A person answered these questions from the article, he answered one of them wrong, I want you to find a wrong part and answer why is it wrong?
Questions:
What two main points did you understand from the abstract?
What methods were used to conduct the research? Why were they appropriate?
What key finding did you see in the results?
Provide a summary of the author’s conclusions.
Were the conclusions accurate for the results presented in the paper?
Answers based of article:
In this short abstract, the authors, Ada Olins and Donald Olins (who, notably, were married to one another), declare that they have observed “linear arrays of spherical chromatin particles” in isolated genetic material from rat thymus, rat liver, and chicken red blood cells.
The authors also suggest measurements for the diameter of these particles (about 70 angstroms) and the width of the strands between adjacent molecules (about 15 angstroms).
The existence and definition of these particles, along with suggestions regarding their physical properties, provide foundational evidence of nucleosomes as the basis for compacting DNA.
Regarding methodology, the authors used electron microscopy. This was an appropriate in that electron microscopes allow for the investigation of the structures of cells and large molecules – and, in this case, the reliable visualization and measurement of the chromatin units.
Further, the authors used genetic material from chicken blood, rat liver and calf thymus to isolate and study the nuclei at different phases of mitosis and using a range of methods to stain and visualize the structures in a manner that gave them confidence that the ultimate visual of “beads on a string” was a “native configuration” and not the result of the procedures that they are using.
Two main points revealed in this article are:
The initial observation of particles – defined in the article as “Spheroid Chromatin Units (v Bodies)”, and now understood to be nucleosomes – as “beads on a string”. This paper serves as the discovery of the nucleosome.
Initial conclusions regarding the structure of the nucleosome and the manner in which DNA is compacted. These inferences regarding the physical properties of the nucleosome provided an answer to outstanding questions regarding the manner in which DNA is packaged in chromosomes.
The primary conclusions of the paper are that: 1. The identification of the nucleosome, described as “beads on a string”; and 2.
Suggestions regarding the physical properties of the nucleosome and the manner by which DNA is packaged in chromosomes. The authors further conclude that these findings – which were made using electron microscopy – are consistent with models derived from earlier x-ray diffraction studies describing the packaging of DNA, the varying helical arrangements, and the measurements of the fibers and particles.
Taken together, these findings served as a breakthrough in understanding the way in which DNA is packaged and the structure of chromosomes.
The conclusions are accurate based on the results in the paper. In a way, the relationship between the results and the conclusions are one-in-the-same, in that the authors’ conclusions describe their observations of particles, now understood to be nucleosomes, using electron microscopy.
Further, based on these observations, the authors provide results relating to the physical properties of these particles, such as their arrangement and size, which serve as the basis for conclusions relating to the manner in which DNA is compacted in the chromosome.
The authors are confident in these conclusions due to precautions taken in their methodology to assure them that their observations are natural, and not the result of manipulation in the course of their experiments.
