The Aleurone Layer Flashcards
What does the term aleurone mean?
It comes from the Greek word aleuron, which means flour.
When does the aleurone layer develop in relation to the endosperm cells?
The aleurone layer develops at the same time as the endosperm cells.
What is the primary function of the aleurone layer during germination?
It produces most of the enzymes that are not present in the kernel before germination.
Where is the aleurone layer located within the grain structure?
It runs below the hyaline layer and above the endosperm.
How thick is the barley aleurone layer?
It is three cells thick, except over the embryo where it is only one cell thick.
Is the aleurone layer living tissue?
Yes, it is living tissue that respires.
Do the cells of the aleurone layer grow or multiply during germination?
No, they do not grow or multiply during germination.
What enzymes are synthesized in the aleurone layer?
- α-Amylase
- Limit dextrinase
- Endoproteases
What is the role of the aleurone layer in relation to β-amylase?
It helps activate β-amylase, which is located in the endosperm.
What is the inactive form of β-amylase activated by during germination?
It is activated by separating it from an insoluble protein.
What processes are thought to activate β-amylase?
Chemical reduction processes and the action of proteolytic enzymes likely from the aleurone layer.
What is the composition of the aleurone layer in terms of lipids and protein?
- Lipids: 30%
- Protein: 20%
What are some other components of the aleurone layer?
- Phosphate
- Phytic acid
- Pentosan-cellulose
- Minerals
- Sucrose
- B vitamins
What materials make up the cell walls of the aleurone layer?
- Pentosans (66%)
- β-glucans (28%)
What percentage of the dry grain weight do the hyaline layer and the aleurone layer together constitute?
8-15% of the dry grain weight.
What distinguishes the aleurone cells in terms of cytoplasm and nuclei?
Aleurone cells have dense cytoplasm and prominent nuclei.
Do aleurone cells contain starch?
No, they do not contain starch.
What is a source of phosphate and other mineral ions in grains?
The aleurone layer.
What is the role of the aleurone layer during germination?
It is the site of enzyme synthesis that helps in the modification of the endosperm.
