AP BIOLOGY

Detailed explanation-1: -Primase is the enzyme that synthesizes RNA primers, oligonucleotides that are complementarily bound to a nucleic acid polymer. Primase is required because DNA polymerases cannot initiate polymer synthesis on single-stranded DNA templates; they can only elongate from the 3′-hydroxyl of a primer.

Detailed explanation-2: -It is critical that primers are synthesized by primase before DNA replication can occur. This is because the enzymes that synthesize DNA, which are called DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides. Therefore, primase serves to prime and lay a foundation for DNA synthesis.

Detailed explanation-3: -Because the original strands of DNA are antiparallel, and only one continuous new strand can be synthesised at the 3’ end of the leading strand due to the intrinsic 5’-3’ polarity of DNA polymerases, the other strand must grow discontinuously in the opposite direction.

Detailed explanation-4: -DNA polymerase Here are some key features of DNA polymerases: They always need a template. They can only add nucleotides to the 3’ end of a DNA strand. They can’t start making a DNA chain from scratch, but require a pre-existing chain or short stretch of nucleotides called a primer.