Difference between dna packaging in eukaryotes and prokaryotes
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Answer:
Explanation:
At the chemical level, the DNA of prokaryotic cells, which have no nuclear membranes, and that of eukaryotic cells, which have separate, membrane-enclosed nuclei, is identical. DNA is a long, double-stranded molecule containing a backbone of repeating, alternating sugar and phosphate units. One of four different nucleotide bases, cyclic molecules containing nitrogen, hangs off each sugar unit. Differences between the DNA of the two organism types include its packaging, quantity, replication and information content.
Packaging
Prokaryotes and eukaryotes package their DNA molecules with protein in structures called chromosomes. A prokaryotic chromosome is circular and resides in a cell region called the nucleoid. The types of proteins found in prokaryotic chromosomes, known as the nucleoid-associated proteins, differ from the histone proteins that appear in eukaryotic chromosomes and cause the prokaryotic chromosomes to form looped structures. Unique eukaryotic chromosome packaging features include tight coiling, dense packing, enclosure within a nuclear membrane and linear rather than circular structures.
Quantity
Prokaryotes typically have one main chromosome, through it might have a few copies of it. These cells can also have smaller DNA structures called plasmids that contain additional information. The number of nucleotide base pairs in the prokaryotic chromosome ranges from 160,000 to 12.2 million, depending on the species. Eukaryotes frequently have multiple types of chromosomes with many more base pairs. For example, humans have 23 pairs of chromosomes, the maternal and paternal sets, containing about 2.9 billion base pairs in total.
Replication
Cells must replicate their DNA before dividing. Prokaryotic replication is relatively simple. The copying of the DNA strands begins at a single point of origin on the prokaryotic chromosome, and only one replication fork and bubble is formed during replication. Prokaryotic DNA replication is speedy, about 2,000 base pairs per second. Eukaryotic DNA replication relies on multiple replication origins, forks and bubbles to compensate for a slow pace, about 100 base pairs per second. In prokaryotes, only two proteins are required to initiate replication, whereas eukaryotes use complexes composed of multiple protein subunits.
Information Content
Prokaryotic DNA gene sequences are organized as operons, each of which can code for multiple proteins. The size, sophistication and number of encoded proteins is relatively small, but a high percentage of the prokaryotic DNA strand encodes proteins. Eukaryotic DNA is organized in genes that each code for a single protein, although in some cases multiple genes might be transcribed at the same time. About 5 percent of eukaryotic DNA codes for proteins or RNA, but much of the remaining DNA helps identify gene and control gene expression. Prokaryotic cells usually have a single version of each gene, whereas eukaryotes normally have two versions, one from each parent.
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Answer:
DNA Packaging in Cells. Prokaryotic are much simpler than Eukaryotas in many of their features. A Eukaryota contains a well-defined nucleus, whereas in prokaryotic, the chromosome lies in the cytoplasm in an area called the nucleotide.
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