Why is replication called “semi- conservative”?
A Because each daughter molecule of DNA contains 1 strand from the parent molecule; and one newly synthesized strand
B Because each daughter molecule of DNA contains portions of DNA from the parent molecule interspersed with newly synthesized DNA
C Because during the process a parent molecule is broken down into its constituent nucleotides, which are then used, along with new nucleotides; to make up the daughter molecules:
D Because one daughter molecule is made up entirely of parent nucleotides, the other is made of newly synthesized DNA
The correct answer and explanation is:
The correct answer is: A. Because each daughter molecule of DNA contains 1 strand from the parent molecule; and one newly synthesized strand.
In the process of DNA replication, the term “semi-conservative” refers to the fact that each of the two daughter DNA molecules consists of one old (parent) strand and one newly synthesized strand. This ensures that the genetic information is accurately copied and passed on to the next generation of cells.
The process begins with the separation of the two strands of the parent DNA molecule. Each strand then serves as a template for the synthesis of a new complementary strand. As the DNA helicase unwinds the double helix, an enzyme called DNA polymerase adds nucleotides to the growing strand based on the base pairing rules: adenine pairs with thymine, and cytosine pairs with guanine. This results in the formation of two DNA molecules, each containing one strand from the parent and one strand that is newly synthesized.
The “semi-conservative” nature of replication is significant because it helps ensure that the genetic information is preserved while still allowing for accurate reproduction of the DNA. If the process were conservative (where both strands of the parent molecule stayed intact), or dispersive (where segments of the parent strand and new strand were randomly mixed), errors in replication could occur more easily. The semi-conservative mechanism helps reduce errors, contributing to the fidelity of DNA replication, which is essential for maintaining genetic stability in the organism.
In summary, semi-conservative replication means that the original DNA molecule is “conserved” in each daughter molecule in the form of one parental strand, while the other strand is newly synthesized. This method provides an effective way for cells to ensure that the genetic material is faithfully copied during cell division.