Question

Explain what forward genetics and reverse genetics are? Assume you have known the function of the gene A via genetic analysis, design some experiments using both forward and reverse genetics approaches to identify the gene X that may work in the same pathway as the gene A.

Answer 1

ANSWER )

Forward genetics allows the identification of mutants with phenotypes of interest and leads to the mechanistic understanding of biological processes.Forward genetics is an unbiased methodology to discover new genes or functions of genes.Forward genetic approach begins with a particular biological phenomenon or characteristic and asks, “Which genes are necessary to support this phenomenon?

Reverse genetics starts from a protein or DNA for which there is no genetic information and then works backward to make a mutant gene, ending up with a mutant phenotype. reverse genetics is a protein or a gene “in search of a function,” or, looked at another way, a protein or a gene “in search of a phenotype.” For example, a cloned wild-type gene detected by sequencing as an open reading frame (ORF) of unknown function can be subjected to some form of in vitro mutagenesis and reinserted back into the organism to determine the phenotypic outcome.

EXPERIMENTAL DESIGN

SUPPOSE WE HAVE TO IDENTIFY GENE X VIA REVERSE GENETICS

• X gene detected by sequencing as an open reading frame (ORF) of unknown function
• WHEN function not known ?---------------two approaches 1 ) in vitro Mutagenesis 2) gene disruption that is knock out
• observation of phenotype which may include X enzyme EXPRESSION OR STRUCTURE
• To validate the function reinsertion of X gene could reestablish the related wild type phenotype
• further compare the sequence with known gene could be used such as gene A in this case having known function that could help in identifying the protein structure and function.
• Another criteria can be used is the forward genetics where mutation in the gene A lead to particular mutant phenotype. This can be identify by sequencing that what is mutant allele that lead to mutant phenotype. further analysis of mutant protein sequence could indicate the function that had lead to mutant phenotype