Final answer:
Histone H1 is the protein that 'seals' off DNA, by binding to the linker DNA between nucleosomes and facilitating the higher structure of chromatin, making it the correct answer.
Step-by-step explanation:
The histone protein that seals off the DNA, helping compact it into a structure known as chromatin, is H1. Histone H1 is often referred to as the linker histone because it binds to the DNA between nucleosomes and locks it in place around the nucleosome core, facilitating the higher-order structure of DNA. This is essential for the proper packaging of DNA into chromatin and for regulating access to the DNA for processes such as transcription and replication. Histones H2A, H2B, H3, and H4 form the core around which DNA is wound to create nucleosomes, but H1 is the one that 'seals' the DNA, making choice (A) I only, the correct answer.
Histone proteins are crucial for DNA packaging. They are basic proteins that bind to the negatively charged phosphodiester backbone of DNA. One specific histone protein, H1, seals off the DNA by binding to the linker DNA between nucleosomes, helping to compact the DNA into a more organized structure Histone proteins H2A, H2B, H3, and H4 form the nucleosome core.