Question

The mouse genome G+C content is 42%. What is the T_m of mouse genomic DNA in 0.1 M NaCl?

Answer 1

• G+C percentage (% G+C) refers to: The percent content of Guanine and Cytosine (G+C), in nucleic acid (DNA, RNA), in comparison to total nitrogenous bases (Adenine, Cytosine, Guanine, Thymine /Uracil).
• G+C content is due to higher stability of G and C bonding, due to presence of triple bond.
• Thus, the denaturation temperature required to separate strands, will determine whether the sample has poor GC content or higher GC content, called the melting or denaturation temperature (Tm).

For DNA:

T_m = 16.6 log[Na⁺] + 0.41 (% G+C) + 81.5

Given:

• (% G+C) = 42
• [Na⁺] = 0.1 M

T_m = 16.6 log 0.1 + 0.41 (42) + 81.5

T_m = 16.6 x(-1) + 98.72

T_m = 82.12