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What is Transcription?

Transcription Factors

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CancerQuest > Introduction to Cancer Biology > Introduction to Gene Function > What is Transcription? > The Steps of Transcription

The Steps of Transcription

In order for transcription to work, there must be some way of identifying where the process should start and stop. This is accomplished by special proteins, which bind to the start of genes that are to be transcribed. These proteins are called transcription factors.

The process of transcription is divided into several steps:

1. A transcription factor recognizes the start site (promoter) of a gene that is to be transcribed.

2. The enzyme that makes the RNA (RNA polymerase) binds to the transcription factor and recognizes the start region.

3. The enzyme proceeds down the DNA making a copy until the end of the gene is reached.

4. The enzyme falls off and the RNA is released. This copying process may be repeated numerous times.

5. If the RNA is one that codes for a protein, it will leave the nucleus and enter the cytosol.

Remember that the gene depicted above is actually a stretch of nucleotides along a DNA molecule (the chromosome).

The inappropriate activity of transcription factors has been identified in almost all types of cancer known. Since these factors are essential to the orderly activities of a cell, a misbehaving component can have important effects for all of the other parts of the cell. Revisiting the production line analogy, a misbehaving transcription factor might lead to the assembly line being on when it is not supposed to, creating too much product. Alternatively, the line might not be on when it is needed, leading to a deficit of a particular product.