Gene amplification refers to a number of natural and artificial processes by which the number of copies of a

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

is increased "without a proportional increase in other genes".

Artificial DNA amplification

In research or diagnosis DNA amplification can be conducted through methods such as: *

Polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) t ...

, an easy, cheap, and reliable way to repeatedly replicate a focused segment of DNA by polymerizing nucleotides, a concept which is applicable to numerous fields in modern biology and related sciences. *

Ligase chain reaction The ligase chain reaction (LCR) is a method of DNA amplification. The ligase chain reaction (LCR) is an amplification process that differs from PCR in that it involves a thermostable ligase to join two probes or other molecules together which can t ...

, a method that amplifies the nucleic acid used as the probe. For each of the two DNA strands, two partial probes are ligated to form the actual one; thus, LCR uses two enzymes: a

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create ...

(used for initial template amplification and then inactivated) and a thermostable

DNA ligase DNA ligase is a specific type of enzyme, a ligase, () that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. It plays a role in repairing single-strand breaks in duplex DNA in living organ ...

. *

Transcription-mediated amplification Transcription-mediated amplification (TMA) is an isothermal (does not change the nucleic acid temperature), single-tube nucleic acid amplification system utilizing two enzymes, RNA polymerase and reverse transcriptase. "Amplification" means crea ...

, an isothermal, single-tube

nucleic acid Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main cl ...

amplification system utilizing two enzymes,

RNA polymerase In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template. Using the enzyme helicase, RNAP locally opens the ...

and reverse transcriptase, to rapidly amplify the target RNA/DNA, enabling the simultaneous detection of multiple pathogenic organisms in a single tube.

Natural DNA amplification

DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...

is a natural form of copying DNA with the amount of genes remaining constant. However, the amount of DNA or the number of genes can also increase within an organism through gene duplication, a major mechanism through which new genetic material is generated during

molecular evolution Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics ...

. Common sources of gene duplications include

ectopic recombination Ectopic recombination is an atypical form of recombination in which crossing over occurs at non-homologous, rather than along homologous, loci. //This needs to be edited, as it is 1)incorrect and 2)contradicts what's written below, namely the ne ...

retrotransposition A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Trans ...

event,

aneuploidy Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any ...

polyploidy Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

, and

replication slippage Replication may refer to: Science * Replication (scientific method), one of the main principles of the scientific method, a.k.a. reproducibility ** Replication (statistics), the repetition of a test or complete experiment ** Replication crisis * ...

. A piece of DNA or

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

that is the source and/or product of either natural or artificial amplification or replication events is called an

amplicon In molecular biology, an amplicon is a piece of DNA or RNA that is the source and/or product of amplification (molecular biology), amplification or DNA replication, replication events. It can be formed artificially, using various methods including ...

.Graham Dellaire, Jason N Berman, Robert J. Arceci, eds., ''Cancer Genomics: From Bench to Personalized Medicine'' (2014), p. 205.

References

{{Repeated sequence Molecular genetics