How the Operon Works

How the Operon Works

Length: 608 words (1.7 double-spaced pages)

Rating: Excellent

Open Document

Essay Preview

More ↓
How the Operon Works

The operon is a set of coding regions of DNA clustered together that includes structural genes and it is under the control of a single regulatory region. The operator regulates transcription, which is a repressor protein. When the operator binds to a segment of the regulatory region, transcription is shut down.
E. Coli will be used as an example of how an inducible operon works. E. Coli's main source of nutrition is glucose. If glucose is not available, it can utilize lactose. But the necessary enzymes used to digest lactose aren't normally made by E. Coli. When lactose is available in the environment, certain activities will take place allowing E. Coli to digest lactose. Lactose induces transcription of enzymes to utilize lactose.
It takes three enzymes for E. Coli to digest lactose: beta-glycosidase, permease, and transacetylase. The coding regions for these three enzymes are linked together under the control of a single regulatory region called the lac operon.
The I gene makes the lac repressor protein. The I gene constitutively transcribes mRNA for the repressor protein. The repressor is a regulator protein. It can bind to either lactose or the operator DNA. The binding of a repressor protein to either DNA or lactose is reversible, so the repressor is bound most often to whichever of the two it finds in the highest concentration. The lac repressor protein is highly attracted to the operator sequence of the lac promoter. When it is bound, transcription does not occur. If lactose levels rise to high concentrations, the lactose molecules will quickly bind to a lactose molecule rather than the one operator. The operator would no longer be repressed and transcription will proceed.
The coding region of the lac operon is transcribed as a single polycistronic mRNA. When the three lactose-digesting enzyme are available, they will digest the lactose. Lactose levels will go down and the repressor molecule will bind to the operator when there is no more lactose to metabolize. Also as the availability of lactose gets low, the lactose molecules that were bound to repressor molecules can be degraded. This frees up repressor molecules. When the enzymes are no longer needed, transcription is shut down.
Lactose alone cannot induce the lac operon. E. Coli prefers to utilize glucose rather than lactose because glucose is simpler and more abundant.

How to Cite this Page

MLA Citation:
"How the Operon Works." 11 Nov 2019

Need Writing Help?

Get feedback on grammar, clarity, concision and logic instantly.

Check your paper »

Inducible Operon vs Repressible Operon Essay

- Inducible Operon vs Repressible Operon Genetic regulation is a process where certain proteins and other kinds of stimuli tend to cause a cell to express genes or not express them. The bacteria cell system is small system, but it carries out a lot of activities and must do so economically and efficiently, therefore actions of these genes must be regulated. There are two types of regulatory systems: inducible and repressible An operon is a cluster of genes that work together to form a polycistronic mRNA....   [tags: Papers]

Free Essays
529 words (1.5 pages)

Essay on Literary Works and the History They Tell

- Conventionally when one thinks of history they think of the facts that are written in textbooks and learned in history class. People recall specific dates, who was involved, why it happened, and exactly what the events were. Usually the only questions that are thought of are the five journalistic questions. People often forget that that same history in textbooks was recorded by one person and may not tell everything that happened in that event. For a person really become knowledgeable on a particular event in history they should explore all possible avenues recorded history about that event....   [tags: literary works, history, novels]

Research Papers
3339 words (9.5 pages)

The legendary Works of F. Scott Fitzgerald Essay

- An Analytical perspective of the great works of F. Scott Fitzgerald The legendary Works of F. Scott Fitzgerald reflects onto his readers and exceptional childhood and educational background emmating from his life experiences. It is believed The Great Gatsby reflects his point of view of his fortunate life as an author. F. Scott Fitzgerald is an author of many short stories and novels in Americas history primarily however his works explimfied the era of the nineteen twenties. Fitzgerald was born on September 28th 1896 into an upper middle class family living in Saint Paul Minnesota....   [tags: great gatsby, great works]

Research Papers
1168 words (3.3 pages)

Evils of Monarchy and Society in the Works of Mark Twain Essay

- The Evils of Monarchy and Society in the Works of Mark Twain       In the latter part of his life, Mark Twain developed a deep-rooted hatred for society.  His aphorisms often reflect this contempt: "Every one is a moon and has a dark side which he shows to no one" (Salwen n.pag.).  This disdain for humanity eventually seated itself in complete disapproval for what he called the "damned human race."  Twain's criticism for society appeared in many of his works, growing stronger and stronger as time passed.  Hand in hand with his distaste for society went his hatred for the upper class.  In each of his works, Twain creates a theme of appearance versus reality and ultimately brings out his...   [tags: Works of Mark Twain]

Research Papers
2350 words (6.7 pages)

Michael Ondaatje's The Collected Works of Billy the Kid Essay

- The Perception of Violence in Michael Ondaatje's The Collected Works of Billy the Kid A question that arises in almost any medium of art, be it music, film or literature, is whether or not the depiction of violence is merely gratuitous or whether it is a legitimate artistic expression. There can be no doubt that Michael Ondaatje's long poem The Collected Works of Billy the Kid is a violent work, but certain factors should be kept in mind before passing it off as an attempt to shock and titillate; certainly, the poem does both of these, but they are not the primary purpose of the work....   [tags: Collected Works Billy Kid]

Research Papers
2721 words (7.8 pages)

The Works of A. A. Milne Essay

- Although an extremely successful playwright author, talented poem author, and a superb novelist in his early years of writing, A. A. Milne is known around the world because of his highly treasured children’s book series, Winnie-the-Pooh. Milne’s love for writing and words started at a young age, but he didn’t pursue this career path until after graduating from Cambridge with a degree in mathematics according to S. Ward (9). Milne was able to relate to the young readers of his children’s books, as well as give a sort of distinguished outlook with the parents and adult readers....   [tags: Winnie-the-Pooh]

Research Papers
1359 words (3.9 pages)

The Works of Magritte Essay examples

- Rene Magritte was an enigmatic and strange man who painted surrealism paintings. Little is known about his childhood except that his mother, Regine Magritte took her own life by drowning herself in the Sambre river. Young Magritte is thought to have discovered her body floating with her night garment covering her face. There is speculation that this trauma was an influence on many of Magritte’s works. When Rene Magritte took up his brushes, he created beautiful visual riddles that delight and bewilder the viewer....   [tags: Art]

Research Papers
1789 words (5.1 pages)

The Works of Archimedes Essay

- Archimedes was a Greek mathematician who created multiple inventions, formed new mathematical techniques, and made advances in geometry that we use in everyday mathematics. Regarded as one of the utmost mathematicians of all time (“Archimedes c.287 B.C.-212 B.C.”), he is responsible for improving the arithmetical meaning of infinity and how we use mathematical models in the real world (Noel 28). He opened many doors in the world of geometry and math, making very important contributions to modern civilization....   [tags: biography, history, physics]

Research Papers
987 words (2.8 pages)

Life and Works Essay

- Life and Works Who is Leonardo Da Vinci. Leonardo had a keen eye and quick mind that led him to make important scientific discoveries, yet he never published his ideas. He was a gentle vegetarian who loved animals and despised war, yet he worked as a military engineer to invent advanced and deadly weapons. He was one of the greatest painters of the Italian Renaissance, yet he left only a handful of completed paintings. It may seem unusual to include Leonardo da Vinci in a list of paleontologists and evolutionary biologists....   [tags: Essays Papers]

Research Papers
863 words (2.5 pages)

Essay on Plato's Works

- Plato's Works In his works, Plato writes about truth, justice, and reality in full detail. His ideas are greatly deep and persuasively argued. It is from him that all western philosophy is a footnote. He describes his view in a series of numerous dialogues. For my report, I have chosen four of his works to study, which I think were his most important. "The Republic" is a dialogue composed of 10 books. The theme in its entirety is justice. The characters of the dialogue are Socrates, who is the narrator; Glaucon and Adeimantus, brothers of Plato; Cephalus, a rich old man; Polemarchus, son of Plato; Thrasymachus, a Sophist; and Cleitophon....   [tags: Papers]

Research Papers
1893 words (5.4 pages)

The bacterium does not want to waste energy making lactose-metabolizing enzymes when there is plenty of glucose present. The lac operon should be induced only when there is lactose present and no glucose at all.
The lac promoter by itself binds poorly to RNA polymerase. So even if the repressor is not bound to the operator, transcription does not readily occur. Therefore the presence of lactose alone does not induce transcription. When catabolite activator protein of CAP, an accessory protein binds to the promoter it stimulates the interaction of RNA polymerase and transcription. CAP binds to the promoter only when there is no glucose in the environment. When glucose levels are low, there is an increase in the level of cyclic AMP or camp, which is metabolic derivative of ATP. cAMP binds to CAP and then Cap binds to the lac promoter and transcription is stimulated. The lac operon will be transcribed only when lactose is present and there in no glucose.
With a repressible operon we need a situation where the products of an operon are normally needed, and only under unusual circumstances would the operon need to be shut down. E coli normally has to make its own tryptophan. Tryptophan is rarely found in the environment. The biosyntheticf pathway for the production of tryptophan consists of five enzymatic steps. The coding regions for each other the enzymes in the pathway are located within the operon. The promoter of the trp operon is highly attracted to RNA polymerase. No additional protein is needed to transcribe the operon. The operon is constitutively transcribed. If tryptophan is present in the environment, the bacterium will inactivate the operon and utilize the free tryptophan.
The trp repressor is incapable of binding to the trp operator itself. But when there is free trptophan around, the tryptophan acts as a co-repressor. It binds to the trp repressor and forms a repressor complex. This complex binds to the operator and shuts down transcription.
If tryptophan levels decline, the repressor is less likely to be found to a tryptophan molecule. The operator is freed and transcription continues again.
Bacteria have complex methods to regulator the expression of certain genes. The operon shows that even though bacteria may seem like simple organism, they have evolved complex systems that have allowed them to survive for billions of years.
Return to