To sort the DNA strands in a tube, you can use gel electrophoresis. This process involves loading the DNA samples onto a gel matrix, applying an electric field to the gel, and allowing the negatively charged DNA molecules to migrate towards the positive electrode. The DNA fragments will separate based on their size, with smaller fragments migrating farther down the gel than larger fragments. By comparing the migration of the unknown DNA sample to known DNA standards of various sizes, you can determine the size of the fragments in the unknown sample.
To measure the amount of DNA in the tube, you can use a spectrophotometer to measure the absorbance of light by the DNA molecules at a specific wavelength. DNA absorbs light strongly at 260 nm, so by measuring the absorbance at this wavelength, you can determine the concentration of DNA in the sample. Additionally, by measuring the ratio of absorbance at 260 nm to 280 nm, you can assess the purity of the DNA sample, as impurities such as proteins and phenol will absorb light at 280 nm.