Is it the number and sequence of bases in a DNA that distinguishes

[curiosium]

species between species? Or does it only distinguish between a human and a chimpanzee?

[Dr.Knight M.D]

distinguish between the species

[secretsauce]

The exact number of bases is not that important ... but the number of genes (each of which contains thousands of base pairs) is important in determining whether the DNA from two individuals can produce offspring.

The exact sequence of bases determines the content of the genes. So two individuals (except for two identical twins) will have many differences in the exact sequences of base-pairs. Two species will have many more differences in the sequence of base-pairs. The more distant the two species, the more differences in the exact sequences of base-pairs in shared genes, and if far enough apart, there may be entire genes that are different between them.

And this is true between a human and a chimpanzee, or any two species.

[cheetah]

its the number of chromosomes which usually helps distinguishing species. sequence of bases can be different for different individuals even within the same species!