Question

Which of the following is not true regarding the denaturation and reannealing of double-stranded DNA molecules? Which of the following is not true regarding the denaturation and reannealing of double-stranded DNA molecules? Decreasing the salt concentration of the solution lowers DNA's melting point (Tm). Increasing the G-C content of DNA raises its melting point (Tm). Single-stranded DNAs can only anneal to one another if they are 100% identical in nucleotide sequence. Melting point (Tm) is the temperature at which the DNA is one-half double-stranded and one-half single-stranded. DNA is more likely to denature when exposed to a high pH.

Answer 1

Answer: "Decreasing the salt concentration of the solution lowers DNA's melting point (Tm)" is not a true statement

Explanation:

Increasing salt concentration would lower the DNA's melting point (Tm), not otherwise.

For instance:

- In 8M urea (8M means 8 Moles per dm3), Tm is decreased by nearly 20°C.

- 95% formamide at room temperature would completely denature the double stranded DNA.

Thus, higher concentration of salts like urea or formamide lowers Tm, not otherwise