Introduction to Regulation of Gene Expression - Online Tutor, Practice Problems & Exam Prep

Gene expression regulation occurs in both prokaryotic and eukaryotic cells, involving a two-step process: transcription (DNA to RNA) and translation (RNA to protein). Regulation can happen at five stages: chromatin rearrangements, transcriptional control, post-transcriptional control, translational control, and post-translational control. Additionally, gene regulation can be positive, stimulating expression, or negative, inhibiting it, akin to a light switch. Understanding these mechanisms is crucial for grasping how cells control protein production and respond to environmental changes.

Introduction to Regulation of Gene Expression

In this video, we're going to begin our introduction to the regulation of gene expression. It's important to know that both prokaryotic and eukaryotic cells have the ability to regulate or control their gene expression. Recall from our previous lesson videos that gene expression is just referring to the ability to express a gene or to create the final product that's associated with a gene. In many cases, the final product of a gene is going to be a protein. If we take a quick look at our image down below, notice we're showing you an image that's showing some gene expression because gene expression typically requires a two-step process. The first step is transcription, which converts or uses DNA to build RNA. Then, the second step of gene expression is translation, which uses the RNA to build a protein. Gene expression, using the DNA to build proteins, has many different stages of regulation, and gene expression can be controlled or regulated at any of five stages. Notice that we have these five stages of regulation or control numbered down below, and these numbers correspond with the numbers that you see in our image. The very first stage of gene expression is going to be chromatin rearrangements, referring to the regulation of chromatin confirmations and controlling DNA's accessibility for transcription. We'll talk more about chromatin rearrangements later in our course. The second stage of regulation of gene expression is transcriptional control. As this sounds, it is going to be controlling or regulating transcription, regulating RNA polymerases binding to the promoter and the initiation of transcription. Most prokaryotic gene regulation actually occurs at this transcriptional control level or stage. We'll be able to talk more about transcriptional control as we move forward in our course. The third stage of gene expression regulation is going to be post-transcriptional control, and "post" is a root that means after. Post-transcriptional control is going to be the regulation of modifications to the RNA after transcription has already occurred. The fourth stage of regulation is translational control, which is, of course, going to be regulating the initiation and elongation steps of translation. The fifth and final stage of gene expression regulation is post-translational control. "Post" again means after, and so post-translational control is going to come after translation. It regulates modifications to proteins after translation has occurred. We'll get to talk more about each of these stages of gene expression regulation as we move forward in our course. But if we take a look at our image down below, what you can see is we're showing you an image of the 5 stages of gene expression and regulation of gene expression. At the first stage, what we have here is chromatin rearrangement, which is going to affect the arrangement of the DNA and the DNA's accessibility to transcription. Then we have transcriptional control, which is going to be the primary way that prokaryotes regulate their gene expression. Transcriptional control is going to again affect the RNA polymerase binding to the promoter and affect the initiation of transcription. Then we have post-transcriptional control, which is going to be modifications to the RNA after transcription has already occurred. Then we have translational control, which is going to affect the initiation and elongation steps of translation. Last but not least, we have post-translational control, which is going to be modifying the protein and affecting the regulation as we move forward in our course. It is important to know that prokaryotes like bacteria and archaea tend to use transcriptional control as their primary way of regulating their gene expression. However, when it comes to eukaryotes, it's important to know that eukaryotic gene regulation can actually occur at any of these five stages. Moving forward in our course, we're going to talk more and more about gene regulation, starting by talking about transcriptional control at the prokaryotic level. Later in our course, we'll double back and talk more about each of these other stages of regulation. For now, this concludes gene expression as we move forward. I'll see you all in our next video.

Positive vs Negative Gene Regulation

In this video, we're going to talk about positive versus negative gene regulation. Cells can regulate their gene expression in one of two different ways. The first way is via positive gene regulation and the second way is via negative gene regulation. Now, positive gene regulation is going to stimulate gene expression by turning on the gene so that the gene's final product is actually being made at a higher rate. Negative gene regulation, on the other hand, is the opposite because it prevents gene expression by turning off the gene so that the gene's final product is being made at a lower rate.

It turns out that positive and negative gene regulation can actually resemble a light switch in a way. Just like light switches can be turned on to turn on the light and can be turned off to turn off a light, genes can also be turned on and turned off via positive and negative regulation. Over here on the left-hand side of our image, notice that we're showing you a light switch being turned on into the on position. This is going to resemble positive gene regulation, the stimulation of gene expression by turning the gene on. Notice over here on the right-hand side of our image, we're showing you the light switch being turned into the off position. This is going to resemble negative gene regulation since negative gene regulation prevents gene expression by turning off the gene.

As we move forward in our course, we're going to see more specific examples of both positive and negative regulation as well. But for now, this here concludes our brief introduction to positive and negative gene regulation, and we'll be able to get some practice applying the concepts that we've learned as we move forward in our course. So, I'll see you all in our next video.

Post-translational control refers to:

• A. Regulation of gene expression after transcription.
• B. Regulation of gene expression after translation.
• C. Control of epigenetic activation.
• D. Period between transcription and translation.

Which of the following is an example of positive regulation of gene expression?

• A. Transcription is halted on a specific gene to limit the amount of protein being created by the gene's expression.
• B. The protein that is translated is immediately degraded by the cell before it can serve its function.
• C. Elongation of translation comes to a stop and the ribosome dissociates when a regulatory protein binds.
• D. A protein binds to DNA and then stimulates the initiation of transcription of a specific gene.

In prokaryotes, control of gene expression usually occurs at the

• A. Splicing of pre-mRNA into mature mRNA.
• B. Post-translational control level.
• C. Transcriptional control level.
• D. All of the above.

Here’s what students ask on this topic:

What are the stages of gene expression regulation in eukaryotic cells?

Gene expression regulation in eukaryotic cells occurs at five stages: chromatin rearrangements, transcriptional control, post-transcriptional control, translational control, and post-translational control. Chromatin rearrangements involve modifying the structure of chromatin to control DNA accessibility for transcription. Transcriptional control regulates the binding of RNA polymerase to the promoter and the initiation of transcription. Post-transcriptional control involves modifications to RNA after transcription, such as splicing and editing. Translational control regulates the initiation and elongation steps of translation. Finally, post-translational control involves modifications to proteins after translation, such as phosphorylation or ubiquitination, affecting their function and stability.

How do prokaryotic and eukaryotic cells differ in gene expression regulation?

Prokaryotic and eukaryotic cells differ significantly in gene expression regulation. In prokaryotes, gene regulation primarily occurs at the transcriptional level, where the binding of RNA polymerase to the promoter is controlled. This is because prokaryotic cells lack a nucleus, and transcription and translation occur simultaneously. In contrast, eukaryotic cells have multiple levels of regulation, including chromatin rearrangements, transcriptional control, post-transcriptional control, translational control, and post-translational control. Eukaryotic cells have a nucleus, so transcription and translation are separated, allowing for more complex regulation mechanisms at each stage.

What is the difference between positive and negative gene regulation?

Positive gene regulation stimulates gene expression by turning on the gene, leading to an increased production of the gene's final product. This is akin to turning on a light switch. Negative gene regulation, on the other hand, inhibits gene expression by turning off the gene, resulting in a decreased production of the gene's final product. This is similar to turning off a light switch. Both mechanisms allow cells to control the production of proteins in response to environmental changes and cellular needs.

What is transcriptional control in gene expression regulation?

Transcriptional control is a stage of gene expression regulation that involves controlling the initiation of transcription. This includes regulating the binding of RNA polymerase to the promoter region of a gene. In prokaryotes, transcriptional control is the primary method of gene regulation. In eukaryotes, it is one of several stages of regulation. Factors such as transcription factors, enhancers, and repressors can influence transcriptional control, determining whether a gene is transcribed into RNA and subsequently translated into a protein.

What are post-transcriptional modifications in gene expression regulation?

Post-transcriptional modifications are changes made to RNA after transcription has occurred. These modifications can include splicing, where introns are removed and exons are joined together; 5' capping, where a modified guanine nucleotide is added to the 5' end of the RNA; and polyadenylation, where a tail of adenine nucleotides is added to the 3' end. These modifications are crucial for the stability, export, and translation of the RNA, and they play a significant role in regulating gene expression.