Which spontaneous lesions in DNA occur most frequently in a

Which spontaneous lesions in DNA occur, most frequently in a mammalian cell? ____ uses its RNA component as a template to polymerize DNA sequences at the chromosome ends to solve the \"end-reparation\" problem. What combination of the following events normally prevents the origins of replication in the yeast Saccharomyces cerevisiae from \"firing\" more than once during the cell cycle? Choose two of the following options. The helicase Memel can be delivered to the origin recognition complex (ORC) only in S phase The helicase can only become active (by phosphorylation) in S phase The ORC can only become active (by dephosphorylation) in G_1 phase C The helicase-loading proteins Cdc6 and Cdt1 are only active in S phase

Solution

3. Depurination. This results in formation of apurinic site which in turn results in alteration of the structure of DNA. This is the most common form of spontaneous lesion in DNA.