## MtDna Degradation

Given the high ROS environment of the interior of the mitochondrion, it is no surprise that the lifetime of mtDNA is relatively short. A typical measurement of the half-life of mtDNA in mammals is approximately 10 days, with some reported values as high as 30 days. It is possible that this measured degradation actually reflects the degradation of the entire organelle. As is generally the case in simulations involving molecular degradation, we model this as a random process. Given a half-life of Thaf, the probability that a given mtDNA molecule will degrade within a time At is

With a population of N mtDNA molecules in a cell, the number of degradation events, nd, that would occur within a time span of At is given by a cumulative Poisson distribution.

The quantity N x Pd is the mean number of degradation events expected, and the Poisson function returns a number that has random fluctuations about this mean. When At ^ Thalf, the mean number of degradation events (nd) is given by

For details on the cumulative Poisson distribution and the binomial distribution used in the next section, I highly recommend the series of Numerical Recipes books (Press et al., 1988), and refer you to the books for details on programming these functions. As a concrete example of the degradation rate, for a population of 10,000 mtDNA molecules with a half-life of 10 days, over a time At of one hour, the mean number of mtDNA molecules degraded would be 29. The actual number returned from the Poisson routine would fluctuate about that mean value.

## Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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