What causes a mutation in an enzyme that changes Tyrosine to Alanine?

[Sarup]

Ok, so we all know that Mitochdiria contains its own DNA, mDNA, which codes for 13 of the approx. 80 needed proteins. We all know, that mutations in the mDNA almost always cause diseases in the central-nervous-system, heart and muscles.

Now, I've been asked the following question: One of theese mDNA mutations causes a fault in an enzyme, where the aminoacid Tyrosin has been changed to Alanin. Now, What kind of mutation could cause the changing of Tyrosin to Alanin in the enzyme?


I'm from denmark, so I'm not sure that I've translated the names of the two aminoacids correctly, but it shouldn't be a problem.

And on a sidenote: why do you often see an encreased level of laktate in the victims of this disease?

*yay - my first but definitely not last post here*

 

[iansmith]

First you should look at a table that show the translation of nucleic acid codon to amino acid. What is the difference between the base pair in the tyrosine and alanine codons? This should give the type of mutation. Give the answer I will confirm if it is right or wrong but you have to show some of thinking.

For the sidenote, What is is the role of mitochondria and if the mitchondrial system does not work what are metabolism pathway that are used instead? This should lead you the answer.

 

[Sarup]

Thanks a lot for the hints.

The first you told me to do i can't do now, because i have to go to school to get the book with the table.

The other thing though, i can i right here. I thought of the solution that you pointed out, but I didn't think the answer was that simple.

The role of the mitochondria is of course to provide energy to the body. They do this via a process called respiration. Normally we do this by turning oxygen and glucosis into water, ATP and CO2, but if the mitochondrial system doesn't work, then the body finds another way out:lactate fermentation(at least i think that's the english word for it). This process does not produce a lot of energy, but it does so very fast. When the mitochondrial system fails, lactate fermentation takes over and produces energy (2 ATP) and the bi-product lactate. Hence the higher levels of lactic acid (or lactate) in the sick persons, than in the healthy ones.

I'll return with the first question tomorrow.