diff portions of the cell is the major difficulty in the synthesis of illustrations. Protein comprises 55% of the dry weight of the cell.
