Final answer:
A nucleosome core particle consists of DNA wound around an octamer of histones. It is the fundamental unit of chromatin and reveals a 'beads-on-a-string' appearance when observed under an electron microscope. These structures are crucial for DNA packing in the nucleus.
Step-by-step explanation:
A nucleosome core particle is comprised of DNA wrapped around a histone octamer. This structure appears as small beads on a string when viewed under an electron microscope.
Histone proteins are important in packing the DNA within the cell nucleus. They facilitate the compaction of the 2-metre-long DNA of a eukaryotic cell into a much smaller space, such as the 5-10 micrometre diameter nucleus. The nucleosome complex can control access to the DNA, making it crucial for processes like transcription.
The nucleosome is a fundamental unit of the chromatin structure and consists of DNA wound around an octamer of histones. The 'beads-on-a-string' form can be seen as the first-level packing of chromatin and is about 10 nm in diameter. Further compaction leads to the formation of a 30 nm fiber.