Mitochondrial DNA Replication

This presentation deals with DNA replication in mamalian mitochondria. Mammalian mtDNA is replicated by proteins distinct from those used for nuclear DNA replication. According to the strand displacement model, replication is initiated from two distinct origins, OH and OL.

1. GARRY D. LASAGA MITOCHONDRIAL DNA REPLICATION 02/03/2018 1 Compiled by: GARRY D. LASAGA

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5. Figure 14-3 Essential Cell Biology (© Garland Science 2010) 02/03/2018 5

6. Figure 3. Transmission electron microscopy images on mitochondria 02/03/2018 6

7. % 20 % 40 % 60 % 80 % 100 % Mitochondrial DNA Nuclear DNA 1 % 02/03/2018 7

8. Mitochondrial DNA mtDNA is double stranded circular DNA molecule mt DNA contain 37 genes for normal mitochondrial function 13 genes make enzymes involved in oxidative phosphorylation 02/03/2018 8

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11. Specific genetic code 02/03/2018 11

12. Maternal Inheritance of mtDNA mtDNA is transmitted through the female egg mtDNA is nonrecombinant During fertilization, the sperm only contributes its nucleus (23 chromosomes) Mitochondria of the sperm cell are located at the mitochondrial sheath which is destroyed upon fertilization (there are some recent studies that oppose this claim) . 02/03/2018 12

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14. The Mitochondrial Genome 16,569 base pairs ( bp ) in length (16-18 kbp ) Encodes for 37 genes, 13 proteins, 22 tRNAs , and 2 rRNAs Two general regions: C oding region Control region 02/03/2018 14

15. The Mitochondrial Genome Mitochondrial DNA is maternally inherited in most species( Gyllesten et al ., 1991) It does not recombine (Hayashi et al ., 1985) Though some evidence of recombination events has recently been reported (Eyre-Walker et al ., 1999; Hagelberg et al ., 1999 ) 02/03/2018 15

16. NUCLEAR DNA MITOCHONDRIAL DNA Found in the nucleus Found in the mitochondria 2 sets of 23 chromosomes Each mitochondria may have several copies of the single mtDNA molecule Maternal and paternal Maternal only Can “ discriminate between individuals of the same maternal lineage” Cannot “ discriminate between individuals of the same maternal lineage” 02/03/2018 16

17. NUCLEAR DNA MITOCHONDRIAL DNA Double helix Circular DNA is packed into chromatin DNA is not packed into chromosome 02/03/2018 17

18. D-loop region F P TAS 1 2 3 LSP HSP OH 02/03/2018 18

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