Question

Which of the following DNA molecules is the most stable?

1) 5'-CTGCATAC-3'
3'-GACGTATG-5'
2) 5'-GAAATTTC-3'
3'-CTTTAAAG-5'
3) 5'-AGTCGAAT-3'
3'-TCAGCTTA-5'
4) 5'-GCGTGCAC-3'
3'-CGCACGTG-5'
5) 5'-GGATCCTG-3'
3'-CCTAGGAC-5'

Answer 1

The most stable DNA molecule among the given options is option 4 (5'-GCGTGCAC-3' and 3'-CGCACGTG-5').

Step-by-step explanation:

The stability of DNA molecules is determined by the strength of the hydrogen bonds formed between complementary base pairs. In DNA, adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds.

Looking at the given options, we can identify the complementary base pairs for each DNA molecule:

1. Option 1: Complementary base pair sequence is 3'-TCAGTATA-5'
2. Option 2: Complementary base pair sequence is 3'-CTTAAAGA-5'
3. Option 3: Complementary base pair sequence is 3'-TCGACTTA-5'
4. Option 4: Complementary base pair sequence is 3'-CGCACGTG-5'
5. Option 5: Complementary base pair sequence is 3'-CCTAGGAC-5'

Based on the number of hydrogen bonds formed, option 4 (5'-GCGTGCAC-3' and 3'-CGCACGTG-5') is the most stable as it has the highest number of hydrogen bonds (six). Therefore, option 4 is the most stable DNA molecule among the given options.