Three Experiments Regarding DNA

Experiment # 1 James Watson, Maurice Wilkins and Francis Crick together worked to find the structure of DNA or DNA. Wilkins and Rosalind Franklin used X-ray diffraction to examine the DNA from the image, finally announced discovery of the DNA structure in April 1953 and discovered how the genetic information was encoded on DNA. Watson discovered from the Franklin lecture that DNA exists in two forms depending on the humidity of the air.

Replication occurs in three main stages: cleavage of the double helix and separation of the DNA strand, initiation of the template strand, and assembly of new DNA segments. During separation, the two chains of the DNA double helix expand at a specific location called the start point. Thereafter, several enzymes and proteins cooperate to create or initiate strands for replication. Finally, a special enzyme called DNA polymerase organizes a collection of new DNA strands. Although the following description of this three step process is generally applicable to all cells, certain changes in the process may be dependent on organism and cell type.

Within a cell, DNA replication begins at a specific location within the genome or at the origin of replication. Initiation of DNA and synthesis of new strands are regulated by enzymes called helicases, resulting in bidirectional growth of replication forks from the origin. Many proteins are involved in replication forks and contribute to the initiation and continuation of DNA synthesis. Most notably, DNA polymerase synthesizes new strands by adding nucleotides complementary to each (template) strand. DNA replication occurs in the S phase of that interval

DNA polymerase is an enzyme involved in DNA replication; it includes seven different enzyme families. Of the seven DNA polymerase families, prokaryotes and eukaryotes share three DNA polymerase families: DNA polymerases A, B and Y. The DNA polymerase C family is only included by prokaryotes. Pol III is a replication DNA polymerase belonging to the DNA polymerase family C. DNA contained in eukaryotes is called eukaryotic DNA. Eukaryotic DNA is present in the nucleus of eukaryotic cells. Several eukaryotic DNAs also exist in organelles such as chloroplast and mitochondria. Eukaryotic DNA is surrounded by nuclear envelope. Eukaryotic DNA is organized into several linear chromosomes. Histones are proteins involved in the packaging of eukaryotic chromosomes in the nucleus. Tight winding and dense packing are features of eukaryotic chromosome packaging