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Length of Human DNA.

Ivan Moller ivan.m at vip.cybercity.dk
Sat Nov 29 10:00:30 EST 1997

> How many nucleotides are in human DNA?
> And, is the number of nucleotides in human DNA constant across humans
> Is that number close? 6 billion? Or are there much more or much less?
> I read in a book that there were 200,000 genes in human DNA, and it said
> 1000 nucleotides per gene, which has to be an approximation, right? Since
> nucleotides gives you an amino acid, wouldn't the number of nucleotides
in a 
> gene have to be evenly divisible by 3?
> But by that calculation, 200 million base pairs approximately in a human
> DNA?

The correct size of the human genome is 2.8 bilion base pairs (two

Your calculation assumes that the DNA only consists of genes, like pearls
a string, which is not correct. 
Yes, the number of base pairs that encodes the protein is divisible by 3.

> How do we know that introns are non functional? Introns exist within a
> gene, right?

All we know is that they don't encode the final protein, as they are
spliced out of the messenger RNA, than encodes the protein.

> Not junk outside of start and stop codons, right?

No, it's inside the start and stop codon.

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