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Mitogenomics
By Tyler Steele
Mitogenomics?
• Mito- mitochondria
• Genomics- genome
• Therefore, study of the mitochondrial genome (mtDNA)
Mitochondria
• “Powerhouse of the Cell”
• Also involved in cell signaling, differentiation, and death
• Bound by two membranes
• Origin: Endosymbiotic Theory
• Most supported theory
• Mitochondria were once individual organisms; taken into another organism via endocytosis
• Dual membrane as evidence
• Chloroplasts obtained in a similar manner
Mitochondrial Genome
• Most multicellular organisms- Circular, closed, dsDNA
• Most unicellular organisms (and Cnidaria)- Linear dsDNA
• In humans:
• 2-10 copies per mitochondrion
100-10,000 copies per
cell
• ~16 kb (compared to P. falciparum- ~6 kb and Silene conica- ~11
Mb)
• Lack introns; only one regulatory site (D-Loop)
• H-strand- guanine-rich; 28 genes
• L-strand- cytosine-rich; 9 genes
• Of total 37- 13 for proteins, 22 for tRNA, 2 for large/small
ribosome subunit
Picture : Emmanuel Douzery
tRNA
• Used in translation of mRNA
• “Cloverleaf” secondary structure
• Important components:
• Anticodon- 3 bp sequence complimentary to
codon on mRNA
• 3’ amino acid- CCA sequence at 3’ end forms
ester bond to an amino acid
• Only one amino acid per tRNA
• mRNA strand is translated into a protein
with tRNA and a ribosome
Why study Mitogenomics?
Identification
• Mitochondrial genes are highly conserved, but vary in location by organism
• Recombination of mtDNA only occurs with copies of itself
• mtDNA remains mostly unchanged from parent to offspring
• mtDNA is passed almost exclusively from mother to offspring (matrilineage)
• It has a high mutation rate, but low amino acid substitution in proteins
• It is also easy to isolate, PCR, and sequence
Identification
Homo sapiens
Phylogenetics
Future of Mitogenomics
Future of Mitogenomics
• Even with next generation sequencing, mtDNA is a good target
• We can sequence and perform phylogenetic analyses on larger sample sizes
• We can look at more detailed sequence information
Sources Cited
• https://upload.wikimedia.org/wikipedia/commons/b/b5/Mitochondrion_mini.svg
• McBride et al. “Mitochondria: More Than Just a Powerhouse”
• Andersson et al. “Origins of mitochondria and hydrogenosomes”
• Nosek et al. “Linear mitochondrial genomes: 30 years down the line”
• Taanman “The mitochondrial genome: structure, transcription, translation and replication”
• https://upload.wikimedia.org/wikipedia/commons/1/15/Map_of_the_human_mitochondrial_genome.svg
• Itoh et al. “Tertiary structure of bacterial selenocysteine tRNA”
• http://hyperphysics.phy-astr.gsu.edu/hbase/organic/translation.html
• http://biochem.co/wp-content/uploads/2008/08/trna_diagram.gif
• DeJong et al. “The mitochondrial genome of Biomphalaria galabrata (Gastrodpoda: Basommatophora), intermediate host of Schistosoma
mansoni”
• Ferris et al. “Evolutionary tree for apes and humans based on cleavage maps of mitochondrial DNA”
• Stone et al. “Mitochondrial DNA analysis of the presumptive remains of Jesse James”
• Gill et al. “Identification of the remains of the Romanov family by DNA analysis”