"large molecule" is pretty misleading. DNA is single molecule and unrolled has length over 2 meters. Organic molecules are practically unlimited in their size.
Do you have a source on that? It didn't gut check with me and some quick googling turned up some contradictory, but not decisive, information otherwise [1]
Fourth post on the page gives a source:
This is from Molecular Biology of the Cell (4th Edition) 2004. Alberts et al. Textbook.
"Each human cell contains approximately 2 meters of DNA if stretched end-to-end"
Perhaps a human cell contains several DNA molecules?
technically correct but they are talking about touching the accessible surface of a compact molecule which is approximately spherical and thus "size" is determined by its raised profile on a surface.
