Gene Regulation: Proteins, Prokaryotes & Operons

by Georgina Cornwall, PhD

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    Now that you are clear on the mechanisms of gene expression, let us talk about how it is regulated. By the end of this lecture, you should be able to recognize the most common DNA binding motifs as well as explain how an inducible operon functions and explain how a repressible operon functions. We are addressing prokaryotic gene regulation as well as different binding motifs. Let us begin by looking at DNA structure in brief. We have a double-stranded helical DNA molecule, something we haven't talked about is how the size of this works out. Each turn of the helix is about 3.4 nanometers in length and there are 10 base pairs per turn, which means that each base pair distance is about quite 0.34 nanometers apart. The way that the helix happens in the alpha-helical form is we have a major groove where it is wider spacing between the phosphate, sugar backbones and a minor groove where things are much closer together. Previously it was thought that DNA would have to unwind its helical form in order to allow access of the regulatory proteins and polymerase in such that are involved in gene expression. However, now we recognize that this major groove actually gives fairly good access to the base pairing of the nitrogenous bases. And in this figure you can see the three hydrogen bonds that we see between the G and C nucleotides and when we are in the major groove, it is fairly open and so many of the enzymes involved in DNA transcription can actually access that zipper and open it up. Similarly, when we are more in the major groove above the A and T, you can also see the two bonds and those can be accessed. The major groove provides great access for...

    About the Lecture

    The lecture Gene Regulation: Proteins, Prokaryotes & Operons by Georgina Cornwall, PhD is from the course Genetics. It contains the following chapters:

    • Regulatory Proteins
    • Prokaryotic and Eukaryotic Gene Expression
    • A Closer Look on Prokaryotic Gene Expression
    • Inducible Operons
    • Repressible Operons
    • Other Mechanisms of Prokaryotic Gene Regulation

    Author of lecture Gene Regulation: Proteins, Prokaryotes & Operons

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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