Transposable Elements: Jumping Genes

1211 Words 5 Pages
Saibhuvaneswari
RA1611014010048
JUMPING GENES
Transposable elements (TEs), also known as "jumping genes" or transposons, are sequences of DNA that move (or jump) from one location in the genome to another.
A transposable element (TE or transposon) is a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transposition often results in duplication of the TE.
The transposable elements make the biggest part of the genome. It mainly contributes to the mass of the Eukaryotic cell DNA. They are mainly used in the study of genome function, evolution and to alter the DNA.
DISCOVERY:
The Jumping genes were first discovered by an American scientist,
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McClintock studied-the variegated colour pattern of maize kernels-involves three alleles rather than the usual two. McClintock worked with what is known as the Ac/Ds system in maize, which she discovered by conducting standard genetic breeding experiments with an unusual phenotype. Through these experiments, McClintock recognized that breakage occurred at specific sites on maize chromosomes. Indeed, the first transposable element she discovered was a site of chromosome breakage, aptly named "dissociation" (Ds). Although McClintock eventually found that some TEs can "jump" autonomously, she initially noted that the movements of Ds are regulated by an autonomous element called "activator" (Ac), which can also promote its own transposition. Of course, these discoveries were preceded by extensive breeding experimentation. The behaviour of kernel colour alleles was revolutionary in its proposition that genomic replication does not always follow a consistent pattern. Indeed, as a result of both autonomous and activator-controlled transposition at different stages of seed development, the genes of maize kernels are capable of producing a variety of coloration …show more content…
The double-stranded IR region separates a large circular loop from the small “lollipop” loop. An explanation at the nucleotide level for the lollipop structure. Transposons are stretches of DNA that have repeated DNA segments at either end. A transposon consists of a central sequence that has transposes gene and additional genes. This is flanked on both sides by short repeated DNA segments. The repeated segments may be direct repeats or inverted repeats. This terminal repeats help in identifying transposons. The number of repeated nucleotides is uneven 5 or 7 or 9 nucleotides are due to its method of insertion at the target

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