Gene Interactions
When the expression of a single trait is influenced by two or more different non-allelic genes, it is termed as genetic interaction. According to Mendel's law of inheritance, each gene functions in its own way and does not depend on the function of another gene, i.e., a single gene controls each of seven characteristics considered, but the complex contribution of many different genes determine many traits of an organism.
Gene Expression
Gene expression is a process by which the instructions present in deoxyribonucleic acid (DNA) are converted into useful molecules such as proteins, and functional messenger ribonucleic (mRNA) molecules in the case of non-protein-coding genes.
B -Galactosidase -- B - galactosidase belongs to class 3 ,hydrolases .B gal belongs to subclass of glycosylases with an oxygen substrate in nature.
E.coli encounters many different sugars in its environment . These sugars for example glucose and lactose require different enzymes for their metabolism .
Application -- B galactosidase assay is used frequently in genetics , molecular biology .
The production of it may be induced by non hydrolysable analog of allolactose IPGT which binds and releases the lac repressor from the lac operator , thereby allowing the initiation of transcription to proceed.
It is commonly used in molecular biology as reporter marker to monitor gene expression .Enzyme has two catalytic activities .
Hydrolyzes the disaccharide lactose to galactose plus glucose .
It converts lactose to another disaccharide allolactose which is a natural inducer for the lac operon .
IPGT ( Isopropyl Beta - D - 1 thiogalactopyranosidase ) --It is a molecular biology reagent .This compound is molecular mimic of allolactose , a lactose metabolite which triggers transcription of the lac operon and it is therefore used to induce protein expression where the gene is under the control of lac operator.
Operon -- An operon is a set of structural genes transcribed as a single messenger RNA and adjacent regulatory regions which control the expression of these genes .
Answer no 5 -- In the Absence of IPTG, lac operon --In the absence of IPTG or allolactose the lac gene JPOZY is transcribed and the resulting repressor protein binds to the operator site of lac operon .Olac and prevents transcription of lac Z ,lac Y ,lac J ,lac P genes.
In the presence of Inducers IPTG ,lac operon--In the presence of IPTG , during induction the inducer binds to repressor .
This causes a change in the conformation of the repressor which greatly reduces its affinity for the lac operator site .
The lac repressor now dissociates from the operator site and allows the RNA polymerase to begin transcribing the lac Z , lac Y ,genes .
Transcription to yield a single polycistronic mRNA which is then translated to produce all enzymes in large amount .
The existence of a polycistronic mRNA ensures that the amounts of all genes products are regulated coordinately .
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