Question

What would be the molar concentration of human DNA in a human cell? Consult your teacher.

Answer 1

Human DNA has $3.3\times 10{}^9$ base pairs.

Avogadro number of molecules is one mole. The next step is converting the amount of DNA into moles. Now in Human DNA, $3.3\times 10{}^9$ base pairs of nucleotides are present.

So number of moles =$3.3\times 10{}^9$ / Avagadro number

= $3.3\times 10{}^9$ / $6.03\times 10{}^{23}$

= $3.3\times 10{}^9$ * $1.66\times {10}^{-24}$

= $5.5\times {10}^{-15}$ moles or 5.5 femtomoles.

molarity is defined as the number of moles of solute per liter of solution

therefore, the molar concentration of human DNA can be calculated by knowing the volume of water/liquid in the cell. The volume varies in different cells. The average volume is 5 picoliter or $5.\times {10}^{-12}$

So, molarity = $5.5\times {10}^{-15}$ / $5.\times {10}^{-12}$ = $1.1\times {10}^{-3}$ M.

or 0.0011M or 1.1 mM.