In class we discussed how the G-C pairs easily explain the need for DNA strands
ID: 218019 • Letter: I
Question
In class we discussed how the G-C pairs easily explain the need for DNA strands to align in anti-parallel orientation for the base pairing to occur. Flipping either base prevented the proper H-bonds to form between the nitrogenous bases. But let's now take a look at the A-T pair in the image. It would appear that given thymidine's symmetry, you could flip the bases and two H-bonds would still form between either anti-parallel (5'-3' ll 3'-5) or parallel(5'-3' ll 5'-3') helices N-H..O CH If true, then DNA made of only As and Ts would not have to "worry" about the relative orientation ofthe strands, might advantageous ? ? C--C NH-N C-N which If any of this were true, why do you think that evolution may have gone down the road of including C-G pairs and impose a condition of anti-parallelism between strands? Why could have a DNA made of only As and Ts have been less evolutionarily advantageous?Explanation / Answer
DNA is double-stranded and the strands run antiparallel because they run in opposite directions. DNA molecule has two strands of nucleotides. Individual strand has a sugar-phosphate backbone, however, the orientation of the sugar molecule is different in the two strands. each strand of DNA double helix can build in 5' to 3' direction, but they grow in opposing directions because of the opposite positioning of the sugar molecule in them.
The antiparallel orientation allows the base pairs of DNA to compliment each another. Antiparallel DNA is more structurally stable than parallel DNA. The antiparallel orientation of DNA has significant involvements for DNA replication. since at the replication fork, one strand enables uniform replication, which is known as leading strand while the another becomes lagging strand.
parallel DNA structures are:
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