Search results
Results from the WOW.Com Content Network
Most prokaryotes, relying on circular chromosomes, accordingly do not possess telomeres. [12] A small fraction of bacterial chromosomes (such as those in Streptomyces , Agrobacterium , and Borrelia ), however, are linear and possess telomeres, which are very different from those of the eukaryotic chromosomes in structure and function.
By contrast, most eukaryotes have linear DNA requiring elaborate mechanisms to maintain the stability of the telomeres and replicate the DNA. However, a circular chromosome has the disadvantage that after replication, the two progeny circular chromosomes can remain interlinked or tangled, and they must be extricated so that each cell inherits ...
The main features of replication origins are sequences where specific initiation proteins are bound. A typical replication origin covers about 100-200 base pairs of DNA. Prokaryotes have one origin of replication per chromosome or plasmid but there are usually multiple origins in eukaryotic chromosomes.
The telomere-shelterin complexes that cap all eukaryotic chromosomes ensure that healthy cells can progress through the cell cycle by preventing the cellular DNA damage response from identifying chromosome ends as double-stranded breaks (DSBs). [4] [5] Without a protective cap, chromosome ends would appear identical to intrachromosomal DSBs ...
The genomes of most eukaryotic mitochondria and plastids are in a single circular chromosome, in line with their bacterial ancestor. However, a good number of eukaryotic species do harbor linear Mitochondrial DNA (mtDNA), some even broken into multiple molecules, across a wide variety of taxa: animals (mammals, medusozoans, sponges), fungi (especially yeast), plants, and Alveolatas.
Prokaryotic DNA Replication is the process by which a prokaryote duplicates its DNA into another copy that is passed on to daughter cells. [1] Although it is often studied in the model organism E. coli, other bacteria show many similarities. [2] Replication is bi-directional and originates at a single origin of replication (OriC). [3]
Many cancer cells are considered 'immortal' because telomerase activity allows them to live much longer than any other somatic cell, which, combined with uncontrollable cell proliferation [46] is why they can form tumors. A good example of immortal cancer cells is HeLa cells, which have been used in laboratories as a model cell line since 1951.
Prokaryotic chromosomes have less sequence-based structure than eukaryotes. Bacteria typically have a one-point (the origin of replication) from which replication starts, whereas some archaea contain multiple replication origins. [26] The genes in prokaryotes are often organized in operons and do not usually contain introns, unlike eukaryotes.