During DNA synthesis, the error rate is on the order of one wrong nucleotide per 1000?

Answer 1

yes, but the polymerase is able to correct most of those errors

Answer 2

Given the complexity of this model, one may wonder why cells don't simply produce an enzyme that synthesizes DNA in the 3' to 5' direction. One possible answer is related to the need for error correction during DNA replication. About one out of every 10,000 nucleotides incorporated during DNA replication is incorrectly base-paired with the template DNA strand. Such mistakes are usually corrected by a proofreading mechanism, which utilizes the same DNA polymerase molecule that catalyzes DNA synthesis. Proofreading is made possible by the fact that the DNA polymerase exhibits a 3'-exonuclease activity, which catalyzes the removal improperly base-paired nucleotides from the 3' end of the polynucleotide chain. This proofreading capability improves the fidelity of DNA replication to the point where an average of only one error occurs for every billion base pairs replicated. If cells did contain an enzyme capable of synthesizing DNA in the 3' to 5' direction, proofreading would not work because a DNA chain growing in the 3' to 5' direction would contain a nucleotide triphosphate at its 5' end. If this 5' nucleotide were an incorrect base that needed to be removed during proofreading, its removal would eliminate the triphosphate group that provides the free energy that allows DNA polymerase to add nucleotides to a growing DNA chain. Hence no further elongation of the DNA chain could take place. - Kleinsmith, LJ. and Kish, VM. Principles of Cell and Molecular Biology, 2nd ed.

Answer 3

It depends upon the type of DNA. Cellular genomic DNA synthesis has a fairly elaborate system of "proof-reading", enzymes that "scan" the newly synthesized DNA and fix mistakes. Proof-reading is very efficient, but not perfect. Therefore, the error rate for copying cellular genomic DNA is about 1 mistake per 10^11 (give or take an order of magnitude; most scientists think the value ranges from about 10^10 - 10^12). However, many DNA viruses (like herpes) have about 1 mistake per 10^7-10^9 replication events.

Incidentally, RNA copying is even "sloppier". Flu virus and HIV virus have an error rate of about 1 per 10,000 - that's why their mutation rates are so high!

Answer 4

>>>Does DNA error checking proves human evolution is wrong?<<< No. What you are estimating is the rate of mutations due to DNA replication. However, there are many other ways that mutations happen such as: recombination, environmental causes (chemical, radiation), viruses, transposons. >>>The fact is that any attempt by the DNA to change is stopped and reversed.<<< This is obviously wrong as that is how cancers begin, with the slow accumulation of mutations. >>>The scientific fact that DNA replication includes a built-in error checking method and a DNA repair process, prove the evolutionary theory is wrong. <<< The scientifically illiterate should not try to use science to argue against evolution because you will fail. Evolution happens. It is defined as change in allele frequency in a population over time. This is measured. This is predictable. You omit a key element in evolution which is generation time. What this argument does show and what the diversity of human genomes shows is that all the different human populations on all the continents could not have descended from a single mating pair of primates that lived only ~10,000 years ago. A primoridal Adam & Eve would have mutated the species out of existence if they had to produce all of the different populations we see now in such a short period of time. However, the diversity of alleles found in humans can easily be accommodated with a species age of ~200,000 years.

Answer 5

1 per 1 billion.

Answer 6

i thought that it was one per billion

Answer 7

What's the question?