CIS-TRANS OR Complementation Test,Cis,Trans,Protaplasm,Chromosomes,Correlated Trans,Protoplasm,Cell,Heterozygote

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	CIS-TRANS OR Complementation Test -Complementation test is done to confirm the site of mutation In complementation test, using a known mutation as reference, an unknown mutation is identified. In this test, two mutations are placed in common protoplasm either is cis or trans configuration. The cis trans test provides an operational definition of the gene as the unit of function the unit controlling the synthesis of one polypeptide. CIS-test In this method, the two mutations are being examined in a common protoplasm in cis or coupling configuration, i.e., both the mutations will be on the same chromosomes. cis test is used to find whether a given mutation is in the mutation site/gene or it is in other site.
The cis test is an important control test, which establishes the validity of the correlated trans or complementation test. Trans test In this method, the two mutations that are being examined are placed in common protoplasm in trans or repulsion configuration, i.e., both the mutations are on different chromosomes. The concept of cis trans test functions is simple. If an unknown mutation occurs in a known gene mutation, then the test gives a negative result that is there will be no production of product or we will get an inactivated product.
If the unknown mutation does not occur in the known gene mutation site, then the test gives a positive result, that is, there will be production of product, because we know that there are two copies of the gene. If one gene is mutated, the other will supplement or code for the protein. As both the mutations are on different genes, the other gene will take the role of coding for the protein. In the case of a mutation which gives a negative result, there will be no production of protein as both the genes have mutation. In many cases, only the trans test is done to confirm the mutation site, since construction of a cis heterozygote is time consuming and expensive.
For the trans test, one known mutant animal or cell is crossed with unknown mutant animal or cell to get a diploid cell containing the two mutations in the trans or repulsion configuration and is called as trans heterozygote. The results of the trans test are totally uncontroversial, when mutations lead to the partial or total defective protein or total abolished product. This type of situation arises only when mutations are caused by deletions, frame shift mutations or chain termination mutations. The analysis becomes complicated when the mutations are caused by substitution involving different nucleotides, but no alteration in the amino acid charge, or volume of amino acid. The information provided by cis trans or complementation test is totally distinct from that obtained from recombination analyses.
	Complementation and recombination should not be confused. They are different and give different information. Recombination tells the relationship between two genes whereas complementation gives information about the mutation position. Even though the cis-trans test is a widely used and very helpful technique, it has some drawbacks.

1. It cannot be used when the mutations occur in dominant or co dominant genes.

2. It cannot be used for polar mutation analysis.

3. It cannot be used for understanding those genes which do not code for diffusible proteins or those which areused in regulatory mechanism.

4. It cannot be used for genes which code for a polypeptide which integrates into a complex protein or which forms dimers.

Complex Genes
Pseudogenes
Overlapping Genes
Nested Genes
CIS - TRANS OR Complementation Test
Structure of R II Genes
Deletion Mapping
Electron Microscope Heteroduplex Mapping