Replication in eukaryotes

The multiple sites that serve as origins for DNA replication in eukaryotes are poorly defined except in a few animal viruses and in yeast. However, it is clear that initiation is regulated both spatially and temporaUy, since clusters of adjacent sites initiate rephcation synchronously. There are suggestions that functional domains of chromatin replicate as intact units, implying that the origins of rephcation are specificaUy located with respect to transcription units. 

Expression of Potential Vaccine Antigens. In general, in the future, eukaryotic cell culture is likely to be the method of choice for the production of subunit vaccine antigens where the organism to be vaccinated against replicates in eukaryotic cells. E. coli are unable to posttranslationally modify some vaccine candidates for example, bacterial systems cannot add carbohydrate which is important in the antigenicity and structure of many protective antigens. 

Covalent links of histones HI, H2A, H2B, and H3 with poly(ADP-ribose) have been reported (for references, see Hayaishi and Ueda, 1977). Furthermore, a histone HI dimer linked by poly(ADP-ribose) has been reported. The increase in ADP-ribosylation is concomitant with cellular replication and ADP-ribosylation has been proposed as a trigger for in vivo replication in eukaryotic cells. 

The mechanism of replication in eukaryotes is believed to be very similar to this. However, the details have not yet been completely worked out. The steps and proteins involved in DNA replication in prokaryotes are compared with those used in eukaryotes in Table 1-2-2. 

The process of eukaryotic DNA replication closely follows that of prokaryotic DNA synthesis. Some differences, such as the multiple origins of replication in eukaryotic cells versus single origins of replication in prokaryotes, have already been discussed. Eukaryotic single-stranded DNA-binding proteins and ATP-dependent DNA helicases have been identified, whose functions are analogous to those of the prokaryotic enzymes previously discussed. In contrast, RNA primers are removed by RNase H. 

DePamphilis, M. L., ed. (1996) DNA Replication in Eukaryotic Cells, Cold Spring Harbor Lab. Press, Cold Spring Harbor, New York... 

Replication of the Escherichia coli Chromosome Initiation and Termination of Escherichia coli Chromosomal Replication DNA Replication in Eukaryotic Cells Eukaryotic Chromosomal DNA SV40 Is Similar to Its Host in Its Mode of Replication... 

Related topics DNA replication in bacteria (F3) Transcription in DNA replication in eukaryotes (F4) prokaryotes (G2) RNA structure (Gl) Transcription in eukaryotes an overview (G5)... 

The control of DNA replication in eukaryotes is more complex than in bacteria. Once a cell enters S phase, the multitude of individual replicons throughout the genome probably replicate in a defined order. It is known that, in some situations, the duration of S phase can vary greatly. 

Question What are the structural features of origins of replication in eukaryotes and how is initiation... 

Sharova, N.P., and E.B. Abramova. Initiation of DNA replication in eukaryotes is an intriguing cascade of protein interactions. Biochemistry 2002 67 1217-1223. 

Replication in eukaryotes is mechanistically similar to replication in prokaryotes but is more challenging for a number of reasons. One of them is sheer size E. coli must replicate 4.8 million base pairs, whereas a human diploid cell must replicate 6 billion base pairs. Second, the genetic information for . coli is contained on 1 chromosome, whereas, in human beings, 23 pairs of chromosomes must be replicated. Finally, whereas the E. coli chromosome is circular, human chromosomes are linear. Unless countermeasures are taken (Section 27.4.7), linear chromosomes are subject to shortening with each round of replication. 

DNA synthesis occurs during the process of replication. Replication is the pncMcess by which DNA synthesis causes all the DNA in the nucleus to make a duplicate of itself. In eukaryotic ceils, the process of replication causes the cell to change from a diploid cell to one that is temporarily tetraploid. Replication in eukaryotic cells is usually immediately followed by cell division, which results in two cells that are once again diploid. 

DNA replication is initiated at a single site within the E. coli genome. A set of specific proteins recognize this origin of replication and assemble the enzymes needed for DNA synthesis, including a he-licase that promotes strand separation. The initiation of replication in eukaryotes is more complex. DNA synthesis is initiated at thousands... 

Initiation of DNA replication in eukaryotes appears to be more complex than what has been found in bacteria. 

DNA replication in eukaryotes is more complex. The human genome consists of approximately three billion nucleotide pairs. Just one chromosome may be nearly one hundred times longer than a bacterial chromosome. To accomplish this huge job, DNA replication begins at many replication origins and proceeds bidirectionally along each chromosome. 

Higher Order Chromatin Structure in the Nucleus (Figure 28.12, Figure 28.13) The Cell Cycle and DNA Replication in Eukaryotes... 

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