DNA replication is semiconservative, meaning that each strand in the DNA double helix acts as a template for the synthesis of a new, complementary strand.
During DNA replication, the double-stranded DNA helix unwinds with the help of the enzyme helicase, and the strands are separated. These strands act as templates for the formation of complementary “daughter” strands. After replication, two new double-stranded DNA molecules are formed, each containing one new daughter strand and one old “parental” strand. Thus, the process is semiconservative, as half of the resulting DNA is old and half is new. You can see this depicted in the diagram below:
Practice Questions
Khan Academy
MCAT Official Prep (AAMC)
Practice Exam 1 B/B Section Passage 1 Question 4
Practice Exam 1 B/B Section Question 57
Key Points
• DNA replication is a semiconservative process.
• The two DNA double helix molcules formed after replication contain one old or “parental” strand and one new or “daughter” strand.
Key Terms
DNA replication: The process by which DNA is copied in a cell.
Semiconservative: Describes how newly formed double-stranded DNA molecules after replication contain one old strand and one new strand of DNA.
DNA double helix: DNA molecules in cells consist of two strands of DNA, connected by hydrogen bonding between nucleotide pairs, that twist together into a helical structure.
Complementary: Describes the pattern of pairing between specific nucleotides in DNA and RNA.
Helicase: An enzyme that separates double-stranded DNA into single strands and is important for DNA replication.
Daughter strand: Refers to the newly synthesized strand of DNA during replication.
Parental strand: Refers to the old strand of DNA that is used as a template during replication.
