Biochemistry - DNA Structure and Replication - Discussion

Discussion Forum : DNA Structure and Replication - Section 1 (Q.No. 19)
19.
In the study of one experiment it was found that the value of Tm for DNA is = 40° C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%?
Remains same
Increases
Decreases
Can not be compared
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
3 comments Page 1 of 1.

Siva ram said:   8 years ago
G-C base pair has three hydrogen bonds while A-T base pair has two hydrogen bonds.

Hence, DNA sequences with higher G-C content are relatively tightly held together and have a higher melting point.

Durga said:   1 decade ago
Primers with a 40-60% GC content ensure stable binding of primer/template. G-C bonds contribute more to the stability (increased melting temperatures) of primer/template binding than do A-T bonds.

Angel said:   1 decade ago
The %GC cannot really increase for a given species, and "the cell has 2'% at the above Tm" is not a good wording.

It would be better to present as 2 species, one with 20% GC and the other with 60% GC, and compare the Tm of DNA from each species.

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