AP BIOLOGY

Detailed explanation-1: -The DNA strand in which DNA synthesis in 5’–>3’ direction proceeds continuously in the same direction as replication fork movement is called leading strand. This makes option A correct.

Detailed explanation-2: -Leading and lagging strands One new strand, the leading strand, runs 5’ to 3’ towards the fork and is made continuously. The other, the lagging strand, runs 5’ to 3’ away from the fork and is made in small pieces called Okazaki fragments.

Detailed explanation-3: -Lagging strand: Chunks of DNA, called Okazaki fragments, are then added to the lagging strand also in the 5’ to 3’ direction. This type of replication is called discontinuous as the Okazaki fragments will need to be joined up later.

Detailed explanation-4: -When replication begins, the two parent DNA strands are separated. One of these is called the leading strand, and it runs in the 3’ to 5’ direction and is replicated continuously because DNA polymerase works antiparallel, building in the 5’ to 3’ direction.

Detailed explanation-5: -Each end of DNA molecule has a number. One end is referred to as 5’ (five prime) and the other end is referred to as 3’ (three prime). The 5’ and 3’ designations refer to the number of carbon atom in a deoxyribose sugar molecule to which a phosphate group bonds.