Re: What's the length of a strand of human DNA compared to other animals?

well, this is a hard question to answer but i  will try.  According to Watson et al in "Molecular Biology of the Gene", 4 Ed each chromosome in a mammalian cell is believed to be made up of a single very long DNA molecule which is about 5cm in length.  This is effectively compacted into each chromosome.  A study of the DNA lengths in each chromosome in several organisms using the Entrez database on the internet shows that the base pair lengths in each chromosome of several evolutionary distinct organisms can be quite different.  Some of the data is shown in table 1:

Table 1                                                                               Table 2


Organism         Chromosome            Chromosome length in Bp                        Organism                  Length of mitochondrial DNA
Homo Sapiens       20                      90 000 K                                   Homo sapiens              16 K
Homo Sapiens       19                      100 000 K                                  great Indian Rhino        16829
Homo Sapiens       17                      125 000 K                                  donkey                    16670
Homo Sapiens       6                       225 000 K                                  atlantic cod              16696
Dros. Melanogaster 4                       1750 K                                     locust(L.migratoria)      15722
Dros. Melanogaster 3                        50 000 K                                  
Dros. Melanogaster 2                        51 000 K
Mouse (Mus musculus)11                      45000 K


If we consider the mitochondrial DNA we see much greater homogeneity in DNA length (Table 2).  This is most likely explained by the theory that mitochondria were once separate organisms that were incorporated into the cellular structure of eukaryotic cells.  The slight differences in mitochondrial DNA length are due to heteroplasmy, that is differences in length of the control regions of the mitochondrial DNA.


Overall it is possible to say that there only a very approximate increase in the  degree of complexity of organisms (number of different proteins produced) with increasing size of genomes.  Whilst this latter fact is indirectly related to your question, it is nevertheless an interesting fact.

I hope this answer was to the point and not too brief.

                                                       Robert DEYES BSc MSc