Structure of typical viruses, the smallest microbe on Earth. Virus is merely a packet of DNA or RNA information. This packet of information is sort of like an instruction manual on how to reproduce. Read more: http://easyscienceforkids.com/viruses-the-smallest-microbe-on-earth/
the 'race' betweeen human sperm to the eggs might just look like a bunch of wriggling tadpoles - but it makes a big difference which sperm wins. Even sperm cells from the same man have big genetic differences, a study has shown.
Genome of Denisovan cave girl sheds light on human ancestry. The only fossil evidence of Denisovans found to date is this tooth, another molar and the finger bone used in the recent study to sequence the genome.