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Question : (a) Bring out the inheritance of chloroplast gene with on example. Chloroplast Inheritance |
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Answer» Solution :Chloroplast Inheritance: (i) DNA is the universal genetic material. Genes located in nuclear chromosomes fllow Mendelian inheritance.But certain traits are governed either by the chloroplast or mitochondrial genes known as extra nuclear inheritance. (ii) It is kind of Non-Mendelian inheritance. Since it INVOLVES cytoplasmic organelles such as chloroplast that act as inheritance vertors, it is also called Cytoplasmic inheritance. (iii) It is based on independent, self replicating extra chromosomal unit called plasmogene located in the chloroplast. (iv) IT is found in 4 O' Clock plant (Mirabilis jalapa). (v) Two types of VARIEGATED leaves namely (i) Dark green LEAVED plants (ii) Pale green leaved plants. (vi) When the pollen of dark green leaved plant (male) is transferred to the stigma of pale green leaved plant (female) and pollen of pale green laeved plant is transferred ot the stigma of dark green leaved plant, the `F_(1)` generation of both the crossed must be identical as per Mendelian inheritance. (vii) But in the reciprocal cross the `F_(1)` plant differs from each other. (viii) In each cross, the `F_(1)` plant reveals the character of the plant which is used as female plant. (ix) This inheritance is not through nuclear gene. It is due to the chloroplast gene found in the ovum of the female plant which contributes the cytoplasm during fertilization since the male gamete contribute only the nucleus but not cytoplasm. Pale Green leaved Plant (male) `underset(F_(1)" Dark Green leaved)underset(DARR)(xx)`Dark Green leaved Plant (Female)`""`DArk Green leaved Plant (Male) `underset(F_(1)" Pale Green leaved)underset(darr)(xx)`Pale Green leaved Plant (Female) |
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