Complementation test; AC-DS System in Maize

Complementation test; AC-DS System in Maize
transposable elements/Jumping genes
with pictures and explanation.

1. COMPLEMENTATION TEST; AC – DS SYSTEM IN MAIZE COURSE TEACHER: Dr. DHIVYA PRIYA

2. AC –DS SYSTEM Ac / Ds transposable controlling elements was the first transposable element system recognized in maize . The Ac Activator element is autonomous, whereas the Ds Dissociation element requires an Activator element to transpose. Ac was initially discovered as enabling a Ds element to break chromosomes.

3. 4563 base pairs in length and Ds elements are Ac elements that have undergone deletions. Ds elements move only in presence of Ac elements. Mc clintock identified that two controlling elements Ac & Ds and C gene are responsible for genetic instability of corn seed colour (purple, dotted, & yellow).

4. Transposable elements also called as controlling elements, jumping genes, mobile genetic elements or transposons are DNA sequences that move from one location in the genome to another. The process by which these sequences are copied and inserted into new site in the genome is called transposition and the enzyme is known as transposase .

5. If reversion of c to C occurs ( Ds again comes out of C gene insertion site) and cell will produce purple pigment and a spot seeds.

6. TRANSPOSABLE ELEMENT CLASSIFIED BASED ON HOW THEY TRANSPOSE:

7. COMPLEMENTATION TEST Complementation test , also called cis -trans test , in genetics, test for determining whether two mutations associated with a specific phenotype represent two different forms of the same gene (alleles) or are variations of two different genes. The complementation test is relevant for recessive traits (traits normally not present in the phenotype due to masking by a dominant allele).

8. In instances when two parent organisms each carry two mutant genes in a homozygous recessive state, causing the recessive trait to be expressed, the complementation test can determine whether the recessive trait will be expressed in the next generation.