What are transcription factors?

Transcription factors are proteins that bind to specific DNA sequences to initiate the transcription of genes into mRNA.

mRNA that is produced during transcription then carries the genetic code from DNA to ribosomes, allowing the production of proteins. Transcription factors therefore have a crucial role in gene expression regulation.

When a gene is 'switched off', transcription factors cannot bind to DNA. This prevents the transcription process and so the synthesis of polypeptides.

Hormonal control of transcription in plants

In plants, the hormone gibberellin has a key role in germination by promoting the synthesis of the enzyme amylase.

It does this through the following steps:

1. Gibberellin causes the breakdown of DELLA proteins, which are repressor proteins that normally inhibit the binding of transcription factors to DNA.
2. The degradation of DELLA proteins allows transcription factors to bind to DNA.
3. Transcription factors facilitate the transcription of genes responsible for amylase production.

This process highlights the similarity between plant and animal hormone functions in regulating gene expression through transcription factors.