How is transcription different in eukaryotic and prokaryotic cells

So we have this yellow part right here, and that's the noncoding region. And it's called the noncoding region because the ribosome is not actually going to read that part.

So that particular sequence of amino acid is not that important. And then after the noncoding region we have the Shine-Dalgarno sequence. And the Shine-Delgarno sequence is the site that the ribosome's going to recognize and bind to.

So let's just throw a ribosome right over here. This is where the prokaryotic ribosome is going to bind. And then after the Shine-Delgarno sequence, we have another noncoding region.

Just gonna abbreviate it NCR. And then we have our start codon, which is typically AUG, so that tells us to start. And so the ribosome's going to start translating, it's going to read this entire section, put together the corresponding polypeptide chain, until it hits the stop codon, which tells it to stop translating.

And then we have another noncoding region. Let's look at our eukaryotic mRNA. And so it's pretty similar, but you can see there are some differences.

So we'll start with our five prime side first. So you see this red nucleotide right over here. That's the five prime cap. And the five prime cap is simply a guanine nucleotide. So I'm gonna draw a G inside, Guanine, and it's going to have a methyl group somewhere on the molecule. So I'm gonna draw a methyl group. And the bond between this guanine and the nucleotide right near it is a bond that's different than the bond that you'd typically find between two nucleotides. And so that's really all the five prime cap is.

And the five prime cap is actually the ribosomal binding site in eukaryotes. So that means that in eukaryotes, the ribosome's going to recognize this particular part and bind to it.

So after the five prime cap, we have this other noncoding region which the ribosome's not going to translate. And then the ribosome is going to hit the start codon again. AUG tells it to start, and it's gonna start translating, so it's going to translate this entire section until it hits the stop codon.

And then we hit something that looks different than what we've seen in the prokaryotic mRNA, so this section with blue nucleotides, and that's called the poly-A tail. And the poly-A tail is a bunch of nucleotides that are all A's, or adenines, so I'm gonna draw A's inside all of these nucleotides.

And the poly-A tail is actually pretty long, so it's typically anywhere between and nucleotides long. So that's pretty long. So I didn't exactly draw it to scale. And the purpose of both the five prime cap, and the poly-A tail is to prevent this mRNA from being degraded by enzymes. So it acts as kind of a signal that does not allow enzymes to break it down or degrade it. Gene Expression Regulates Cell Differentiation.

Genes, Smoking, and Lung Cancer. Negative Transcription Regulation in Prokaryotes. Operons and Prokaryotic Gene Regulation. Regulation of Transcription and Gene Expression in Eukaryotes. The Role of Methylation in Gene Expression. DNA Transcription. Reading the Genetic Code. Simultaneous Gene Transcription and Translation in Bacteria. Chromatin Remodeling and DNase 1 Sensitivity.

Chromatin Remodeling in Eukaryotes. RNA Functions. Citation: Clancy, S. Nature Education 1 1 However, this is where the similarities between prokaryote and eukaryote expression end. Aa Aa Aa. Transcription: An Overview. Transcription in Bacteria. Transcription in Eukaryotes. Figure 1. References and Recommended Reading Hahn, S.

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