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Wize University Biology Textbook > Gene Expression & Regulation

Eukaryotic Post-Transcriptional Regulation

Eukaryotic Transcriptional Regulation [Transcription Factors, Enhancers and Repressors]Previous Section
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Post-Transcriptional Regulation

RNA Alternative Splicing

In eukaryotes, after RNA has been transcribed, it must be processed before it is exported to the cytoplasm for translation into protein. One such processing is the removal of segments of RNA through splicing.
  • Normally, introns are removed from RNA and exons remain to be expressed.
  • It turns out that some exons can be removed to yield different proteins from the same RNA transcript. This is called alternative splicing.
  • Therefore, this can be considered another level of gene expression control.



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RNA Stability

RNA processing also includes the addition of a 5' cap and a poly-A tail to increase its stability and prevent it from degradation before it gets to be translated.
  • RNA will inevitably still be degraded. If it degrades very quickly (unstable), little protein can be produced from it.
  • RNA-binding proteins (RBPs) can bind to RNA (specifically, to the untranslated regions (UTRs)) to control stability.
  • MicroRNAs (miRNAs) are short RNAs that can bind to protein-coding RNA to be block translation or tag it for destruction by the RNA-induced silencing complex (RISC).
  • Short interfering RNAs (siRNAs) work similarly to miRNAs.
Photo by Lonugget / CC BY

Practice: Alternative Splicing

Alternative splicing is...

Practice: Post-Transcriptional Regulation Mechanisms

Which of the following is true?

Extra Practice
You are studying two distinct protein isoforms which seem to arise from the same gene. The two isoforms seem to arise due to a single base pair change found on the mRNA transcript that changes the C at position 854 on the mRNA to a U. As a result of this change, isoform 1 contains the codon CAG (Glutamine) and is translated into a full length protein. However, isoform 2 contains the codon UAG (Stop) and is translated into a truncated protein. This change is most likely the result of which of the following?
The CRISPR/Cas9 system and RNA interference by siRNA are both methods used to knockdown proteins. Which of the following is NOT a key difference between the two techniques?
There is a gene that codes for a protein that is differentially expressed in lung and heart tissue. What are some possible ways that this gene is post-transcriptionally regulated?
Which of the following accurately describes why a single SNP could affect the expression of more than one protein in eukaryotes?
Which of the following are neither transcribed nor translated?
TATA box
Enhancer
What is the mechanism by which microRNA affects the production of gene products?
The human body often expresses different proteins or amounts of proteins originating from the same gene in different tissues. Which of the following are possible explanations for this phenomena?
There is a gene that codes for a protein that is differentially expressed in lung and heart tissue. What are some possible ways that this gene is post-transcriptionally regulated?
The CRISPR/Cas9 system and RNA interference by siRNA are both methods used to knockdown proteins. Which of the following is NOT a key difference between the two techniques?
You are studying two distinct protein isoforms which seem to arise from the same gene. The two isoforms seem to arise due to a single base pair change found on the mRNA transcript that changes the C at position 854 on the mRNA to a U. As a result of this change, isoform 1 contains the codon CAG (Glutamine) and is translated into a full length protein. However, isoform 2 contains the codon UAG (Stop) and is translated into a truncated protein. This change is most likely the result of which of the following?
You are studying the mRNA concentration levels of a certain cytokine gene in a cell under different stressful conditions. You notice that when the cell is placed under a chemical stressor, the cytokine protein is present at very high amounts in the cells. Once the stressor is removed, cytokine proteins are almost completely gone. You also observe that in both the stressed and non-stressed conditions, the concentration of the cytokine transcript remains the same. What is the most likely explanation for this observation?
Practice: Eukaryotic Cells
Certain proteins are nearly universal amongst eukaryotic cells. However, when comparing different organisms, the sequences of the genes that encode these proteins can vary quite a bit.
Provide two explanations as to how this may be possible.