Question

knowledge check
quick check
what makes dna replication \semi-conservative\ and ensures genetic continuity?
the original dna molecule remains completely unchanged
both strands in each new dna molecule are completely new
each new dna molecule has one original strand and one new strand
only half of the dna gets copied during replication

Explanation:

To determine the correct answer, we recall the concept of semi - conservative DNA replication. In this process, during DNA replication, the double - helix structure of DNA unwinds, and each of the original (parent) strands serves as a template for the synthesis of a new (daughter) strand. So, each newly formed DNA molecule consists of one strand that was part of the original DNA molecule and one newly synthesized strand.

• The option "The original DNA molecule remains completely unchanged" is incorrect because the original DNA molecule is unwound and used as a template, so it is not completely unchanged.
• The option "Both strands in each new DNA molecule are completely new" is incorrect as this would be the case for a conservative replication model (which is not how DNA replicates), not semi - conservative.
• The option "Only half of the DNA gets copied during replication" is incorrect. In reality, the entire DNA molecule is replicated, with each strand acting as a template.
• The option "Each new DNA molecule has one original strand and one new strand" matches the definition of semi - conservative DNA replication.

Answer:

The option: Each new DNA molecule has one original strand and one new strand