histone

guanine modification proteins guanosine nuclear scaffold solenoid biochemistry replication structural phenotype activation acetylation compact histones polypeptide mutation peptide histone protein nucleosome methylation biotechnology deoxyribonucleic macromolecule h1 h3 h4 genetics h2a h2b health spiral human double biology model helix anatomical biological microscopic pathology anatomy scientific learning life dna cytosine molecular structure chromosome nucleotide genetic research chromatin vector chromatid cell science molecule sequence genome nucleic acid evolution medicine gene medical base physiological adenine healthy diagram people microbiology cartoon living