User:Cocomonster0o/Chromosome jumping

Lead
''Chromosome jumping is a tool of molecular biology that is used in the physical mapping of genomes. It is related to several other tools used for the same purpose, including chromosome walking. Chromosome jumping is used to bypass regions difficult to clone, such as those containing repetitive DNA, that cannot be easily mapped by chromosome walking, and is useful in moving along a chromosome rapidly in search of a particular gene. 'Unlike chromosome walking, chromosome jumping is able to start on one point of the chromosome in order to traverse potential distant point of the same chromosome without cloning the intervening sequences.  The ends of a large DNA fragment is the target cloning section of the chromosome jumping while the middle section gets removed by sequences of chemical manipulations prior to the cloning step.'''

'''Chromosome jumping library differs from chromosome walking due to the manipulations executed before the cloning step. In order to construct the library of chromosome jumping, individual clones originate from random points in the genome (general jumping libraries first basic protocol) or from the termini of specific restriction fragments (specific jumping libraries alternate protocol) should be identified'''.

= Process = ''Chromosome jumping enables two ends of a DNA sequence to be cloned without the middle section. Genomic DNA may be partially digested using restriction endonuclease and with the aid of DNA ligase, the fragments are circularized. From a known sequence, a primer is designed to sequence across the circularized junction. This primer is used to jump 100 kb-300 kb intervals: a sequence 100 kb away would have come near the known sequence on circularization, it permits jumping and sequencing in an alternative manner. Thus, sequences not reachable by chromosome walking can be sequenced. Chromosome walking can be used from the new jump position (in either direction) to look for gene-like sequences, or additional jumps can be used to progress further along the chromosome.'' Combining chromosome jumping to chromosome walking through the chromosome allows bypassing repetitive DNA for the search of the target gene.

= Advantages and Disadvantages = The advantages of chromosome jumping are it allows more rapid movement through the genome compared to other techniques, such as chromosome walking; Secondly, it is able to travel across chromosomal regions containing unclonable sequences in bacterial hosts; Thirdly, this technique can be used to generate genomic markers with known chromosomal locations. ''' However, despite of these advantages, chromosome jumping is still restricted by the capacity of the cloning vector which is the distance of the ends of the two fragments which can be approximately hundreds of kilobases. Regardless, it is still deemed to be beneficial due to the possibility to jump over hundred kilobases in comparison to chromosome walking.'''

= Applications =

Genetic Disorders
'''Chromosome jumping library helps address the complication of standard cloning techniques with large molecular distances. Particularly for genetic disorders such as cystic fibrosis, it's gene is located in human chromosome 7, was able to utilize the chromosome jumping library to search for a jumping clone, met oncogene. This process allowed the possibility to use the chromosome jumping library for other genetic disorders that requires 100 kilobases jumps.'''