Question

how did hershey and chase confirm that dna is the genetic material? they built a model of the dna double helix using x - ray crystallography. they showed bacteria could mutate rapidly in different environments. they discovered heat - killed bacteria can pass traits to harmless bacteria. they labeled protein and dna with radioactive markers and found only dna entered infected cells.

Explanation:

1. Analyze each option:

• The first option: Building a DNA double - helix model using X - ray crystallography was done by Watson and Crick, not Hershey and Chase.
• The second option: Showing bacteria can mutate rapidly in different environments is not related to Hershey and Chase's work on identifying the genetic material.
• The third option: Discovering that heat - killed bacteria can pass traits to harmless bacteria was part of Griffith's experiment, not Hershey and Chase's.
• The fourth option: Hershey and Chase used radioactive isotopes to label protein (with sulfur - 35) and DNA (with phosphorus - 32). They found that when bacteriophages infected bacteria, only the DNA (labeled with radioactive phosphorus) entered the bacterial cells, while the protein (labeled with radioactive sulfur) remained outside. This experiment confirmed that DNA is the genetic material.

Answer:

D. They labeled protein and DNA with radioactive markers and found only DNA entered infected cells.