Lectures

Prokaryotic Gene Expression

by Georgina Cornwall, PhD
(1)

Questions about the lecture
My Notes
  • Required.
Save Cancel
    Learning Material 2
    • PDF
      Slides 10 GeneRegulationProteins Genetics.pdf
    • PDF
      Download Lecture Overview
    Report mistake
    Transcript

    00:00 versus monocistronic of course leads to different regulatory mechanisms.

    00:00 First we will look at the prokaryotic system because naturally it is a little bit simpler and gives us a great place to springboard from and look at eukaryotic regulation. Prokaryotic gene expression is primarily regulated at the level of transcription and this makes sense because that is where the most players are involved are also prokaryotic cells, not having a nucleus to separate transcription from translation need to take care of it at that transcriptional level and then we know the ribosomes jump right on and they start to translate that into protein. This is the primary level of regulation.

    00:43 Let us look at the structure of a polycistronic gene. Here we have a cluster of genes and those genes are coregulated by one set of promoters and operators. This whole thing together is called an operon. Prokaryotes have operons, all the components that come together to allow gene expression. We have on that operon regulatory region and the regulatory region is what regulates expression and then we will have a coding region. In the regulatory region, we see a promoter and the promoter region is where the RNA polymerase will bind.

    01:30 And then we have an operator region. The operator region is where we could put a repressor protein so that the polymerase cannot make its way down the template DNA and make any mRNA.

    01:46 So, upstream of those, we also have regulatory gene. This is the gene that codes for the regulatory protein that might bind into the operator region. The regulatory proteins have a promoter sequence of their own. We can get one more level complex of how is that one activated, but let us not go there because we will get very confused. We will stay on this track. Upstream regulatory gene has its own promoter and we can transcribe that regulatory gene. But that regulatory gene could either exhibit negative control over gene expression or positive control over gene expression. In negative control mechanisms, we see that this gene codes for repressor proteins that bind onto the operator and stop transcription. And it could be a positive control in which it makes an activator protein that accelerates transcription. We are going to look at some of the negative control mechanisms in a little bit more detail, but downstream of all of these, we have the actual genes in sequence that are going to be transcribed all into one mRNA, which can then be made into multiple different protein types. Let us look at an example. The lac operon


    About the Lecture

    The lecture Prokaryotic Gene Expression by Georgina Cornwall, PhD is from the course Gene Regulation.


    Included Quiz Questions

    1. …the level of transcription.
    2. …the level of DNA replication.
    3. …the level of reverse transcription.
    4. …the level of respiration.
    5. …the level of DNA repair.
    1. An operon is a functioning unit of genomic DNA composed of a cluster of coregulated genes under the control of a single promoter in prokaryotes.
    2. An operon is a structural unit of mitochondrial DNA composed of a cluster of genes under the control of two different promoters in the fungi.
    3. An operon is a structural unit of mitochondrial DNA composed of a cluster of genes under the control of two different promoters in the animals.
    4. An operon is a structural unit of mitochondrial DNA composed of a cluster of genes under the control of two different promoters in the reptiles.
    5. An operon is a structural unit of mitochondrial DNA composed of a cluster of genes under the control of two different promoters in the plants.

    Author of lecture Prokaryotic Gene Expression

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD


    Customer reviews

    (1)
    5,0 of 5 stars
    5 Stars
    5
    4 Stars
    0
    3 Stars
    0
    2 Stars
    0
    1  Star
    0