[MUSIC] So far, we've been talking about the DNA present in the nucleus. And that is the DNA that contains our genetic information, but it turns out there's actually two kinds of DNA within our cell. because not only is there DNA within the nucleus, there is also DNA in what is called the mitochondria. And the mitochondria are present in the cell, and they're part of the energy system, and they contain their own DNA. And it is different to the nuclear DNA, the nuclear DNA is a long chain. The mitochondrial DNA is circular, it has 16,569 bases organised into 37 genes. It does have non-coding regions and they do exhibit the kind of variation you need to distinguish individuals. The good thing about mitochondrial DNA, what makes it useful is that it has a high copy number per cell. Within a single cell, there is only one copy of your nuclear DNA. But there are multiple copies of your mitochondrial DNA, it is also more robust. The nuclear DNA is more resistant to sample degradation. So if you have a biological sample that's old or has been exposed to harsh treatment, then your more likely to be able to extract and analyse the mitochondrial DNA compared to the nuclear DNA. There is a very important difference between mitochondrial and nuclear DNA, and that is mitochondrial DNA is inherited strictly from the mother, not the father. This means that mitochondrial DNA is not unique to an individual. A child will have the same mitochondrial DNA as his mother and the same as the grandmother. All the way up the maternal line. There's also faster mutation, generation to generation in the mitochondrial DNA, and that's because the proofreading is not so good compared to nuclear DNA. So here's an example of the use of mitochondrial DNA for samples from which it's not possible to get nuclear DNA. And this is the case of the Romanovs, the imperial family of Russia. Now following the Russian Revolution in 1917, the royal the imperial family, the Romanov family, that's Arena, and their children were detained ultimately in the city of a Catherineberg. And in 1918, on the orders of Lenin they were murdered, or executed depending on your point if view. The Bolsheviks attempted to destroy the remains and the bones of the Royal family were eventually buried in the woods and the Bolsheviks hoped that they would be forgotten. But they weren't, and after the fall of the communism and the fall of the Soviet Union, the bones were excavated from where they had been hidden, and the Russian government decided to give the imperial family a proper funeral. But if you going to organize a grand funeral for these human remains, you first have to make sure they really are the remains of the imperial family. It's not some thing where you want to have a mistake, that would be very embarrassing. Well the remains have been burned and buried on all sorts. So of course, it's not feasible to get nuclear DNA. But they were able to obtain mitochondrial DNA because that is more robust. So let's look at the imperial family. The father of the family, Tsar Nicholas II, some of his relatives survive the revolution, they escaped from Russia. Now we can trace back Tsar to his mother and his grandmother, Louise of Hasse-Cassel. So Louise of Hasse-Cassel's daughter was Tsar's mother, Tsar has a sister, the sister had a daughter who had a daughter who had a daughter. So we have an impact maternal line, and all the female members of that line will pass down the mitochondrial DNA, which is the same as a Nicholas's mitochondrial DNA. And one set of bones, those of an adult male, there was a match, showing those were the remains of the Tsar. Technically, you could argue they could be the remains of the Tsar's brother, but what happened to the Tsar's brother was known so he can be eliminated from the investigation. Now what about the other remains? The four daughters of the Tsar and his one son Alexi. Well, they won't have the same mitochondrial DNA as the Tsar. They will have the same mitochondrial DNA as their mother the Tsarina Alexandra. The Tsarina Alexandra had a sister, who had a daughter, who had a son. And that son was Prince Philip, Duke of Edinburgh, husband of the Queen of England. Prince Philip therefore, should have the same mitochondrial DNA as Tsarina Alexandra. So he donated a sample of DNA and sure enough there is a march of the mitochondrial DNA with the mitochondrial DNA of the remains of the woman and the children. So this analysis confirmed that the remains found in that forest near Catherineberg were indeed those of the ill-fated Romanov family. Well, while we're talking about the Romanovs. Soon after the murder, stories went around, that one member of the family, the Grand Duchess Anastasia, one of the daughters, had escaped and survived. And a woman appeared in Berlin in the 1920s claiming to be the Grand Duchess Anastasia. And certainly, she has some physical resemblances to the Grand Duchess, and some members of the imperial family thought she was speaking the truth and others thought she was a hoax. Well, ultimately, this woman emigrated to America, married an American became Anna Anderson and died in the state of Virginia in the United States in 1986. Sometime after, she was subjected to a DNA analysis. Now when she died her body had been cremated, but at some point she had a medical investigation and there had been a biopsy and a tissue taken from that biopsy had been preserved. So it was possible to extract DNA from that biopsy sample and it proved that she was not the Grand Duchess Anastasia, she was actually a Polish lady called Franziska. Even with the DNA evidence, that doesn't stop movie companies making a movie about it.
