An examples of a comparison intended to portray scale:
"Imagine DNA as a ladder, with each base representing a rung, and each rung being 25cm form the next. The ladder would stretch 75 million kilometres, roughly from earth to Mars (depending on the relative positions of their orbits on the day the ladder was put in place)."
Nessa Carey (2015) Junk DNA. A journey through the dark matter of the genome. London: Icon Books Ltd.
(A strand of DNA can in principle, in molecular terms, be very short or extremely long, but the context from which the quote is taken suggests 'DNA' here refers to all the DNA in a single human cell.)
Read about quotidian comparisons
