Question

DNA replication occurs by adding ________.

		1: NTPs to the 3′ end of the daughter strand
		2: dNTPs to the 3′ end of the daughter strand
		3: dNTPs to the 5′ end of the template strand
		4: dNTPs to the 3′ end of the template strand
		5: NTPs to the 5′ end of the daughter strand

Answer 1

DNA replication occurs by adding dNTPs to the 3′ end of the template strand. While dNTPs contain deoxyribose sugar, NTPs have ribose sugar. NTPs are required for RNA synthesis. DNA replication occurs by adding dNTPs to the 3′ end of the template strand because of DNA polymerase. DNA polymerase requires a free hydroxyl group. The free hydroxyl group is available at the 3'end of the template strand. As DNA polymerase requires a free hydroxyl group for adding dNTPs, DNA replication does not occur by adding dNTPs to the 5'end of the template strand. The daughter strand is the strand that is newly formed as a result of DNA replication. Hence, DNA replication does not occur by adding dNTPs to the 3' end of the daughter strand. DNA replication does not occur by adding NTPs to 3' end or 5' end of the daughter strand as NTPs are added to RNAs.