All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit

All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
All 3 structural genes lie on the same polycistronic mRNA and are expressed as a single unit. Such units are generally called operons (from operational units). The lac operon is only transcribed when lactose is present and the gene products are therefore needed. DNA: ....... Jacob and Monod proposed their model of regulation solely on the basis of genetic data derived from mutants. We will only talk about the model and not about the genetic data that led them to this model. Mutants showed that there are two distinctive DNA sequences that are necessary for
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: lac operon regulation (Fig. 6.8): • lac O (called operator , a non-coding DNA sequence that lies just downstream of the transcription start site) • lac I (a gene somewhere else on the chromosome that encodes a repressor protein called lac repressor ) With no lactose present : The lac repressor binds to the operator and blocks transcription. When lactose is present : lactose binds to the lac repressor, the repressor cannot bind the operator anymore and transcription is initiated....
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern