In this chapter, we focused on how DNA is organized at the chromosomal level. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions: How did we learn that eukaryotic chromatin exists in the form of repeating nucleosomes, each consisting of about 200 base pairs and an octamer of histones?

Video transcript

Hello, everyone. Here we have a question asking us to choose the appropriate option from the following statements. A, a structure known as a nucleosome is formed when the positively charged DNA is encircled by the negatively charged Histone Omar. This is incorrect, DNA is negatively charged due to the phosphate groups and his stone omer is positively charged. So A is incorrect. B the two turns of DNA are sealed by H one, his stone molecules that are located inside the core of the molecule. H one could alter the amount of time that the DNA is accessible and unq by binding to the linker DNA segments that enter and exit the nucleus. What this would do is either prevent, completely prevent the linker DNA segments or spontaneous site exposure. But it is important to note that contrary to popular belief, H one is not a glue that binds two turns of DNA S within the nucleosome. So B is incorrect. See, a typical nucleosome contains 400 BP of DNA helix. This is incorrect DNA helix in a typical nus is approximately 200 BP. And lastly, we have d an additional set of proteins collectively referred to as nonhistone chromosomal proteins are required for the packaging of chromatin at a higher level. And this is correct. So our answer here is d thank you for watching. Bye.