Kamis, 01 April 2010

DNA Mutations Between Generations

How often do errors in DNA replication occur between generations – i.e., how many times are new mutations found in a child that were not present in a parent? These new mutations created between generations would represent a “human mutation rate”. Undoubtedly they would contribute to human evolutionary change.

The human mutation rate per generation has been difficult to measure, but several different laboratories have now come up with numbers that are remarkably similar. According to the most recent estimate, the answer is about 60 DNA nucleotide base errors per generation. That sounds like a lot, but given that there are 3 billion nucleotide base pairs (6 billion bases) in the DNA in a human cell, that’s just one error in every 100 million bases. DNA replication and repair mechanisms are remarkably accurate, it seems.

And that’s why human evolution has occurred so slowly, over several million years.

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