Year: 2022

MENDELIAN INHERITANCE has a number of exceptions that have come to light since Mendel. These include: infectious heredity (L and M viruses, prions); extra nuclear inheritance; genomic imprinting; mosaicism; trinucleotide repeat disorders; gene conversion; epigenetics; CoRR hypothesis for plasmids; Intragenomic conflict and transposons; segregation distortion; homing endonuclease genes; B chromosomes; cytoplasmic genes (anisogamy; feminization; male killing; male sterility); parthenogenesis; cytoplasmic incompatibility; green beard effect. https://lnkd.in/dVC7Cmh View in LinkedIn

"NON-MENDELIAN INHERITANCE is when extranuclear genetic elements are involved or gene conversion alters the allelic proportions." https://lnkd.in/dW8_gaj View in LinkedIn

EXTRANUCLEAR INHERITANCE. "Extranuclear inheritance is a non-Mendelian form of heredity that involves genetic information located in cytoplasmic organelles, such as mitochondria and chloroplasts, rather than on the chromosomes found in the cell nucleus.” https://lnkd.in/dwqn4Df View in LinkedIn

NON-MENDELIAN INHERITANCE. "Both egg and sperm contribute equally to the inheritance of nuclear genes, but extranuclear genes are more likely to be transmitted through the maternal line because the egg is rich in the cytoplasmic organelles where these genes are located, whereas the sperm contributes only its nucleus to the fertilized egg." https://lnkd.in/dwqn4Df View in LinkedIn

TWO DNA SYSTEMS. "The DNA found in chloroplasts and mitochondria is chemically distinct from the DNA in the nucleus." The chloroplast and mitochondria arose from an ancient bacterial engulfment and assimilation. The nucleus was likely once a DNA virus. https://lnkd.in/dwqn4Df View in LinkedIn

DISTINCT SYSTEMS. "The extranuclear genetic systems behave differently from those within the nucleus." https://lnkd.in/dwqn4Df View in LinkedIn

NOT UNIVERSAL. "Even more surprising is the finding that mitochondria have their own, slightly different version of the genetic code, which was previously thought to be common to all organisms, from viruses to humans. In general, because of its greatly smaller size, the DNA found in cytoplasmic organelles has a limited coding capacity." https://lnkd.in/dwqn4Df View in LinkedIn

EXTRANUCLEAR FACTORS. "In addition to the genes found in mitochondria and chloroplasts, extranuclear factors are found in various kinds of endosymbionts (symbiotic organisms that live within the cells of other organisms) and bacterial plasmids." https://lnkd.in/dwqn4Df View in LinkedIn

INDEPENDENT ENDOSYMBIONTS. "Unlike the mitochondria and chloroplasts, some endosymbionts seem to have retained independent genetic systems. The “killer” particles in paramecia, discovered by T.M. Sonneborn in the 1930’s, provide a historically significant example. After many years of controversy, the killer particles were identified as bacterial symbionts." https://lnkd.in/dwqn4Df View in LinkedIn

"MEIOSIS is a specialized type of cell division that reduces the chromosome number by half. This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi. In meiosis, DNA replication is followed by two rounds of cell division to produce four potential daughter cells, each with half the number of chromosomes as the original parent cell." https://lnkd.in/dfR-g7Z View in LinkedIn