RICHARD KAIL / SCIENCE PHOTO LIBRARY RICHARD KAIL / SCIENCE PHOTO LIBRARY
DNA histone. Computer illustration showing a DNA (deoxyribonucleic acid) molecule wrapped around a histone (centre). DNA is composed of two strands twisted into a double helix. Each strand consists of a sugar-phosphate backbone attached to nucleotide bases. Segments of DNA are packaged within the nuclei of cells by being wrapped around eight histone protein cores into structural units called nucleosomes.
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