Final answer:
The statement is true; histones are rich in basic amino acids like lysine and arginine, which give them a positive charge. This allows them to bind to the negatively charged DNA and play a vital role in DNA packaging within the cell nucleus.
Step-by-step explanation:
The statement is true: Histones contain a large number of basic amino acids and therefore are positively charged proteins. Histones, notably rich in lysine and arginine, are key components of chromatin structure in eukaryotic cells and are crucial for DNA packaging. Their positive charge allows for binding to the negatively charged phosphodiester backbone of DNA, facilitating the formation of nucleosomes where DNA wraps around histone octamers.
Within the nucleus, histones play an essential role in the organization of DNA into structural units called nucleosomes. Each histone octamer is associated with a particular section of DNA, leading to the 'beads-on-a-string' structure visible under an electron microscope after chromatin extraction with high salt concentration. This arrangement is fundamental to the compacting of DNA within the cell nucleus, enabling efficient management of the genetic material.
It is also interesting to note that the behavior of these basic amino acids in histones can be attributed to their ability to accept hydrogen ions (H+), making them basic in nature. Hence, charged groups like -NH3+ on lysine and arginine residues are integral to histone function.