DNA, Chromosome, Chromatin. What's the Difference?

In this video, we'll explore the difference between a DNA molecule, chromatin, and a chromosome. IMPORTANT POINTS TO LEARN A DNA molecule is a double helix, huge and long, literally up to a meter per cell. In chemistry, DNA is a polymer, and its monomer is a nucleotide. All the genes the cell needs are located here. In other words, the recipes for protein synthesis are found in DNA. But the question arises: how can this long molecule be squeezed into a small nucleus? For this purpose, nature has devised a way to wrap DNA around special proteins called histones. Imagine a thread wound around a spool. The same principle applies here. And this DNA, bound to histones, is called chromatin. For the purposes of the Unified State Exam, we're only interested in histones; we'll leave the other proteins out of the equation—we don't need them right now. Important: in a normal cell, when it's living its normal life and not about to divide, we see chromatin in the nucleus. Chromosomes don't exist as separate structures at this point—they simply don't exist. Chromosomes only appear during cell division. During the prophase of mitosis or meiosis, chromatin becomes extremely compact, coiling even tighter around itself, and we see the familiar "X-shaped" structures—these are chromosomes. In other words, a chromosome is the highest degree of compaction of the DNA molecule.