Final answer:
During DNA replication, single-strand binding proteins (SSBs) are crucial for keeping the DNA helix open to prevent the single strands from rennealing or forming secondary structures, thus facilitating proper synthesis of new DNA strands. The correct answer is option 1) Otherwise the helix will develop negative supercoiling
Step-by-step explanation:
The question involves understanding the role of single-strand binding proteins (SSBs) during the replication of the DNA double helix. During DNA replication, enzymes called helicases unwind the DNA at the origin of replication, forming replication forks. This process introduces tension into the DNA, potentially leading to supercoiling ahead of the replication fork.
To counter this, topoisomerases operate on the DNA to relieve this tension by making precise cuts and resealing the DNA. However, after the strands are separated, they have a natural propensity to reanneal or form secondary structures that are not conducive to replication. This is where SSBs come into play; they bind to the single-stranded DNA to prevent it from reannealing or base pairing with itself, effectively keeping the DNA helix open to allow for the synthesis of the new DNA strands.
Therefore, the correct answer to why SSBs must keep the DNA helix open during replication is to prevent the single-stranded DNA from rennealing or base pairing with itself, enabling the replication machinery, which includes enzymes like DNA polymerase and primase, to correctly synthesize leading and lagging strands of the DNA. This ensures the replication process is efficient and accurate, making the role of SSBs critical in cellular DNA replication.