Why is DNA replication considered 'semi-conservative'?

• A. DNA replication occurs only in one direction along the DNA strand.
• B. DNA replication results in two completely new DNA molecules.
• C. Each new DNA molecule consists of one original strand and one new strand.
• D. DNA replication requires the complete unwinding of the DNA helix.

Answer: (C)

Verified step by step guidance

1. Understand the concept of 'semi-conservative' replication: In biology, 'semi-conservative' refers to the mechanism of DNA replication where each of the two resulting DNA molecules retains one of the original strands and includes one newly synthesized strand.
2. Visualize the DNA double helix: DNA is composed of two strands that form a double helix. During replication, these strands separate to serve as templates for the synthesis of new strands.
3. Recognize the role of enzymes: Enzymes like helicase unwind the DNA helix, and DNA polymerase synthesizes the new strands by adding nucleotides complementary to the original template strands.
4. Identify the directionality of replication: DNA polymerase can only add nucleotides in the 5' to 3' direction, which means replication proceeds in one direction along each strand.
5. Conclude with the semi-conservative nature: After replication, each new DNA molecule consists of one original strand and one new strand, preserving half of the parental DNA molecule in each daughter DNA molecule.