Question

A strange new species of plant has been discovered. When studying the chromatin from the cells of this plant using the kinds of experiments described above in (b) a 120-bp fragment of DNA is seen. Analysis of the histone core reveals histones in the following proportions: H2A 33.3% H2B 33.3% H3 0% [no histone H3 found] H4 33.3% On the basis of these observations, what conclusions can you make about the probable structure of the nucleosome in the chromatin of this plant? Be specific in describing the nature of the nucleosome: which histones form the core (1pt), how many of each are in there (1pt) and how much core-DNA is around it (1pt).

Answer 1

The nucleosome core is composed of two each of histones H2A and H2B and H4

Step-by-step explanation:

The nucleosome is the basic structural unit of all eukaryotic genomes. A nucleosome is composed of approximately 146 base pairs of DNA sequence wrapped around a core of histone proteins, which generally consists of two subunits of the histones H2A, H2b, H3 and H4, respectively (i.e., an octamer of histone proteins). Within the cell nucleus, the large DNA molecule is coiled into nucleosomes, this structure is further compacted into chromatin fibers and subsequently into higher-order organization structures to finally form a chromosome.