Question

In order to fit inside the nucleus of a cell eukaryotic DNA needs to be compacted sinificantly (A) Discuss the role of histones in the compaction of eukaryotic DNA. Make sure you first define what histones are before describing how they aid in compaction. Also discuss how the enzyme Nase I was used to determine the structure of nucleosomes (B) What are radial loops, and how do they further aid in DNA Compaction! Be sure to state how the loops are arranged attached inside the nucleus.

Answer 1

A Histones are highly basic proteins found in eukaryotic cell nuclei that help in backage and order DNA into structural units Called mulleosome': "Theye ase five histone fractim in nudeosonne qisembly of which 4 ire. HQ A, H2B; H3 and H4 (2 molecules each) enter into the composition of nucleosome and form the core last While Hi Brolein serre as linker between the nucleosome beads. The octa mer is surrounded by DNA molecules having almost 200 bp of which approximately 140 bp enter into wiling of octemer and rest remain associated with H.linker? Treating nucleosome with Disane I lead to gradual digestion of Ha-linker DNA but nucleosome nemam partial resistance to nuclease activity. Analysis of size of DNA be show further treating octemer of nuclease lead to reduction of 2006 of DNA to 166 bb and finally to A6 bb and Hs is lost.. Nucleosome an suber coiling produce 30 nm of solenoid foram Jonim and finally solenoid fibre of 30nm organize into looks around a central scafford to make the tightly packed metaphane Chromosome (300mm) Arrangement - scaffold T (B)