Question

QUESTION 44 west Because hydrogen bonds hold the two strands of a DNA molecule together, the strands can be separated ("melted") without breaking any covalent bonds. To melting temperature) is the point at which two strands separate, or become denatured. Order the DNA sequences listed below, according to relative meting temperatures from Tm to highest Tm). Assume that they all begin as stable double-stranded DNA molecules at room temperature i) CGGCGAGCCAGCCCCG 11) TTAATTGITTGTCTCT iii) GTACCCGTCCTGTGAC iv) CCTAATAGACGCTGOT OAI<tcllci Biliv Ochellesi Dicci

Answer 1

Answer:

Correct choice is A) II<IV<III<I

Melting point of a DNA strand is temperature at which 50% of DNA becomes single stranded by breaking of hydrogen bond.

It depends on length of strand and number of hydrogen bonds.

Guanine - Cytosine pair has got 3 hydrogen bonds

Adenine- Thymine bond has got only 2 hydrogen bonds.

In this question length of DNAs are similar with16 base pairs.

DNA labelled 1 has got 16 (all) 3 hydrogen bond pairs.

DNA 2 has got such 4 pairs

DNA labelled 3 has got 10 such pairs

4th DNA has got 8 such pairs

So from least to maximum temperature with standing order is

2<4<3<1