Question

Many important experiments require that DNA be denatured. What happens when DNA is denatured by heat?

a. the hydrogen bonds between nitrogen bases are broken.
b. the bonds between the 5' carbon and the phosphate group are broken.
c. bonds between the 3' carbon and the previous nucleotide are broken.
d. the mRNA binds to the DNA template.

Answer 1

When DNA is denatured by heat, the hydrogen bonds between nitrogen bases are broken, leading to the separation of the two DNA strands. This separation is necessary for many biotechnological experiments and the process is reversible upon cooling or removal of denaturing agents.

Step-by-step explanation:

When DNA is denatured by heat, the hydrogen bonds between nitrogen bases are broken. This process leads to the separation of the double-stranded DNA (dsDNA) into two single-stranded DNA (ssDNA). The denaturation occurs when DNA is subjected to high temperatures, typically above 80 to 90 degrees Celsius, which can disrupt hydrogen bonds as well as hydrophobic interactions between the bases, resulting in the two strands unwinding and separating. The temperature at which 50% of a DNA sample is denatured is referred to as its melting temperature (TM), which varies depending on the DNA's GC content: higher GC content leads to a higher TM. Upon cooling or removal of denaturing agents, the two strands can reanneal as hydrogen bonds reform, a process which is essential in various biotechnological applications.