How is all of that DNA packaged so tightly into chromosomes and squeezed into a tiny nucleus? Long, slender DNA molecules wind around proteins and fold in complex ways to form chromosomes.

(A) Electron micrograph of a human cell section showing ... ubiquinone in green labeled with a Q; cytochrome c reductase in light blue; cytochrome c in dark blue labeled with cytC; cytochrome ...

The picture shows a close-up of one carbon atom. A hydrogen atom has one proton as the nucleus and one electron in the region outside the nucleus. The electron and proton are attracted to each other.