AP BIOLOGY

Detailed explanation-1: -2. Pick the correct pair with respect to primers used in DNA replication. Explanation: Short oligonucleotides of RNA are required by DNA polymerase for the synthesis of both leading and lagging strands of DNA due to the requirement of free 3’ end for DNA synthesis.

Detailed explanation-2: -A primer must be synthesized by an enzyme called primase, which is a type of RNA polymerase, before DNA replication can occur.

Detailed explanation-3: -The reason why RNA primers are often used in DNA replication instead of DNA primers is simply because of the unavailability of specific DNA primers. DNA primers are actually more stable than RNA primers, but oftentimes DNA primers are unavailable to compliment the DNA strand sequence to allow DNA replication to begin.

Detailed explanation-4: -The process involves three steps – initiation, elongation and termination. DNA helicase and single-strand binding proteins are responsible for unwinding and stabilization. The replication process is halted as the leading strand of one replication bubble meets the lagging strand of another replication bubble.

Detailed explanation-5: -Primers are short stretches of DNA that target unique sequences and help identify a unique part of genome-let’s say, a gene. Primers are usually 18 to 25 nucleotides long. They can be synthesized in a special lab, and are used in many different ways.