A Mitochondrion that produces energy by converting ADP to ATP.
Mitochondria have their own unique DNA separate from maternal DNA which is subject to mutations that disrupt the correct functioning and production of ATP.
The procedure, which involves genetic material from 2 women and a male, aims to replace the faulty mitochondrial DNA, which can cause muscle weakness, blindness and heart failure. The DNA from the mother and the father are put into another woman's egg which contains healthy, unmutated mitochondria. This fertilized egg is the implanted into the uterus as normal.
Dr Geoff Watts, who led the inquiry, said: "They could offer significant health and social benefits to individuals and families, who could potentially live their lives free from what can be very severe and debilitating disorders."
The Bioethics Council points out that just 0.1 per cent of the child's DNA would come from the donor. The impact on the characteristics of the resulting child from the donor would be so small it can be regarded as negligible, so it would be legally and biologically inaccurate to refer to such a donor as a "third parent".
Some critics that oppose the procedure state that it is akin to Frankenstein's monster being built out of parts from many different bodies and that it violates the norms of nature. Some believe that if this procedure is cleared for use in clinics it will create a slippery slope of unnecessary genetic modification and will lead to the fruition of "designer babies".
Another concern is that the outcomes of the procedure will last more than one generation and will be present in the modified child's offspring.