Which alkaloid is used for arresting mitotic division in metaphase?
Answers
Answer:
Cohlchine
Explanation:
By late prophase, a chromosome may be sufficiently condensed to be seen under microscope as consisting of two chromatin connected at their centromere. The centrosome consist of a pair of centrioles and is the site where microtubules, composed of tubular proteins organize to form the mitotic spindle. Centrioles are made up of microtubules, and during prophase each pair of centrioles is replicated and migrated towards the opposite polar region of the cell. There they establish microtubule organizing centre(MTOC) from which a spindle-shaped network of microtubules (called the spindle) developed. Microtubule extend from a MTOC to the kinetochore,a multiprotein structure attached to the centromeric DNA on each chromosome. Most Plants, fungi and some algae lack centrioles to form spindle, thus centrioles are not required for spindle formation in all organism. During late prophase, nuclear membrane has disappeared and spindle has fully formed. MITOSIS CAN BE ARRESTED AT THIS stage by exposing alkaloid chemical termed colchicine that interferes with assembly of spindle fibre. Such treated cells cannot proceed to metaphase until colchicine is removed. Experimental treatment of cells with colchicine results in inhibition of chromosome separation during mitosis (or meiosis) which causes increase in the chromosome number (or ploidy) of the resulting cell.
The same alkaloid chemical is used to arrest cell division at metaphase by inhibiting spindle formation disassembly, hence the chromosome unable to move towards the pole.