Mitochondrial genome (mt DNA)

• Relatively small, double stranded circular DNA located in matrix

• Size varies between species

• Human mt DNA 16 Kb (16569 bp)

• Plant cell mt DNA 200 kb-2500kb

• Typically 2-10 copies of DNA in each mitochondria

• Animal mt genome codes for 37 proteins, 2 rRNA genes and 22 tRNA genes, more than 95% of mt proteins are coded by nuclear DNA.

• Genomes are typically AT rich ( 70% approx) and lack introns.

• 70 S ribosomes (mitoribosomes)

• AUA codes for methionine (not Isoleucine)  and UGA codes for tryptophan (not a termination codon as in mammalian genome).

• High mutation rate as DNA repair mechanism is absent.

• Kinetoplast: In trypanosomes, each mitochondria contains 1000 of copies of mt DNA arranged into a complex interlinked structure  called Kinetoplast.

• Division by fission when cell divides.