Write four main points of chiasma type hypothesis for occurrence of crossing over.

Ans. Chiasma Type Hypothesis :----

(a) During the prophase I in zygotene of meiosis, the homologous chromosomes pair with each chromosome consisting of two chromatids. It is called synapsis.

(b) During pachytene of prophase I of meiosis 2 non sister chromatids break at homologous sites as well as rejoin afterwards.

(c) The rejoining occurs between non-sister chromatides. It leads to some physical exchanges.

(d) Physical exchange leads to reshuffling the genes. In this way the recombination occurs and recombinants are formed.

इन्हे भी पढ़ें :-- 

Mention any two autosomal genetic disorders with their symptoms.Write short notes on: (1) Down's Syndrome (II) Phenylketonuria (III) Klinefelter's Syndrome.

Web Hindi StudyAugust 09, 2022