Talk:Heavy strand

What are the functional differences in the strands?

It is obvious they are of different weights, but what is the significance of this?--74.124.187.76 (talk) 06:02, 2 March 2009 (UTC)

I think it's just to do with the ability to distinguish the strands on fractionation by weight - ie no biological significance, but a practical one. A and G (purines) are heavier than C and T (pyrimidines) due to an extra ring. Because a purine always pairs with a pyrimidine, any excess of purines in one strand will be complemented by an excess of pyrimidines in the other and vice versa. Statistically, there is more likely to be such an imbalance than an exact 50/50 ratio. Protein-coding biases may reinforce this effect. Allangmiller (talk) 12:16, 31 May 2010 (UTC)

Re: Edit 31/05/10

@Adrian Hunter: Although the bare term 'codon usage bias' seems a fair way of expressing what I was after, the Wiki linked to is restrictive to a tendency to favour one of a number of potential synonyms. I was thinking as much of the general causes of uneven codon representation - there is a bias within synonyms, for sure, but there is also a bias towards those codons representing the commoner acids. I can't say whether the Codon Usage Bias article reflects common usage, or whether it is missing that more general bias. A minor point; I'm not too fussed! 163.156.240.17 (talk) 11:36, 1 June 2010 (UTC)

Ah yes, I see your point. I've always understood "codon usage bias" to refer specifically to the difference in frequency between synonymous codons. But as you say, the CG content of a coding strand may also be influenced by which amino acids are more common, so your version was actually more precise. What do you think of this version? Adrian J. Hunter^{(talk•contribs)} 15:47, 1 June 2010 (UTC)

Yep, that's fine, thanks. Allangmiller (talk) 16:44, 6 June 2010 (UTC)

Different definitions of Light vs. Heavy

I ran across this paper and found a conflicting definition of Light vs Heavy strand in mitochondrial genomes. The original definition was based on an alkaline cesium chloride solution, where strands with higher G+T content would have more negative ions from donating protons, and thus associate with more cesium ions than chloride ions, and cesium is heavier than chloride. Thus the "Heavy strand" would be the one with higher G+T content rather than the one with higher G+A (purine) content. Can anyone with better expertise resolve this conflict?

I'm also new to editing so any reminders or tips are welcome. Cmgmcg (talk) 17:25, 1 June 2026 (UTC)