Mol Bio Quiz

Gregor Mendel Findings 

Traits are inherited in discrete units (genes). Laws of segregation & independent assortment.

Gregor Mendel Method

Crossed pea plants with different traits, tracked offspring ratios.

Thomas Hunt Morgan Findings

Genes are located on chromosomes; discovered sex-linked traits.

Thomas Hunt Morgan Method

Bred fruit flies, showed eye color inheritance linked to X chromosome.

Frederick Griffith Findings

Transformation principle – genetic info from dead bacteria can change live bacteria.

Frederick Griffith Method

Injected mice with smooth (S, virulent) and rough (R, harmless) bacteria. Heat-killed S + live R still killed mice.

Avery, MacLeod, McCarty Findings

DNA is the transforming principle.

Avery, MacLeod, McCarty Method 

Treated Griffith’s heat-killed S extracts with enzymes (protease, RNase, DNase). Only DNase blocked transformation.

Hershey & Chase Findings

DNA, not protein, is genetic material.

Hershey & Chase Method

Labeled bacteriophages with radioactive P (DNA) and S (protein). Only DNA entered bacteria during infection (blender experiment).

Erwin Chargaff Findings

Base-pairing rules (A=T, G=C). DNA composition differs by species.

Erwin Chargaff Method

Paper chromatography & spectrophotometry to measure bases.

Rosalind Franklin & Maurice Wilkins Findings

DNA is a helix with repeating dimensions (about 2 nm width, bases stacked 0.34 nm apart).

Rosalind Franklin & Maurice Wilkins Method

X-ray diffraction (Franklin’s famous Photo 51).

Watson & Crick Findings

Discovered DNA double helix structure; explained complementary base pairing and replication.

Watson & Crick Method

Built 3D models using Franklin’s data & Chargaff’s rules.

Meselson & Stahl Findings

DNA replicates semiconservatively.

Meselson & Stahl Method 

Grew bacteria in heavy nitrogen (¹⁵N), then switched to light nitrogen (¹⁴N). Used density gradient centrifugation to track DNA bands after replication.