Non Mendelian inheritance
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Cytoplasmic or extranuclear inheritance refers to the transmission of traits through genetic material found in organelles outside the nucleus, primarily due to DNA in mitochondria and chloroplasts. This document outlines the history, features, types, and implications of cytoplasmic inheritance, including maternal inheritance, infectious inheritance, and maternal effects on phenotype. Key examples and mechanisms, such as mitochondrial inheritance and the endosymbiotic hypothesis, are also discussed.
Non Mendelian inheritance
- 2. Extranuclear Inheritance Inheritance of traits from parents to off springs from cytoplasmic organelle genetic material is known as extranuclear inheritance or cytoplasmic inheritance. it is mainly responsible due to DNA present in cytoplasmic organelle. total genes present in cytoplasm is know as as plasmon.
- 3. History:- Carl corren in 4 o΄clock plant and baur in pelargnium zonale in 1908. In 1924, jenkins described the iojap leaf variegation in maize. Rhodes in cms in maize in 1933. Sonneborn discovered kappa particles in paramecium. Cp DNA discovered by Ris and Plaut in 1962. Nass and coworker discovered in mt DNA in 1954.
- 4. Features of cytoplasmic inheritance. Reciprocal inheritance. Lack of segregation. Irregular segregation in biparental inheritance. Somatic segregation. Association with organellar DNA. Nuclear transplantation. Mutagenesis Lack of chromosome. Lack of association with A Parasite,symbiont or virus.
- 5. Types of Extranuclear Inheritance 1. Maternal (organelle) inheritance 2. Infectious inheritance 3. Maternal effect on phenotype
- 6. Maternal (organelle) inheritance Eukaryote cells contain mitochondria (plants, fungi, and animals) and chloroplasts (plants only). Both have genomes organized as a single circular chromosome.
- 7. Chloroplasts vary between 120 & 217 kB, according to species • 85kbps in chodia and 2000kbps in acetobularia. • encode ~ 100 proteins, 4 rRNA &~30 tRNA 5 classes of proteins 1. ribosomal & other proteins involved in translation 2. proteins involved in transcription 3. proteins involved in photosynthesis 4. proteins involved in respiration 5. ORFs (open reading frames) sequences capable of encoding proteins but no product has been identified.
- 9. Mito DNA range from 200 to 2500 kb (16 kb for mammalian mito) encodes ~ 35 proteins, also rRNA & tRNA subunits of ATP synthase & complexes I, II, III & IV mtDNA recombines to form new genes, some poison pollen development to create cytoplasmic male sterility Pollen don't transmit mito, May be due to PCD (apoptosis)
- 11. Plastid inheritance. Mirabilis jalapa in 1908.
- 12. Ovule Source Pollen Source White Green Variegated White White Green W, G, var Green White Green W, G, var Variegated White Green W, G, var Leaf Color in Four O’Clocks
- 13. Chlaydomosanas reinhordtii (sager and coworker) • Only one chloroplast is present per cell. Antibiotic resistance comes from mt+ cell. Mitochondria come from mt- cell. • Heteroplasmic cells allow recombination between DNA in the two choloroplasts
- 15. Mitochondrial Depletion Syndrome Mitochondrial Depletion Syndrome is a maternally inherited disease characterized by multiple muscular and neural symptoms, with a wide variety of severity in different individuals. The severity of the condition is dependent on the number of disabled mitochondria present in the egg. An egg with a large number of disabled mitochondria would result in a child with severe abnormalities An egg with only a few disabled mitochondria would result in an individual only mildly affected. Ex:- LHON,Pearson marrow-pancreas syndrome.
- 16. Mitochondrial and chloroplast inheritance and association with nuclear genes IOJAB IN MAIZE.
- 17. Iojab in maize CGMS
- 18. Promiscuous DNA. DNA segment that transfer from one organelle into the other. ex:- A.thaliana 400-2200genes in nucleus is by endosymbionts.
- 19. Features of organelle genome Circular Multiple copies Encode RNA and protein for organelle In case of biparental recombination doesn’t take place Organelle DNA is replicated by nuclear DNA Accumulation of mutation is higher. CpDNA is larger. Recombination is less.
- 20. MATERNAL EFFECT The maternal genome has a strong effect on early developmental events in the newly formed individual after fertilization. Numerous transcripts are synthesized off the maternal genome during oogenesis. These RNA transcripts are not immediately translated; instead, they are preserved in the oocyte.
- 21. The phenotype produced by these archived products is expressed in the zygote (genetically distinct from the mother) but is due entirely to the genotype of the mother.
- 22. Coiling in Limnaea snails Whether the shell coils to the right or left is determined by the maternal genotype and is preserved in the oocyte. Dextral, or right-handed coiling is dominant to sinistral, or left-handed coiling.
- 23. crosses The direction of shell coiling is controlled by the mother’s nuclear genotype The direction of shell coiling in Limnaea is due to a maternal developmental gene which controls the orientation of the spindle in the second mitotic division of the zygote
- 24. The life cycle of the protozoan Paramecium showing steps in conjugation and autogamy.
- 25. Kappa particles of paramecium.
- 26. Genetic Imprinting. Describe a difference in the behaviour of allele of gene contributed by the two parent af an individual. ex:-IGF-II gene encoding in mice.
- 27. Endosymbiotic Hypothesis It is thought that chloroplasts and mitochondria arose from ancient bacteria engulfed by primitive eukaryotic cells. The cells developed a symbiotic relationship that gave the eukaryotic cells the ability to respire aerobically (mitochondria) and capture light energy (chloroplasts).
- 28. Infectious Heredity An invading microorganism may exist in a symbiotic relationship with its host organism. The invader is then passed on in the maternal egg cytoplasm (ooplasm) and confers the beneficial phenotype to the offspring.
- 29. Infectious Heredity in Drosophila The responsible element is a protozoan. When ooplasm from affected individuals or the protozoan itself is injected into oocytes of normal individuals, the temperature- sensitive, altered sex ratio condition results. The condition is due to a sensitivity to a virus, sigma CO2 sensitivity: Affected flies do not recover normally from CO2 anesthesia. They become permanently paralyzed and die. Sex ratio: Affected flies produce predominantly female offspring if reared at 21°C or lower. The condition is transmitted only to daughters, not to the small number of males produced.
- 30. REFRENCES GENETICS,B.D.singh,2nd edition,2009,Kalyani publishers. LIFE SCIENCE, funadmentals and practices-2, Pranav Kumar and Usha mina 5th edition, 2016,path finder publication. www.Slideshare.in