שאלה | (USMLoid) In mammalian genomic DNA, methylation of C at position 5 of the pyrimidine sometimes occurs in the dinucleotide CpG. These sequences are unusually susceptible to mutation. Which of the following is the reason?

(USMLoid) In mammalian genomic DNA, methylation of C at position 5 of the pyrimidine sometimes occurs in the dinucleotide CpG. These sequences are unusually susceptible to mutation. Which of the following is the reason?

		1. 5mC reduces the strength of hydrogen bonding with its complement on the other DNA strand.
		2. 5mC interferes with progression of the DNA replication fork
		3. Methylated DNA is more frequently subjected to homologous recombination
		4. 5mC may be converted to T by deamination
		5. Methylated DNA is more exposed to exogenous mutagens