When DNA strands separate, what space forms that expands in both directions?

When DNA strands separate, what space forms that expands in both directions?

• A. Replication fork
• B. Transcription unit
• C. Replication bubble
• D. Helix

Answer: (C)

When DNA strands separate during replication, an expanding region of unpaired DNA forms called a replication bubble. This bubble grows in both directions as helicase unwinds at the origin and the two replication forks move outward from each end, exposing more parental DNA to be copied. The forks sit at the edges of this space, where new DNA synthesis occurs. In contrast, a transcription unit is the stretch of DNA that gets transcribed into RNA, and the helix simply refers to the double-stranded form of DNA. So the expanding space created by strand separation is the replication bubble.

When DNA strands separate during replication, an expanding region of unpaired DNA forms called a replication bubble. This bubble grows in both directions as helicase unwinds at the origin and the two replication forks move outward from each end, exposing more parental DNA to be copied. The forks sit at the edges of this space, where new DNA synthesis occurs. In contrast, a transcription unit is the stretch of DNA that gets transcribed into RNA, and the helix simply refers to the double-stranded form of DNA. So the expanding space created by strand separation is the replication bubble.