THEORIES TO EXPLAIN FINE STRUCTURE OF CHROMOSOME
(1) Multistranded theory
Steffenson 1959 - each chromosome composed of two chromatids (Half Chromosome) and each chromatid composed of 16 DNA molecules.
(2) Folded fibril theory
Du Praw 1965 - Chromosome consist of single DNA variously folded to form two Chromatids.
(3) Unineme theory
Hans Ris (1967) - Each Chromosome consists of two chromatids and each chromatid have one DNA molecule.
This theory is most acceptable as it is supported by meiosis and crossing over studies.