Biomedical Engineering Reference
In-Depth Information
3
Jumping Ge ne Computational Approach
3.1 BiologicalBackground
3.1.1 biological Jumping gene Transposition
The.discovery.of.mobile.genetic.elements.in.chromosomes.has.a.long.history..
It.can.probably.date.back.to.the.1940s,.when.the.Nobel.Laureate.in.Physiology.
or.Medicine,.Barbara.McClintock,.studied.the.maize.chromosome..This.was.
even.earlier.than.when.the.double-helix.structure.of.deoxyribonucleic.acid.
(DNA).was.suggested.by.J..D..Watson.and.F..Crick.[62,63].
As.indicated.in.McClintock's.work.[8,14,33,34],.the.maize.chromosome.has.
two.parts.dissociated.from.each.other.and.always.breaks.at.a.certain.loca-
tion..It.was.later.found.that.this.phenomenon.is.caused.by.the.presence.of.
autonomous.and.the.nonautonomous.transposable.elements,.called.the.acti-
vator.(Ac).and.dissociator.(Ds),.respectively.
The.Ds.itself.is.stable..However,.with.the.presence.of.its.corresponding.Ac,.
the.Ds.will.move.and.consequently.introduce.the.breaking.of.a.chromosome,.
as.shown.in . FigureĀ 3.1 .. Such.a.gene.transposition.mechanism.also.results.in.
the.colorization.of.the.maize.kernels..The.transposition.of.the.Ds.in.different.
cells.is.random,.and.the.coloring.is.closely.related.to.the.stage.of.seed.devel-
opment.during.dissociation.and.the.number.of.Ac's.presented.
In.general,.the.transposable.elements.(called.transposons.or.jumping.genes,.
JGs).are.DNA.sequences.that.constitute.a.fraction.of.their.host.genome..They.
can.move.around.the.genome.via.the.transposition.processes.and.have.been.
identified.in.various.organisms,.including.prokaryotes.(e.g.,.bacteria).[23].as.
well.as.eukaryotes.(e.g.,.plants,.animals).[15].
The.JGs.can.be.divided.into.three.different.classes.based.on.their.modes.
of. transposition. [5,16,57].. The. class. I. JG. transposes. through. the. replication.
of.the.element.itself..First,.the.element.is.transcribed.into.a.ribonucleic.acid.
(RNA).intermediate..An.enzyme,.which.reverses.the.transcription.process,.
reversely.transcribes.the.RNA.into.DNA,.which.is.then.inserted.into.a.new.
chromosomal.position.
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