Morning, Gail! I think that H5a1 designation is probably a mitochondrial DNA (mtDNA) haplogroup. There's no analogous grouping for the X chromosome or any of the autosomes.
The thing that's so very different about yDNA and mtDNA is that neither of them undergo recombination. They're termed "uniparental DNA" because they're inherited along the patrilineal and matrilineal lines only, and their DNA changes only through mutation...in the case of mtDNA, mainly because it's such a tiny DNA molecule (it isn't part of our nuclear DNA, but in a very small organelle in our cells, sometimes thousands of them in a single cell), the mutation rates are glacially slow. Mitochondrial haplogroups typically represent timeframes in the thousands of years.
We each have mitochondria in all our cells expect red blood cells, but our mitochondria come only from our mothers. Though there have been extremely rare and isolated instances identified where the father's mtDNA was inherited by a child, that's so extraordinary that, for genealogy, it's safe to assume that all mtDNA in an individual came from the mother.
A good place to find out more about mtDNA is this first article in a series by Roberta Estes.
