Gibberellins & DELLA Proteins
Biology: Cambridge International A Level, topic 16.3.3
Gibberellins & DELLA Proteins
Gibberellins are plant hormones that help regulate seed germination. They exert this control by triggering the breakdown of a class of repressor proteins called DELLA proteins.
Role of gibberellins
- Gibberellins have an important role in triggering seed germination.
- Gibberellins do this by triggering the production of the enzyme amylase.
- Amylase allows seeds to breakdown their starch reserves into glucose. The glucose can then be used to provide energy through respiration.
Gene control
- When a seed absorbs water, it triggers the production of gibberellins.
- Gibberellins then break down DELLA proteins.
- DELLA proteins are repressor proteins that bind to and inhibit a transcription factor that promotes amylase transcription.
- Once gibberellins have triggered the breakdown of DELLA, the transcription factor is liberated.
- The transcription factor can then bind to the promoter region of the amylase gene.
- There is then increased transcription of amylase and then seed germination.
Test yourself on Gibberellins & DELLA Proteins
Where do transcription factors bind?
What triggers the production of gibberellins?
Which of the following happens LATEST in seed germination?