Extrachromosomal Circular DNA are composed of chromatin and replicate in the nucleus of the cell during cell division. Unlike typical chromosomes, they are composed of circular fragments of DNA, up to only a few million base pairs in size and contain no centromere or telomere. Extrachromosomal Circular DNA Extrachromosomal circular DNA (eccDNA) is circular DNA found in the nuclei of plant and animal cells, including human cells, in addition to chromosomal DNA. eccDNA can be from 200 up to 5 million base pairs in length. eccDNA has been found in the nuclei of human cancer cells and shown to carry many copies of
Cell cycle checkpoint Cell cycle checkpoint All living organisms are the products of repeated rounds of cell growth and division. During this process, known as the cell cycle, a cell duplicates its contents and then divides in two. The purpose of the cell cycle is to accurately duplicate each organism's DNA and then divide the cell and its contents evenly between the two resulting cells. In eukaryotes, the cell cycle consists of four main stages: G, during which a cell is metabolically active and continuously grows; S phase, during which DNA replication takes place; G, during which cell growth continues and the cell