What is true about lac operon?
What is true about 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.
Which of the following statements about lac operon in E coli is true?
Which of the following statements about lac operon in e. coli is true? Explanation: Bacterial genes are polycistronic and genes in eukaryotes are monocistronic. Explanation: CBP interacts with the basal transcription complex and activates transcription.
Which of the following is the true inducer of the lac operon?
allolactose
What is the lac operon quizlet?
Lac Operon. a segment of DNA , under the control of the same promoter, found in some prokaryotes allowing for regulation over protein synthesis. Promoter. specific segment of DNA that binds with RNA Polymerase to begin transcription of mRNA from the operon genes.
Is the lac operon positive or negative?
The lac operon is a negatively controlled inducible operon, where the inducer molecule is allolactose. In negative repressible operons, transcription of the operon normally takes place. Repressor proteins are produced by a regulator gene, but they are unable to bind to the operator in their normal conformation.
What is the basic function of the lac operon quizlet?
What is the basic function of the lac operon? A- To code for enzymes involved in synthesizing lactose.
What is the function of the lac operator quizlet?
The lac operon is on or induced when allolactose is bound to the lac I repressor protein, allowing transcription to be activated to high levels. When allolactose is not bound, lac I is recruited to the lac operator, blocking RNA polymerase from transcribing the gene.
What is the function of the lac repressor system in E coli?
The Lac repressor protein, LacI, prevents the transcription of genes involved in lactose utilization (lac genes) in E. coli. Like many other repressors, LacI utilizes multiple operators to increase the efficiency of repression.
What is the lac operon in prokaryotes?
The lac Operon: An Inducer Operon A major type of gene regulation that occurs in prokaryotic cells utilizes and occurs through inducible operons. The lac operon encodes the genes necessary to acquire and process the lactose from the local environment, which includes the structural genes lacZ, lacY, and lacA.
How many types of lac operon are there?
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 lac operon and why is it important?
The classic example of prokaryotic gene regulation is that of the lac operon. This operon is a genetic unit that produces the enzymes necessary for the digestion of lactose (Fig. 16-13). The lac operon consists of three contiguous structural genes that are transcribed as continuous mRNA by RNA polymerase.
What is positive regulation of lac operon?
The association between RNA polymerase and DNA is enhanced when the CAP-cAMP complex is present. Enhanced RNA polymerase binding leads to a high rate of transcription and translation of the lac operon structural genes lacZ, lacY, and lacA. The protein products of lacZ, lacY, and lacA metabolize lactose into glucose.
What is the difference between positive and negative regulation?
The main difference between positive and negative gene regulation is that in the positive gene regulation, genes undergo transcription whereas, in the negative gene regulation, the gene expression is normally blocked.
How the presence of glucose will affect expression of the Ara operon?
In the presence of glucose, the concentration of cAMP declines, preventing CAP binding and thereby decreasing the expression of the Lac operon.
How is the lac operon affected by negative control quizlet?
lac operon is under negative control by a repressor protein (because once bound the lac repressor prevents RNA polymerase from transcribing the lacZ, lacY, and lacA genes. lac operon is under positive control by an activator protein, the catabolite activator protein (CAP).
How is the lac operon affected by negative control?
Explanation: The lac operon exhibits both systems. It is a negative control system because expression is typically blocked by an active repressor (the lac repressor) that turns off transcription. The lac repressor binds to the operator region and negatively controls (prevents) transcription.
How long is the lac operon expressed in presence of lactose?
The Lactose operon expresses as long as the Lactose is present. When all lactose is converted into glucose and galactose, the reaction stops.
Which is an example of negative regulation?
Repressor binding blocks RNA polymerase from binding with the promoter, thereby leading to repression of operon gene expression. A classic example of negative repressible regulation of gene expression involves the trp operon, which is regulated by a negative feedback loop.