Replication bubbles describe which concept?

• A. They indicate replication happens from multiple origins.
• B. They occur only in prokaryotes.
• C. They are a sign of transcription.
• D. They stop replication.

Answer: (A)

Replication bubbles form where DNA replication has started and bidirectional forks move outward from origins. Their presence shows that replication is initiated at origins and expanding, creating a unwound, newly synthesized region that grows as replication proceeds. In organisms with many origins, you see multiple bubbles corresponding to each origin; prokaryotes usually have a single origin, so you’d typically see one prominent bubble. This concept is about replication, not transcription, and replication bubbles don’t indicate stopping replication—they mark active, ongoing replication from origins.