The graph below shows the temperature changes over time during a single cycle of the polymerase chain reaction (PCR):
Which of the following correctly describes the molecular events occurring during Phase II and Phase III?
Phase II: Primers anneal to single-stranded DNA templates via hydrogen bonding. Phase III: Taq DNA polymerase synthesises complementary strands by forming phosphodiester bonds.
Phase II: DNA helicase unwinds the double-stranded DNA template. Phase III: DNA primers form covalent bonds with the template to initiate transcription.
Phase II: Covalent phosphodiester bonds are broken to separate the target gene. Phase III: DNA ligase joins newly formed Okazaki fragments on the lagging strand.
Phase II: Hydrogen bonds between complementary bases are broken. Phase III: Free DNA nucleotides (dNTPs) pair up with the template strands through peptide bonding.
