CIE A Level Biology復習筆記16.2.7 The Role of Gibberellin in Stem Elongation

Category: A-level課程, 教材筆記, 福利干貨 Date: 2022年8月11日上午11:07

In some plants species their height is partially controlled by their genes
The?Le?gene?dictates the height of some plants
It has two alleles:?Le?and?le
- The dominant allele?Le?produces tall plants?when present
- The recessive allele?le?produces shorter plants?when present (in a?homozygous?individual)
The gene regulates the production of an?enzyme?that is involved in a pathway that forms?active gibberellin?GA1
Active gibberellin is a hormone that helps plants grow by?stimulating cell division and elongation?in the stem
The recessive allele?le?results in?non-functional enzyme
- It is only?one nucleotide different?to the dominant allele
- This causes a single amino acid substitution (threonine -> alanine) in the primary structure of the enzyme
- This change in primary structure occurs at the?active site?of the enzyme, making it non-functional
Without this enzyme?no active gibberellin is formed?and plants are unable to grow tall
Plants that are?homozygous?for the recessive allele?le?are?dwarves
Some farmers apply active gibberellin to shorter plants to stimulate growth