Finding the Hereditary Molecule

Vocabulary flashcards covering key concepts, experiments, and terms related to locating and identifying the hereditary molecule (DNA) as described in the notes.

Heredity

The passing of traits from one generation to the next.

Transforming factor

The substance that transfers genetic information between organisms; term popularized by Griffith (later identified as DNA).

Griffith's transformation experiment

Showed that nonvirulent bacteria could become virulent after exposure to dead virulent bacteria, implying a transferable genetic material.

Avery–MacLeod–McCarty experiment (1944)

Demonstrated that DNA is the transforming principle responsible for heredity in bacteria.

Hershey–Chase experiment (1952)

Provided evidence that DNA is the genetic material by using bacteriophages labeled with radioactive isotopes to distinguish DNA from protein.

DNA (Deoxyribonucleic acid)

The hereditary molecule in most organisms; stores and transmits genetic information and is replicated.

RNA (Ribonucleic acid)

Nucleic acid involved in protein synthesis and, in some organisms, genetic material; uses ribose and is typically single-stranded.

Protein

Macromolecule made of amino acids; once thought to be the hereditary material due to complexity, but not the carrier according to Hershey–Chase.

Nucleus

Cellular organelle containing chromosomes; site of genetic material in eukaryotes.

Chromosome

DNA–protein complex that carries genes; a unit of heredity located within the nucleus.

Fertilization

Fusion of sperm and egg nuclei to form a zygote, restoring the full chromosome set.

Homunculus (preformation theory)

Early (now obsolete) idea that a tiny human resides in sperm or egg and is reproduced through development.

Mutation rate

Frequency of genetic changes; typically low to maintain stability of hereditary information.

32P (radioactive phosphorus)

Radioisotope used to label DNA in Hershey–Chase experiments to track genetic material.

35S (radioactive sulfur)

Radioisotope used to label protein in Hershey–Chase experiments to track protein coats.