List the proteins that unwind DNA during in vivo DNA synthesis. How do they function?

Key Concepts

DNA Helicase

DNA helicase is an essential enzyme that unwinds the double-stranded DNA during replication. It breaks the hydrogen bonds between the nucleotide bases, separating the two strands to allow for the synthesis of new DNA. This process is crucial for the replication fork's progression, enabling the DNA polymerase to access the single-stranded templates for new strand synthesis.

Single-Strand Binding Proteins (SSBs)

Single-strand binding proteins bind to the separated DNA strands after unwinding to prevent them from re-annealing or forming secondary structures. By stabilizing the single-stranded DNA, SSBs ensure that the strands remain accessible for the DNA polymerase during replication. Their role is vital for maintaining the integrity of the replication process.

Topoisomerases

Topoisomerases are enzymes that alleviate the torsional strain generated ahead of the replication fork as DNA unwinds. They introduce temporary breaks in the DNA strands, allowing for the relaxation of supercoiling, which facilitates smoother progression of the replication machinery. This function is critical to prevent DNA damage and ensure efficient replication.