Why is Dna antiparallel? Watch

Chemmi
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Is it got to do with the base pairing?
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WilmaWizard
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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.
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WilmaWizard
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No problem
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Lola1244
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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?
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Lola1244
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(Original post by WilmaWizard)
No problem
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
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RedRosesBloom
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(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).
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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).
thanks for clearing it up :-)
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