Cell counting in suspension

Content
Mutations : 2.  Biochemical Level (Biochemical and Microbial Genetics)
Inborn errors of metabolism in man
Eye transplantation in Drosophila
Biochemical mutations in Neurospora
Mutations in E. coli for resistance against phages or antibiotics
Cell counting in suspension
Calculation of mutation rates and frequencies
Biochemical mutations and biosynthetic pathways
Gene sequences and enzyme sequences in biosynthetic pathways
In mutation studies, since a known number of cells need to be plated for calculating mutation rates, it is necessary to count cells per unit volume (per ml). This can be achieved by any of the following methods : (i) A hemocytometer may be placed under the microscope and the cells may be counted on a marked grid, (ii) A calibration curve using different levels of turbidity (with known counts of cells) can be drawn (turbidity measured as light passing through the suspension). Then for samples with unknown counts, turbidity may be measured and corresponding counts may be determined from turbidity curve, (iii) Suspensions of known dilution are plated on solid medium and colonies are counted (each colony derived from a single cell). (iv) Electronic cell counters may be used.