Transcription Factors: Definition, Types & Roles

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  • 0:01 Transcription Factors
  • 1:02 Transcription and Gene…
  • 2:01 General and Specific…
  • 4:34 Lesson Summary
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Lesson Transcript
Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

How do we go from DNA to a creating a specific cell? It's a complex process, but one that could not function without transcription factors. In this lesson we will discover what exactly transcription factors are, as well as see how they work and help regulate gene expression.

Transcription Factors

Within every cell is a nucleus. Within every nucleus is DNA. And, within that DNA is…you. All of you. Every cell, regardless of what type of cell it is, contains the entire DNA sequence for that individual. So, how do we go from the entire DNA sequence to creating a specific cell? Well, it's…complicated. There's a lot that goes into this, but none of it would be possible without these guys. These are transcription factors, proteins that control the conversion of DNA into RNA. These proteins here are largely responsible for activating the parts of the DNA sequence needed to create a specific cell, so they are pretty important. They can either promote the activation of specific genes or inhibit the activation of others. I guess you could think of them as the lifeguards of the gene pool.

Transcription and Gene Expression

Now, before we get too carried away with our transcription factors here, let's talk briefly about what's going on. As cells replicate, certain genes within the DNA need to be activated in order for that cell to turn into a blood cell or skin cell or whatever it needs to be. For that to happen, the DNA needs to be transcribed, or converted into RNA. The molecule responsible for this transcription is an enzyme called RNA polymerase. So, where do the transcription factors fit into this? Transcription factors are in charge of transcription regulation, which means that they basically tell RNA polymerase where to go. The transcription factors can attract RNA polymerase, promoting the transcription of a gene, or they can block the enzyme, stopping transcription. In short, they control if, when, where, and how efficiently the enzyme RNA polymerase can do its job.

General and Specific Transcription Factors

Now, transcription factors can do all of this by attaching themselves to the enzyme itself, or they can just go straight to the source and attach themselves to the DNA. Where do they do this? It actually depends on what sort of transcription factor we're talking about. Most transcription factors are called general transcription factors. These are the transcription factors that control the beginning of transcription and are sometimes also referred to as basal transcription factors. General transcription factors are very common and are actually required for all RNA transcription. In fact, they are so important to this process that many researchers actually consider them to be a necessary component of life. General transcription factors generally bind to the DNA at promoters, short sections of DNA responsible for initiating the transcription of a particular gene. This is where the entire process kicks off.

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