Master Chromosome Components with Picmonic for Medicine

The components that make up a chromosome can be broken down through many levels into the basic unit, a DNA strand. The DNA strand is made up of nucleotides and the sugar-phosphate backbone, and has the appearance of a double-stranded helix. The DNA is wrapped around organizational proteins called histones, similar to how thread is wrapped around a spool. When eight or more histones are compacted together, they form a nucleosome. The nucleosome is the basic structural unit of chromatin, which is still not fully condensed. Chromatin will have many nucleosomes separated by unspooled DNA strands. When the chromatin becomes condensed during replication and division, it is called chromatid. A chromosome is simply one chromatid or two sister chromatids. The terms chromatid and chromosome are typically used only in the context of replication, as the genetic information exists as uncondensed chromatin most of the time. Finally, the telomere is a cap of repetitive nucleotide sequences placed on the ends of chromosomes that help protect it from degradation and fusion with another chromosome.