Molecular clock - overview image showing how mutations in conserved regions accumulate slowly over time at a regular rate.
Receptor (biochemistry) - an animation / .gif showing a more accurate representation of how membrane receptors receive signals and convey them into the cytoplasm to their secondary messenger
Mutations - A quick guide to/table of mutations - including Frameshifts, SNPs, insertions, deletions, substitutions, etc.
Mutations - a guide to mutations including silent (no change to AA), quiet (change of AA to one with similar properties, beneficial mutations (novel AA), harmful mutation (novel AA)
Protein structure - a simple guide to the four levels of protein structure (there a nice interactive diagram, but it might be hard to understand for beginners)
Sex verification in sports - flow chart/process diagram showing steps of professional gender verification.