Question

List the following in the order you think they would come off the column chromatography (largest to smallest): PCR product, dNTPs, primers.  

Answer 1

In this type of column chromatography, if the size matters (Separation based on size) then the order they will come off will be - PCR product, primers, dNTPs (at last)

PCR product (generally more than 100 bp, can be up to 5-10 kb)

dNTPs - only 1 nucleotide - very small

primers - 20-50 bp

So, here the larger molecules come out of the column easily as they simply pass by the pores because those molecules are too large to enter the pores. But, smaller the molecules, more they enter into different pores and take a larger time to exit the column. PCR product, being the largest among these, will come out first. dNTPs are very small and they will enter in most of the pores and this will cause a larger path for the dNTPs to travel in the column and will take the largest time to exit.