Nobody will write your biology essay for you - and what mental affliction is preventing you from googling:
"prokaryotic and eukaryotic cell difference"
would it be inborn st00pidity or just lazziness? assuming first one - remove inverted commas - you know, these curly bits on the beginning and end of the sentence...
The total complement of genes in an organism or cell is
known as its genome, which may be stored on one or more chromosomes; the region
of the chromosome at which a particular gene is located is called its locus. A
chromosome consists of a single, very long DNA helix on which thousands of
genes are encoded. Prokaryotes-bacteria and archaea-typically store their
genomes on a single large, circular chromosome, sometimes supplemented by
additional small circles of DNA called plasmids, which usually encode only a
few genes and are easily transferable between individuals. For example, the
genes for antibiotic resistance are usually encoded on bacterial plasmids and
can be passed between individual cells, even those of different species, via
horizontal gene transfer. Although some simple eukaryotes also possess plasmids
with small numbers of genes, the majority of eukaryotic genes are stored on
multiple linear chromosomes, which are packed within the nucleus in complex
with storage proteins called histones. The manner in which DNA is stored on the
histone, as well as chemical modifications of the histone itself, are
regulatory mechanisms governing whether a particular region of DNA is
accessible for gene expression. The ends of eukaryotic chromosomes are capped
by long stretches of repetitive sequences called telomeres, which do not code
for any gene product but are present to prevent degradation of coding and
regulatory regions during DNA replication. The length of the telomeres tends to
decrease each time the genome is replicated in preparation for cell division;
the loss of telomeres has been proposed as an explanation for cellular
senescence, or the loss of the ability to divide, and by extension for the aging
process in organisms.
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