AP BIOLOGY

Detailed explanation-1: -New DNA is made by enzymes called DNA polymerases, which require a template and a primer (starter) and synthesize DNA in the 5’ to 3’ direction. During DNA replication, one new strand (the leading strand) is made as a continuous piece. The other (the lagging strand) is made in small pieces.

Detailed explanation-2: -coli polymerase I has 3′ to 5′ as well as 5′ to 3′ exonuclease activity. The 5′ to 3′ exonuclease operates in the direction of DNA synthesis and helps remove RNA primers from Okazaki fragments.

Detailed explanation-3: -DNA polymerases, the enzymes that synthesize new DNA, can only add nucleotides to a 3′-OH group and therefore extend a DNA strand in the 5′ to 3′ direction.

Detailed explanation-4: -A DNA fragment will be formed in the 5’ to 3’ direction because of the polarity of the DNA molecule. Adding nucleotides to the 3’ end allows DNA polymerase to use the phosphate molecules as “fuel, ” and add a new nucleotide to the DNA strand.