Genetics going forward is the genetic base determining approach that is responsible for the phenotype. This was initially done by using natural mutations or inducing mutants with radiation, chemicals, or insertional mutagenesis (eg transposable elements). The next breeding takes place, the mutant individual is isolated, and then the gene is mapped. Future genetics can be considered as a counter to reverse genetics, which determines the function of genes by analyzing the phenotypic effects of altered DNA sequences. The mutant phenotype is often observed long before it has the idea of ​​which genes are responsible, which can cause genes to be named their mutant genotype (eg Drosophila reddish named after eye color in the mutant).
Video Forward genetics
General techniques
Often hundreds of thousands of mutations are generated. Chemicals such as ethylmethanesulfonate (EMS) cause random point mutations. These types of mutagens can be useful because they are easy to apply to any organism but they can be very difficult to map. Mutations can also be generated by inserti- tional mutagenesis. For example, transposable elements containing markers are mobilized into the genome randomly. These transposons are often modified for transpose only once, and once incorporated into the genome, selectable markers can be used to identify mutated individuals. Because these known DNA fragments inserted can make mapping and cloning of genes much easier. Other methods such as using radiation to cause removal and rearrangement of chromosomes can be used to produce mutants as well.
Once mutated and filtered, a complement testing is usually performed to ensure that the mutant phenotype arises from the same genes if the mutation is recessive. If the progeny after a cross between two recessive mutants has a wild-type phenotype, then it can be concluded that the phenotype is determined by more than one gene. Usually, alleles that show the strongest phenotype are further analyzed. A genetic map can then be made using relationships and genetic markers, and then the desired genes can be cloned and sorted. If many of the same gene alleles are found, the screen is said to be saturated and it is likely that all the genes involved result in a phenotype being discovered.
Maps Forward genetics
Human disease
Prior to 1980 the very few human genes had been identified as locus disease until advances in DNA technology gave rise to cloned positions and reverse genetics. Finding disease loci using old advanced genetic techniques is a very long and difficult process and a lot of work goes into mapping and cloning genes through association studies and running chromosomes. However, cystic fibrosis shows how advanced genetic processes can account for human genetic disorders. A genetic association study was able to map the disease locus in cystic fibrosis to chromosome 7 using a protein marker. After that, chromosomes run and jump techniques are used to identify genes and sequence them. Future genetics can work for single single-gen-phenotype situations but in more complicated diseases such as cancer, on the contrary genetics are often used.
Classic classical genetics
With a classical genetic approach, a researcher will then search for genes on his chromosome by intercrossing individuals with other unusual features and collecting statistics about how often they are inherited together. Classical geneticists will use phenotypic properties to map new mutant alleles. Finally the expectation is that such a screen will reach a considerable scale so that most or all of the newly generated mutations will become the second hit of the locus, essentially saturating the genome with mutations. This type of mutation mutation in this classical experiment is used to determine the minimal set of genes for the emergence of a specific phenotype. However, such early screens are incomplete because they lose excess locus and epigenetic effects, and such screens are difficult to do for certain phenotypes that do not have a measurable phenotype directly. In addition the classical genetic approach takes longer.
References
See also
- Inverted genetics
- Classic genetics
Source of the article : Wikipedia