Calculate the average molar concentration of a protein in a human cell

Question

Calculate the average molar concentration of a gene product (i.e. a protein) in a proliferating human cell such as a fibroblast. Assume the cell have ~5000 gene products and the average protein consists of 400 amino acids.

Please help!



Answer 1

Molar concentration is the number of moles of a substance per liter. So to answer the question, the volume of the cell and the amount of a particular gene product is needed. The number of amino acids per protein is not needed. If protein A consists of 100 amino acids, then 6.02 x 10 ²³ copies of that protein is one mole. If protein B consists of 1000 amino acids, then still 6.02 x 10 ²³ copies of that protein is one mole. The size of the protein does not matter, only the number of individual proteins.

By 5000 gene products do you mean 5000 different kinds of proteins? If that is the case, there needs to be some way of quantifying the proteins. Are you given the total mass of the proteins? If that is the case then the average amino acid content could be used to estimate the number of proteins in the cell.