Users' questions

What does exon shuffling do?

What does exon shuffling do?

Exon shuffling is a molecular mechanism for the formation of new genes. It is a process through which two or more exons from different genes can be brought together ectopically, or the same exon can be duplicated, to create a new exon-intron structure.

Does exon shuffling occur in humans?

As exons occupy only 1% of the human genome and introns about 24%, by far most of the crossovers occur between exons, rather than inside. The natural process of creating new combinations of exons by intronic recombination is called exon shuffling.

What is a potential benefit of exon shuffling?

What is the potential benefit of exon shuffling? The potential benefit of exon shuffling is that exons can recombine to create novel proteins. The biggest problem with the shotgun technique is its tendency to underestimate the size of the genome.

How does exon shuffling increase diversity?

A. This kind of exon shuffling could happen when short DNA sequences in two different introns misalign during meiotic synapsis, allowing for unequal crossing over. Expression of a gene with a ‘new’ exon produces a protein with a new domain and a new activity. If the event is not harmful, diversity is increased!

How does domain shuffling occur?

Another process by which a new domain can be acquired is by the insertion of a sequence from one gene into another by recombination. The process is termed domain shuffling. One way in which this occurs is through the shuffling of exons (again through insertion, duplication, or deletion).

How does DNA shuffling work?

DNA shuffling involves the digestion of a gene by DNaseI into random fragments, and the reassembly of those fragments into a full-length gene by primerless PCR: the fragments prime on each other based on sequence homology, and recombination occurs when fragments from one copy of a gene anneal to fragments from another …

What is domain shuffling?

Domain shuffling is a phenomenon where the gene segments coding for functional domains are shuffled between different genes during evolution. The boundaries between different domains may or may not correspond to the intron-exon boundaries of the encoding gene.

What is Domain duplication?

Duplicated domains allow pleiotropically expressed proteins to evolve new functions without disrupting existing interaction networks. Human missense sequence variants reside within evolutionarily conserved domains, likely disrupting protein function.

What’s an example of a silent mutation?

Silent mutations are base substitutions that result in no change of the amino acid or amino acid functionality when the altered messenger RNA (mRNA) is translated. For example, if the codon AAA is altered to become AAG, the same amino acid – lysine – will be incorporated into the peptide chain.

How do you knock down gene expression?

RNA interference (RNAi) is a means of silencing genes by way of mRNA degradation. Gene knockdown by this method is achieved by introducing small double-stranded interfering RNAs (siRNA) into the cytoplasm. Small interfering RNAs can originate from inside the cell or can be exogenously introduced into the cell.

What are the two types of gene shuffling?

Two different processes contribute to gene shuffling: independent assortment and crossing over. During meiosis I, homologous chromosomes pair up with each other.

Which is an example of the importance of exon shuffling?

A concrete example of how exon shuffling is physiologically crucial. The immunoglobulin genes of undifferentiated carries broad coding capacity. But through deletions and rearrangements of the gene as B lymphocytes differentiate, considerable functional diversity can be conferred.

How are exons shuffled to generate new proteins?

The exons from an original gene can be recombined such that one exon is missing in each novel construct. The new genes are then screened for new or altered function. Another shuffling technique to generate novel proteins is to use premade protein modules.

How is a combinatorial library generated in exon shuffling?

In the exon shuffling approach, a combinatorial library is generated from an already existing eukaryotic gene. Each of the exons of the eukaryotic gene is generated by a separate PCR reaction. The segments are then mixed and reassembled by overlap PCR.

How are retrotransponsons used in exon shuffling?

Retrotransponsons synthesize a cDNA copy based on the RNA strand using a reverse transcriptase related to retroviral RT. The cDNA copy is then inserted into new genomic positions to form a retrogene. This mechanism has been proven to be important in gene evolution of rice and other grass species through exon shuffling.