GENE20001 Lecture Notes - Lecture 11: Plastid, Zygote, Optic Neuropathy
Document Summary
Mitochondria and chloroplasts and the dna/genes they contain are transmitted from parent to progeny but not according to mendel"s laws. Heteroplasmy: e. g of non-mendelian, uni parental inheritance: chloroplasts, mitochondria (may have variable transmission and variable phenotype) Nuclear genes show nuclear inheritance (i. e. normal inheritance in mitosis and meiosis) (mendelian inheritance) Heteroplasmy: cell has two types of organelle due to a mutation in the organelle genome. In cytoplasmic segregation it is possible to give rise to homoplasmic cells. E. g. there is a mutation in plastid that makes it white. White female x green male produces all white offspring. Green female x white male produces all green offspring. Pollen from a white male plant is made of a nucleus with very little cytoplasm with no chloroplasts, so pollen doesn"t contribute cytoplasm/chloroplasts to the gamete. The egg from the green female contains a large cytoplasm with many green chloroplasts. When the gametes fuse the zygote shows the maternal cytoplasmic phenotype.
