non mendelian inheritance.ppt
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This document discusses different types of extranuclear or cytoplasmic inheritance including organelle heredity, biparental inheritance, and maternal/cytoplasmic inheritance. It provides examples like mitochondrial DNA being maternally inherited, chloroplast traits in Chlamydomonas showing both uniparental and biparental inheritance patterns, and maternal effects determining offspring traits like shell coiling in snails and shoot color in four o'clock flowers. Cytoplasmic inheritance of bacterial-like kappa particles in Paramecium ciliates that can convert strains to killer types is also described.
non mendelian inheritance.ppt
- 2. Extranuclear Inheritance Commonly defined as transmission through the cytoplasm (or things in the cytoplasm, including organelles) rather than the nucleus Generally only one parent contribute RULES: 1. Ratio typical of Mendelian not found 2. Mitochondrial and chloroplast genes show biparental inheritance. 3. Cytoplasmic inheritance is maternal as zygote receives most of cytoplasm from female parent.
- 3. types of extranuclear inheritance Organelle Heredity - mitochondria and chloroplast have their own genetic material. The offspring get their organelles from the mother through the egg when fertilization is with sperm Biparental inheritance in fruit flies and honey bees; yeast and Saccharomyces Maternal/Cytoplasmic - Genotype of the mother determines the phenotype of the offspring. mRNA or protein from the mother gets stored in the cytoplasm of the egg for the zygote to use. the sperm donates only genetic material (DNA) while the egg donates both genetic material (DNA) and cytoplasm with the accompanying organelles.
- 4. Mitochondria have their own DNA and Ribosomes Mitochondria have some of their own DNA, ribosomes, and can make many of their own proteins. The DNA is circular and lies in the matrix in structures called "nucleoids". Each nucleoid may contain 4-5 copies of the mitochondrial DNA (mtDNA). mitochondrial DNA- organelle heriditary
- 5. Human mtDNA • small, double stranded circular chromosome • 16,569 bp in total . Encodes 13 proteins, 22 tRNAs and 2 rRNAs • no non-coding DNA • no introns • polycistronic replication which is initiated from the D (displacement)- loop region Organisation of the mitochondrial chromosome
- 6. Chloroplast Chlamydomonas Chloroplast Unicellular alga : 2 flagella and single chloroplast (50 copies cpDNA) 2 mating types :mt+ and mt- Mating gives diploid cell that immediately undergoes meiosis to form haploid cells Mendelian ratio – 2:2 (mt+: mt-) Streptomycin or erythromycin resistance: chloroplast trait strS and strR strains (streptomycin resistance)
- 7. strS and strR Crosses Offsring always have str phenotype of mt+ parent
- 8. Offspring of strS and strR Crosses mt+(eryr) x mt-(erys) all resistant (uniparental) Mendelian : 2:2(mt+ : mt-) 50% of offspring mt+ and 50% mt- 5% - encoded by nuclear gene (biparental) Zygote : cytohet 95%- chloroplast (uniparental) Only mt+ parent donates cytoplasm
- 9. Uniparental Inheritance of Streptomycin resistance
- 10. Maternal Effect called uniparental inheritance- The phenotype of the offspring is dependent on the genotype of only one parent (in this case the mother). During fertilization the sperm donates only nuclear DNA to the egg. The egg donates both DNA and cytoplasm. In this cytoplasm are many things including: 1. mRNA which can be translated into protein. This mRNA was transcribed from the DNA from the mother (not DNA from the zygote). 2. Protein that has already been translated. Again, the information to make this protein came from the mother’s DNA.
- 11. Maternal Effect Shoot variegation in four o’clock (Mirabilis jalapa)
- 12. Model for the inheritance of shoot color in the four o’clock Chapter 15 slide 12
- 13. Shell coiling in snails (Limnaea peregra) Snails can have either right-handed or left-handed coils. D = Right-handed coil ; d = left-handed coil Coiling in the offspring is dependent upon the genotype of the mother (NOT dependent on her phenotype) DD and Dd mothers -> Right-handed offspring dd mothers -> Left-handed offspring
- 14. If the mother has the “D” allele then she produces an active gene product that directs the formation of right-handed coils in the offspring, regardless of the offspring’s genotype. If the mother is “dd” then no active gene product is produced and the default, left-handed coils result, even if the offspring has a “D” allele. Interpretation : i. The D allele produces a cytoplasmic product that causes dextral coiling. ii. The d allele does not produce this product, and sinistral coiling is produced by default.
- 15. Fig. 8.9 Maternal Effect: shell coiling in snails Uniparental inheritance DD and Dd mothers right-handed offspring dd mothers left-handed offspring
- 16. Inheritance in Paramecium Kappa bodies are elements within Paramecium that cause them to be killers Killer Paramecium kill other Paramecium in the immediate environment Kappa bodies are inherited through the cytoplasm and not through chromosomes Ciliates contain at least 2 nuclei
- 17. Killer Paramecium Uses a Bacterial Toxin (A) The kappa particles are found in the cytoplasm of the Paramecium. (B) Kappa particles are symbiotic Caedibacter that are found in many strains of Paramecium, yet they have their own DNA and divide like typical bacteria.
- 18. Kappa in Paramecium Certain strains are called killer strains because they release paramecin, a substance toxic to sensitive strains Kappa particles contain DNA and protein and require a nuclear gene (K) Kappa particles are bacteria like
- 19. Kappa in Paramecium During this cytoplasmic exchange, the kappa particles present in the cytoplasm of the killer type enter the non-killer type and convert it into a killer type. Paramecium becomes a killer when it receives kappa particles and it becomes a sensitive when it does not receive kappa particles.