This document summarizes key points from a lecture on molecular biology and DNA quantification: 1. It introduces molecular biology and why it is being studied, then outlines what will be covered in Biol2 including nucleic acid quantification. 2. It explains how to quantify DNA and RNA concentrations using absorbance measurements at 260nm and calculation formulas involving dilution factors and extinction coefficients. 3. It discusses potential contaminants like protein and phenol that can interfere with absorbance readings and describes using A260/A280 ratios to assess DNA purity. Examples are provided to demonstrate these quantification calculations.