The Mitochondrial Genome

What does the genome of human mitochondria look like?

It contains 16,569 base pairs of DNA organized in a closed circle.

These encode:

• 2 ribosomal RNA (rRNA) molecules
• 22 transfer RNA (tRNA) molecules (shown in the figure as yellow bars; two of them labeled)
• 13 polypeptides.

The 13 polypeptides participate in building several protein complexes embedded in the inner mitochondrial membrane.

• 7 subunits that make up the mitochondrial NADH dehydrogenase
• 3 subunits of cytochrome c oxidase
• 2 subunits of ATP synthase cytochrome b

All these gene products are used within the mitochondrion, but the mitochondrion also needs proteins encoded by nuclear genes. These proteins are synthesized in the cytosol and then imported into the mitochondrion.