What is the correct sequence of genes in lac operon?
The lac operon consists of three structural genes: lacZ, which codes for β-galactosidase, which acts to cleave lactose into galactose and glucose; lacY, which codes for lac permease, which is a transmembrane protein necessary for lactose uptake; and lacA, which codes for a transacetylase that transfers an acetyl group …
What is the sequence of lac promoter?
The lactose (lac) operon promoter is positively regulated by the catabolite gene activator-cyclic AMP complex (CAP) that binds to the DNA located 61.5 bp upstream of the transcription start site. Between the CAP binding site and the core promoter sequence is a 13-bp sequence (from -38 to -50 [the -45 region]).
What is coded by I gene and Y gene of lac operon?
Complete step by step answer: The Lac-operon consists of three structural genes that code for different enzymes. The i gene is the one coding for the Repressor protein. The y gene is which codes for permease enzyme and facilitates and regulates the permeability of lactose into the cells.
What are the 4 components of the lac operon?
The various components of lac operon are regulator gene, promoter gene, operator gene and structural genes. Regulatory genes synthesize a chemical called repressor which combine with operator gene to switch off the operon.
What is the correct sequence of steps for gene expression?
The correct answer is (A) Initiation, Elongation, Termination. Transcription produces a molecule of mRNA from a gene sequence in DNA. This process…
Why is lac operon inducible?
Allolactose is an example of an inducer, a small molecule that triggers expression of a gene or operon. The lac operon is considered an inducible operon because it is usually turned off (repressed), but can be turned on in the presence of the inducer allolactose.
How long will the lac operon be expressed?
Lac operon expresses as long as lactose is present. When all the lactose is converted into glucose and galactose, the reaction stops.
What is the role of lac Z?
lacZ encodes an enzyme that splits lactose into monosaccharides (single-unit sugars) that can be fed into glycolysis. Similarly, lacY encodes a membrane-embedded transporter that helps bring lactose into the cell.
What will be the correct gene expression pathway?
Gene expression pathway is : Gene – transcription – mRNA – translation – protein.
What is the structure of lac operon?
The lac operon consists of 3 structural genes, and a promoter, a terminator, regulator, and an operator. The three structural genes are: lacZ, lacY, and lacA. lacZ encodes β-galactosidase (LacZ), an intracellular enzyme that cleaves the disaccharide lactose into glucose and galactose.
What is the function of the genes in the lac operon?
The lac operon is an operon, or group of genes with a single promoter (transcribed as a single mRNA). The genes in the operon encode proteins that allow the bacteria to use lactose as an energy source.
Why is the lac operon said to be an inducible operon?
Lac operanon is said to be an inducible operon because when allolactose is present, it induces the inactivation of the lac repressor.
What are the proteins produced by the lac operon?
The proteins are not produced by the bacterium when lactose is unavailable as a carbon source. The lac genes are organized into an operon; that is, they are oriented in the same direction immediately adjacent on the chromosome and are co-transcribed into a single polycistronic mRNA molecule.
What are the genes of an operon?
The DNA of the operon contains three genes, Gene 1, Gene 2, and Gene 3, which are found in a row in the DNA. They are under control of a single promoter (site where RNA polymerase binds) and they are transcribed together to make a single mRNA that has contains sequences coding for all three genes.