Molecular biologyLesson 1 of 1 in the course DNA Structure and Function

Experiments Establishing DNA as Genetic Material

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

This lesson follows early discoveries that helped scientists identify DNA as a molecule carrying hereditary information. It begins with Friedrich Miescher’s isolation of nuclein and then examines Frederick Griffith’s transformation experiments and the work of Avery, MacLeod, and McCarty.

In the 1860s, physician Friedrich Miescher isolated phosphate-rich chemicals from white blood cells, also called leukocytes. Because the material came from the cells’ nuclei, he named it nuclein. The substance would eventually be recognized as DNA.

All flashcards

Nuclein
Friedrich Miescher’s name for phosphate-rich material isolated from cell nuclei, later identified as DNA.
Transformation
A change in a cell caused by uptake of external genetic material.
Hershey–Chase isotope labels
Sulfur-35 tracked phage protein, while phosphorus-32 tracked phage DNA.
Chargaff’s rules
DNA contains equal amounts of adenine and thymine, and of guanine and cytosine.
DNA profiling
Comparing DNA patterns to help assess identity or biological relationships.

Quiz questions

  1. In the Hershey–Chase experiment, which molecules did the radioactive isotopes label?Answer: Sulfur-35 labeled protein; phosphorus-32 labeled DNA.
  2. After centrifugation in the Hershey–Chase experiment, where was the phosphorus-32 label found?Answer: In the bacterial-cell pellet.
  3. Which relationships between DNA bases did Chargaff observe?Answer: A=TA = T and G=CG = C.
  4. How did DNA base composition generally compare among different species?Answer: Overall base proportions varied among species.
  5. How can DNA profiling contribute to a forensic investigation?Answer: It can help compare biological samples and assess identity or relationships.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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