Uniparental inheritance of mitochondrial and chloroplast genes refers to the transmission of these genes from only one parent in most eukaryotes. This process is not uniform and varies across species, involving diverse molecular and cellular mechanisms. Organelle genes often fail to recombine even when inherited from both parents, leading to asexual inheritance. Sexual reproduction is less important for organelle genes than for nuclear genes, as organelle genes are fewer in number. Uniparental inheritance can be lost due to selection for reproductive features like oogamy or to reduce the spread of cytoplasmic parasites and selfish organelle DNA. Chloroplast and mitochondrial genes were first identified in 1909 by Baur and Correns for deviating from Mendelian inheritance. Non-Mendelian inheritance is evident through rapid segregation during vegetative reproduction and uniparental inheritance. Chloroplast genes segregate due to random replication and partitioning during cell division. Uniparental inheritance is complex, with various molecular and cellular mechanisms and hypotheses explaining its evolution. Uniparental inheritance patterns vary, with examples like maternal and biparental inheritance in different species. In maize, crosses between green females and mutant males produce only green progeny, while reciprocal crosses yield only mutant embryos. In geraniums, some offspring inherit chloroplast genes from the female, others from both parents, and some from the male. The inheritance of mitochondrial genes in yeast involves haploid cells with different alleles, leading to heteroplasmic zygotes that segregate into homoplasmic cells after several divisions. Uniparental inheritance mechanisms include prezygotic processes like gamete formation, postzygotic processes like embryo development, and stochastic processes affecting organelle distribution. These mechanisms vary across species and include isogamy, anisogamy, and stochastic partitioning. The inheritance of organelle genes is often asexual, even when biparental, due to the lack of recombination. Evolutionary history shows that uniparental inheritance is common but not universal. Many organisms exhibit uniparental inheritance, with exceptions in some yeasts. The evolution of uniparental inheritance involves frequent reversals and parallel changes, influenced by factors like cytoplasmic parasites and selfish DNA. Evolutionary explanations suggest that uniparental inheritance may be advantageous for reducing the spread of selfish organelle DNA, but this is not universally applicable. Natural selection may be slightly reduced by uniparental inheritance, but the effects are minimal compared to the larger nuclear genome. The efficiency of natural selection is influenced by factors like mutation rates, population size, and recombination. Uniparental inheritance can lead to Muller's ratchet, a phenomenon where harmful mutations accumulate, potentially leading to extinction. However, mechanisms like recombination, environmental changes, and compensating mutations can mitigate this risk. The evolution of uniparental inheritanceUniparental inheritance of mitochondrial and chloroplast genes refers to the transmission of these genes from only one parent in most eukaryotes. This process is not uniform and varies across species, involving diverse molecular and cellular mechanisms. Organelle genes often fail to recombine even when inherited from both parents, leading to asexual inheritance. Sexual reproduction is less important for organelle genes than for nuclear genes, as organelle genes are fewer in number. Uniparental inheritance can be lost due to selection for reproductive features like oogamy or to reduce the spread of cytoplasmic parasites and selfish organelle DNA. Chloroplast and mitochondrial genes were first identified in 1909 by Baur and Correns for deviating from Mendelian inheritance. Non-Mendelian inheritance is evident through rapid segregation during vegetative reproduction and uniparental inheritance. Chloroplast genes segregate due to random replication and partitioning during cell division. Uniparental inheritance is complex, with various molecular and cellular mechanisms and hypotheses explaining its evolution. Uniparental inheritance patterns vary, with examples like maternal and biparental inheritance in different species. In maize, crosses between green females and mutant males produce only green progeny, while reciprocal crosses yield only mutant embryos. In geraniums, some offspring inherit chloroplast genes from the female, others from both parents, and some from the male. The inheritance of mitochondrial genes in yeast involves haploid cells with different alleles, leading to heteroplasmic zygotes that segregate into homoplasmic cells after several divisions. Uniparental inheritance mechanisms include prezygotic processes like gamete formation, postzygotic processes like embryo development, and stochastic processes affecting organelle distribution. These mechanisms vary across species and include isogamy, anisogamy, and stochastic partitioning. The inheritance of organelle genes is often asexual, even when biparental, due to the lack of recombination. Evolutionary history shows that uniparental inheritance is common but not universal. Many organisms exhibit uniparental inheritance, with exceptions in some yeasts. The evolution of uniparental inheritance involves frequent reversals and parallel changes, influenced by factors like cytoplasmic parasites and selfish DNA. Evolutionary explanations suggest that uniparental inheritance may be advantageous for reducing the spread of selfish organelle DNA, but this is not universally applicable. Natural selection may be slightly reduced by uniparental inheritance, but the effects are minimal compared to the larger nuclear genome. The efficiency of natural selection is influenced by factors like mutation rates, population size, and recombination. Uniparental inheritance can lead to Muller's ratchet, a phenomenon where harmful mutations accumulate, potentially leading to extinction. However, mechanisms like recombination, environmental changes, and compensating mutations can mitigate this risk. The evolution of uniparental inheritance