key term - Meselson-Stahl Experiment

Definition

The Meselson-Stahl experiment is a groundbreaking scientific study conducted in 1958 that demonstrated the semi-conservative nature of DNA replication. By using isotopes of nitrogen, the experiment showed how DNA strands separate and serve as templates for new strands, reinforcing the fundamental principles of molecular biology.

5 Must Know Facts For Your Next Test

1. The experiment utilized two different isotopes of nitrogen: 'N-14' (light) and 'N-15' (heavy) to label the DNA in E. coli bacteria.
2. After several generations of growth in 'N-15', the bacteria were transferred to 'N-14' medium, allowing scientists to observe the density changes in the DNA over time.
3. Results indicated that after one round of replication, the DNA had an intermediate density, confirming that each new DNA molecule contained one old and one new strand.
4. The Meselson-Stahl experiment provided strong evidence against the conservative and dispersive models of DNA replication, solidifying the semi-conservative model as the correct mechanism.
5. This experiment was pivotal in shaping our understanding of molecular genetics and laid the groundwork for future studies in DNA replication and repair.

Review Questions

• How did the Meselson-Stahl experiment differentiate between the three proposed models of DNA replication?
  • The Meselson-Stahl experiment used isotopic labeling to trace DNA replication. By growing E. coli in 'N-15' and then shifting to 'N-14', they could analyze the density of DNA. After one generation, the DNA showed an intermediate density, which supported the semi-conservative model while ruling out conservative and dispersive models because those would have produced distinct patterns not observed in their results.
• Discuss the implications of the Meselson-Stahl experiment on our understanding of molecular biology and genetic inheritance.
  • The implications of the Meselson-Stahl experiment were profound, as it established that DNA replicates in a semi-conservative manner. This finding clarified how genetic information is passed on during cell division, ensuring that each daughter cell receives one original strand from the parent DNA. This process is crucial for maintaining genetic continuity across generations, fundamentally shaping our understanding of heredity and molecular biology.
• Evaluate how the methodologies used in the Meselson-Stahl experiment influenced subsequent research techniques in genetics.
  • The methodologies developed during the Meselson-Stahl experiment laid critical groundwork for future research techniques in genetics. By utilizing isotopic labeling to track molecules, scientists gained powerful tools for studying various biological processes, including transcription and translation. This approach has evolved into modern techniques such as PCR and next-generation sequencing, emphasizing how innovative experimental designs can drive advancements in genetic research and molecular biology.

Related terms

Semi-Conservative Replication: A mode of DNA replication where each new double helix consists of one original strand and one newly synthesized strand.

DNA Polymerase: An enzyme responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand during DNA replication.

Nucleotides: The basic building blocks of DNA and RNA, composed of a sugar, a phosphate group, and a nitrogenous base.