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Why is Dna antiparallel?

Is it got to do with the base pairing?
The nucleotides are arranged in a 3* and 5* formation so the DNA polymerase acts in opposite directions in order for the enzyme to be complimentary to the nucleotide shape.
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Chemmi
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Original post by WilmaWizard
The nucleotides are arranged in a 3* and 5* formation so the DNA polymerase acts in opposite directions in order for the enzyme to be complimentary to the nucleotide shape.

Thanks
No problem :smile:
Reply 4
Avatar for Lola1244
Lola1244
5
try drawing out the dna structure... i am not sure about the above answer but this is for definite-
the dna strands must run in opposite directions to allow complementary base pairing between bases facing inwards

lol does that even make sense?
Reply 5
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Lola1244
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Original post by WilmaWizard
No problem :smile:


hi, I'm not sure myself... but surely the enzyme acting in opposite directions is a RESULT of the dna strands being antiparallel, not the cause?

in my view they are antiparallel because the shape of the nucleotides is fixed, so the only arrangement in which the bases can be faced inwards to form complementary base pairing and H bonds etc is when one of the strands is running in an opposite direction
Original post by Chemmi
Is it got to do with the base pairing?


Original post by Lola1244
hi, I'm not sure myself... but surely the enzyme acting in opposite directions is a RESULT of the dna strands being antiparallel, not the cause?

in my view they are antiparallel because the shape of the nucleotides is fixed, so the only arrangement in which the bases can be faced inwards to form complementary base pairing and H bonds etc is when one of the strands is running in an opposite direction
They are antiparallel to allow the formation of weak hydrogen bonds between complimentary base pairs. So one strand runs from 3' to 5 and the other strand runs from 5' to 3'. So that a pyrimidine base such as Thymine forms 2 hydrogen bonds with a purine base - Adenine and another purine base such as Guanine forms 3 hydrogen bonds with a pyrimidine base - Cytosine. So that there is always 3 ring structures between phosphate backbone.

This occurs in DNA replication or Transcription (Thymine gets replaced by uracil here).:h:
(edited 7 years ago)
Reply 7
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Lola1244
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Original post by RedRosesBloom
They are antiparallel to allow the formation of weak hydrogen bonds between complimentary base pairs. So one strand runs from 3' to 5 and the other strand runs from 5' to 3'. So that a pyrimidine base such as Thymine forms 2 hydrogen bonds with a purine base - Adenine and another purine base such as Guanine forms 3 hydrogen bonds with a pyrimidine base - Cytosine. So that there is always 3 ring structures between phosphate backbone.

This occurs in DNA replication or Transcription (Thymine gets replaced by uracil here).:h:


thanks for clearing it up :-)

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