BIOL-UA 21 Chapter Notes - Chapter 4: Ethyl Methanesulfonate, Metastasis, Chemotherapy
22 Mar 2016
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Spontaneous cleavage of chemical bonds in dna. Environmental agents ie ultraviolet and ionizing radiation. Reaction with genotoxic chemicals that are by-products of normal cellular metabolism or occur in the environment. Mutation = a change in the normal dna sequence, can occur during replication when a dna polymerase inserts the wrong nucleotide as it reads a damaged template. Mutations occur at a low frequency as the result of copying errors introduced by dna polymerases when they replicate an undamaged template. If left uncorrected, cells could accumulate many mutations that they could no longer function properly. Dna in germ cells might incur too many mutations for viable offspring to be formed. Defects in dna repair mechanisms and cancer are closely related. When replace mechanisms are compromised, mutations accumulate in cell"s. Dna if mutations afect genes involved in regulation of cell division, cells begin to divide uncontrollably leading to tumor formation and cancer. Dna polymerases introduce copying errors and also correct them.
