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InterviewSolution
| 1. |
0.7.8.ifferentiatebetween 'prokaryotic' andkaryotic' cells. |
| Answer» <p>The difference between the structure of prokaryotes and eukaryotes is so great that it is considered to be the most important distinction among groups of organisms.</p><p>The most fundamental difference is that eukaryotes do have "true" nuclei containing their DNA, whereas the genetic material in prokaryotes is not membrane-bound.</p><p>Structure and contents of a typicalGram-positive bacteriumcell (a prokaryotic cell)</p><p>In eukaryotes, the mitochondria and chloroplasts perform various metabolic processes and are believed to have been derived from endosymbioticbacteria. In prokaryotes similar processes occur across the cell membrane; endosymbionts are extremely rare.</p><p>The cell walls of prokaryotes are generally formed of a different molecule (peptidoglycan) to those of eukaryotes (many eukaryotes do not have a cell wall at all).</p><p>Prokaryotes are usually much smaller than eukaryotic cells.</p><p>Prokaryotes also differ from eukaryotes in that they contain only a single loop of stable chromosomal DNA stored in an area named the nucleoid, while eukaryoteDNAis found on tightly bound and organised chromosomes. Although some eukaryotes have satellite DNA structures called plasmids, these are generally regarded as a prokaryote feature and many important genes in prokaryotes are stored on plasmids.</p><p>Prokaryotes have a larger surfaceareato volume ratio giving them a higher metabolic rate, a higher growth rate and consequently a shorter generation time compared to Eukaryotes.</p><p>Genes</p><p>Prokaryotes also differ from eukaryotes in the structure, packing, density, and arrangement of their genes on the chromosome. Prokaryotes have incredibly compact genomes compared to eukaryotes, mostly because prokaryote genes lack introns and large non-coding regions between each gene.</p><p>Whereas nearly 95% of the human genome does not code for proteins orRNAor includes a gene promoter, nearly all of the prokaryote genome codes or controls something.</p><p>Prokaryote genes are also expressed in groups, known as operons, instead of individually, as in eukaryotes.</p><p>In a prokaryote cell, all genes in an operon(three in the case of the famous lac operon) are transcribed on the same piece of RNA and then made into separate proteins, whereas if these genes were native to eukaryotes, they each would have their own promoter and be transcribed on their own strand of mRNA. This lesser degree of control overgene expressioncontributes to the simplicity of the prokaryotes as compared to the eukaryotes.</p> <p>in prokaryotes cell there is no distinact nucleus & cell organellsin eukaryotes there is distinct nucleus & other cell organelles are present</p> | |