Why not count down the days of the advent chromosome by chromosome? It’s a great idea and the Royal Institution’s implementation of it is excellent, try it.
When you visit their advent website, you’ll see a karotype,* with a microscope lens in middle.
We have 23 pairs** of chromosomes: one pair of sex chromosomes (XX in women, XY in male) and 22 pairs of autosomes (non-sex chromosomes) numbered 1 to 22.
We also all have a small organelle that is involved in ‘energy’ processing in our cells, the mitochondria. It has it’s own little chromosome, known for being passed down only from our mothers,*** that is counted as the 24th chromosome for this advent calendar.
Move the lens around to locate each day’s calendar (you can change the focus, too). Days that haven’t yet come to pass aren’t labelled.
Each day has a short film exploring part of that chromosome and interesting genetics associated with it. If you’re thinking amateur science videos, don’t. Think more BBC documentary.