AP BIOLOGY

Detailed explanation-1: -DNA replicates in the S phase of the cell cycle and initiates at specific regions in the DNA sequence known as DNA replication ‘origins’. A number of proteins participate in DNA replication and the process is subject to scrutiny by cell surveillance mechanisms called cell cycle checkpoints.

Detailed explanation-2: -During S phase, an enzyme called helicase unwinds the DNA strand, in the same way that you would unzip a zipper. The two single DNA strands can then be used as templates to form two identical double DNA strands.

Detailed explanation-3: -S phase is the period of wholesale DNA synthesis during which the cell replicates its genetic content; a normal diploid somatic cell with a 2N complement of DNA at the beginning of S phase acquires a 4N complement of DNA at its end.

Detailed explanation-4: -During every cell division, a cell must duplicate its chromosomal DNA through a process called DNA replication. The duplicated DNA is then segregated into two “daughter” cells that inherit the same genetic information. This process is called chromosome segregation.

Detailed explanation-5: -Abstract. Initiation and completion of DNA replication defines the beginning and ending of S phase of the cell cycle. Successful progression through S phase requires that replication be properly regulated and monitored to ensure that the entire genome is duplicated exactly once, without errors, in a timely fashion.