replication

[‚rep·lə′kā·shən] (analytical chemistry) The formation of a faithful mold or replica of a solid that is thin enough for penetration by an electron microscope beam; can use plastic (such as collodion) or vacuum deposition (such as of carbon or metals) to make the mold. (cell and molecular biology) Duplication, as of a nucleic acid, by copying from a molecular template. (statistics) In experimental design, the repetition of an experiment or parts of an experiment to secure more data as an aid to determining the experimental error and to arrive at better estimates of the effects of various treatments with smaller standard errors. (virology) Multiplication of phage in a bacterial cell.

replication

the collection of data under the same conditions as a previous study. This is often done to test the VALIDITY of the conclusions drawn, since faults in design or analysis may thereby be discovered.

Replication

(also reduplication, autoreproduction, and autosynthesis), the process of the self-reproduction, or self-copying, of nucleic acids, genes, and chromosomes that occurs in all living cells. The mechanism of replication is based on the enzymatic synthesis of deoxyribonucleic acid (DNA) or ribo-nucleic acid (RNA), which occurs in accordance with the matrix principle.

The model of the structure of DNA—the double helix—was proposed in 1953 by J. Watson and F. Crick. This model both explained how genetic information is inscribed in a DNA molecule and made it possible to understand and experimentally study the chemical mechanisms of the duplication of genetic material. The strict specificity of the pairing of nitrogen bases in a DNA molecule is responsible for the complementarity of the sequences of bases in two chains and guarantees the precision of replication. The guanine-cytosine pair is stabilized by three hydrogen bonds, and the adenine-thymine pair is stabilized by two hydrogen bonds, thereby sharply diminishing the probability of the incorrect pairing of bases.

According to Watson and Crick, the process of DNA replication provides for the rupture of hydrogen bonds and the unwinding of the strands of a double helix; it also provides for the synthesis of complementary chains on solitary strands. As a result of DNA replication, two similar molecules arise from a single double-chain DNA molecule. In each daughter molecule there is one polynucleotide chain that is parental and one that is resynthesized (the semiconservative mechanism of replication).

DNA replication is a multistage genetically controlled process in which many enzymes participate, including DNA poly-merase, DNA ligase, and DNA methylase. The replication of DNA having a double chain has a fixed beginning and end and an oriented direction. The noncontinuous synthesis of new chains starts where the complementary chains of the parental DNA unwind (Figure 1).

Figure 1. Structure of the Y-fork proposed by the hypothesis of the noncontinuous replication of DNA

At the beginning of each synthesized segment of a DNA chain there is a priming strand of RNA that consists of 50–100 nucleotides. The fragments of the DNA chains, each containing about 1,000 nucleotides, gradually form on the RNA with the participation of DNA polymerase. The primer RNA is then destroyed by ribonuclease, while the synthesized DNA fragments are combined to form long chains by the enzyme polynu-cleotideligase.

Replication is unique in viruses and bacteriophages that have DNA composed of a single strand. DNA composed of a single chain [the (+)-chain] is introduced into the host cell, after which a complementary chain [the (–)-chain] is synthesized on the (+)-chain serving as a matrix. New single-chain (+)-chains, which form new viral particles, are synthesized on the double-helix molecule that has formed (the replicative form). Viruses and bacteriophages that contain RNA replicate by the same principle. Therefore, in all known cases of replication, DNA and RNA pass through a stage during which molecules have a double chain.

Eucaryotes are higher organisms whose cells contain a formed nucleus. The main genetic function in eucaryotes is performed by complex structures known as chromosomes, which consist of DNA, RNA, proteins, and other substances. The replication of DNA and other chromosomal components occurs during interphase, which precedes cell division. The doubled chromosomes subsequently disjoin and become evenly distributed between daughter cells. Thus, all hereditary information is transmitted relatively unchanged from cell to cell from one generation to the next.

REFERENCES

Watson, J. Molekuliarnaia biologiia gena. Moscow, 1967. (Translated from English.)
Ratner, V. A. Printsipy organizatsii i mekhanizmy molekuliarno-geneticheskikh protsessov. Novosibirsk, 1972.
Bresler, S. E. Molekuliarnaia biologiia. Leningrad, 1973.
Stent, G. Molekuliarnaia genetika. Moscow, 1974. (Translated from English.)

M. M. ASLANIAN

replication

(database, networking)Creating and maintaining a duplicatecopy of a database or file system on a different computer,typically a server. The term usually implies theintelligent copying of parts of the source database which havechanged since the last replication with the destination.

Replication may be one-way or two-way. Two-way replication ismuch more complicated because of the possibility that areplicated object may have been updated differently in the twolocations in which case some method is needed to reconcile thedifferent versions.

For example, Lotus Notes can automatically distributedocument databases across telecommunications networks. Notessupports a wide range of network protocols including X25and Internet TCP/IP.

Compare mirror. See also rdist.

replication

In database management, the ability to keep distributed databases synchronized by routinely copying the entire database or subsets of the database to other servers in the network.

There are various replication methods. Primary site replication maintains the master copy of the data in one site and sends read-only copies to the other sites. In a workflow environment, the master copy can move from one site to another. This is called "shared replication" or "transferred ownership replication." In symmetric replication, also called "update-anywhere" or "peer-to-peer replication," each site can receive updates, and all other sites are then updated. Failover replication, or hot backup, maintains an up-to-date copy of the data at a different site for backup. See mirroring, disaster recovery and distributed database.

replication

Related to replication: DNA replication

Replication

In Common-Law Pleading, the response of a plaintiff to the defendant's plea in an action at law, or to the defendant's answer in a suit in Equity.

Common-law Pleading required the plaintiff to set out the claim in a declaration or, in equity, in a bill. The defendant responded with a plea or answer. When the defendant raised a new point in his or her response, the plaintiff was required to introduce an additional fact that defeated this new point. The plaintiff had an opportunity to respond in a paper called a replication. The modern equivalent is known as the reply.

replication

in reply. Evidence in replication is evidence allowed after the other side has said something but when the party seeking to lead in replication has already had its proper say, an example being where something new emerges in re-examination that was not covered in cross-examination.

REPLICATION, pleading. The plaintiff's answer to the defendant's plea.
2. Replications will be considered, 1. With regard to their several kinds. 2. To their form. 3. To their qualities.
3.-Sec. 1. They are to pleas in abatement and to pleas in bar.
4.-1. When the defendant pleads to the jurisdiction of the court, the plaintiff may reply, and in this case the replication commences with a statement that the writ ought not to be quashed, or that the court ought not to be ousted of their jurisdiction, because &c., and concludes to the country, if the replication merely deny the subject-matter of the plea. Rast. Entr. 101 Thomps. Entr. 2; Clift's Entr. 17; 1 Chit. Pl. 434. As a general rule, when the plea is to the misnomer of the plaintiff or defendant, or when the plea consists of matter of fact which the plaintiff denies, the replication may begin without any allegation that the writ or bill ought not to be quashed. 1 Bos. & Pull. 61.
5.-2. The replication is, in general, governed by the plea, and most frequently denies it. When the plea concludes to the country, the plaintiff must, in general, reply by adding a similiter; but when the plea concludes with a verification, the replication must either, 1. Conclude the defendant by matter of estoppel; or, 2. May deny the truth of the matter alleged in the plea, either in whole or in part; or, 3. May confess and avoid the plea; or, 4. In the case of an evasive plea, may new assign the cause of action. For the several kinds of replication as they relate to the different forms of action, see 1 Chit. Pl. 551, et seq.; Arch. Civ. Pl. 258.
6.-Sec. 2. The form of the replication will be considered with regard to, 1. The title. 2. The commencement. 3. The body. 4. The conclusion.
7.-1. The replication is usually entitled in the court and of the term of which it is pleaded, and the names of the plaintiff and defendant are stated in the margin, thus "A B against C D." 2 Chit. Pl. 641.
8.-2. The commencement is that part of the replication which immediately follows the statement of the title of the court and term, and the names of the parties. It varies in form when it replies to matter of estoppel from what it does when it denies, or confesses and avoids the plea; in the latter case it commences with an allegation technically termed the preclude non. (q.v.) It generally commences with the words, "And the said plaintiff saith that the said defendant," &c. 1 Chit. Pl. 573.
9.-3. The body of the replication ought to contain either. 1. Matter of estoppel. 2. Denial of the plea. 3. A confession and avoidance of it; or, 4. In case of an evasive plea, a new assignment. 1st. When the matter of estoppel does not appear from the anterior pleading, the replication should set it forth; as, if the matter has been tried upon a particular issue in trespass, and found by the jury, such finding may be replied as an estoppel. 3 East, R. 346; vide 4 Mass. R. 443. 2d. The second kind of replication is that which denies or traverses the truth of the plea, either in part or in whole. Vide Traverse, and 1 Chit. Pl. 576, note a. 3d. The third kind of replication admits, either in words or in effect, the fact alleged in the plea, and avoids the effect of it by stating new matter. If, for example, infancy be pleaded, the plaintiff may reply that the goods were necessaries, or that the defendant, after he came of full age, ratified and confirmed the promise. Vide Confession and Avoidance. 4th. When the plea is such as merely to evade the allegation in the declaration, the plaintiff in his replication may reassign it. Vide New Assignment, and 1 Chit. Pl. 601.
10.-4. With regard to the conclusion, it is a general rule, that when the replication denies the whole of the defendant's plea, containing matter of fact, it should conclude to the country. There are other conclusions in particular cases, which the reader will find fully stated in 1 Chit. Pl. 615, et seq.; Com. Dig. Pleader, F 5 vide 1 Saund. 103, n.; 2 Caines' R. 60 2 John. R. 428; 1 John. R. 516; Arch. Civ. Pl. 258; 19 Vin. Ab 29; Bac. Ab. Trespass, I 4; Doct. Pl. 428; Beames' Pl. in Eq. 247, 325, 326.
11.-Sec. 3. The qualities of a replication are, 1. That it must answer so much of the defendant's plea as it professes to answer, and that if it be bad in part, it is bad for the whole. Com. Dig. Pleader, F 4, W 2; 1 Saund. 338; 7 Cranch's Rep. 156. 2. It must not depart from the allegations in the declaration in any material matter. Vide Departure, and 2 Saund. 84 a, note 1; Co. Lit. 304 a. See also 3 John. Rep. 367; 10 John. R. 259; 14 John., R. 132; 2 Caines' R. 320. 3. It must be certain. Vide Certainty. 4. It must be single. Vide U. S. Dig. Pleading, XI.; Bouv. Inst. Index, h.t.; Duplicity; Pleadings.

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Synonyms for replication

noun something closely resembling another

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Synonyms for replication

noun the act of making copies

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noun (genetics) the process whereby DNA makes a copy of itself before cell division

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noun a quick reply to a question or remark (especially a witty or critical one)

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noun (law) a pleading made by a plaintiff in reply to the defendant's plea or answer

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noun the repetition of a sound resulting from reflection of the sound waves

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noun copy that is not the original

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noun the repetition of an experiment in order to test the validity of its conclusion

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