:because hydrogen bonds hold the two strands of a dna molecule together, the strands can be separated without breaking any covalent bonds. every unique dna molecule "melts" at a different temperature. in this context, tm (melting temperature) is the point at which two strands separate, or become denatured. order the dna sequences listed below according to relative melting temperatures (from lowest tm to highest tm). assume that they all begin as stable double-stranded dna molecules. explain your answer. a. ctaactgg b. tattgtct c. gactcctg d. ggcgcacc

B. TATTGTCT A. CTAACTGG D. GGCGCACC C. GACTCCTG

Explanation:

Give 2°C to each A-T pair and 4°C to each G-C pair. The Tm will be the sum of these numbers for each pair in the DNA double strand. This has taken care the fact that the G-C bond is stronger than the A-T bond. Therefore: Tm = 2 °C(A + T) + 4 °C(G + C)

A. We have 2A, 2T, 2G and 2C

Tm= 2°C(2+2)+4°C(2+2)

Tm= 2°C(4)+4°C(4)

Tm= 8°C+16°C

Tm= 24°C

B. Use the same formula to get Tm for DNA sequence in B. The Tm for DNA sequence in B is 20°C

C. The Tm is 30°C

D. The Tm is 26°C

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex