Search results
Results from the WOW.Com Content Network
The term plasmid was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." [11] [12] The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time ...
Eukaryotic cells are some 10,000 times larger than prokaryotic cells by volume, have their DNA organised in a nucleus, and contain membrane-bound organelles. The division between prokaryotes and eukaryotes has been considered the most important distinction or difference among organisms.
Paracoccus denitrificans has two circular chromosomes and one large plasmid, [23] carrying genes not essential for survival but key to its biochemical behavior. [24] The second chromosome has also been called a chromid , in that they have similar codon usage to the chromosome, are essential to life like the main chromosome, but has plasmid-type ...
Chromids, [1] formerly (and less specifically) secondary chromosomes, [a] are a class of bacterial replicons (replicating DNA molecules). These replicons are called "chromids" because they have characteristic features of both chromosomes and plasmids. Early on, it was thought that all core genes could be found on the main chromosome of the ...
Homologous chromosomes contain highly similar but not identical information, and by exchanging similar but not identical regions, genetic recombination increases genetic diversity among future generations. [11] During sexual reproduction, two haploid gametes combine into one diploid cell known as a zygote in a process called fertilization. The ...
The nucleoid (meaning nucleus-like) is an irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material. [1] [2] [3] The chromosome of a typical prokaryote is circular, and its length is very large compared to the cell dimensions, so it needs to be compacted in order to fit.
Replication occurs much faster in prokaryotic cells than in eukaryotic cells; bacteria sometimes only take 40 minutes, while animal cells can take up to 400 hours. Eukaryotes also have a distinct operation for replicating the telomeres at the end of their last chromosomes. Prokaryotes have circular chromosomes, causing no ends to synthesize.
These methods have resulted in novel perspectives on genetic relationships that previously have only been estimated. [5] A significant achievement in the second decade of bacterial genome sequencing was the production of metagenomic data, which covers all DNA present in a sample. Previously, there were only two metagenomic projects published. [5]