- What did Gregor Mendel call the heritable factors he identified in pea plants, and why did that leave a gap?
- Why did Johannsen choose 'gene' as a neutral term with no assumptions about physical structure?
- What is the difference between genotype and phenotype, and why did that distinction matter for genetics?
Classical Genetics
Mendelian inheritance and the foundational genetics of heredity.
- What was unusual about the white-eyed fly that appeared in Morgan's Drosophila colony in 1910?
- How did the inheritance pattern of the white-eye trait reveal that it was linked to the X chromosome?
- Why was Morgan initially skeptical of the chromosome theory of heredity before this experiment?
- Why did Thomas Hunt Morgan choose Drosophila melanogaster for his inheritance experiments?
- What is chromosomal crossing over and how did it let Morgan map genes to relative positions?
- How did Morgan's fly-room results overturn the idea that genes were abstract 'elements' rather than physical objects?
- Why was Neurospora crassa well suited to Beadle and Tatum's genetics experiments?
- What did Lederberg discover about how bacteria exchange genetic material through conjugation?
- How does bacterial gene swapping via conjugation complicate a strictly Darwinian, gradualist view of evolution?
- How did Barbara McClintock use kernel pigmentation patterns in maize to detect transposons?
- Why did the scientific community largely ignore McClintock's 1951 presentation on jumping genes?
- What later discoveries in bacteria, flies, and humans eventually vindicated McClintock's model of mobile genetic elements?
- How much of the human genome is now estimated to be made up of transposable elements?
- What are transposable elements, and how did Barbara McClintock first notice them in maize kernels?
- Why did the genetics community initially dismiss McClintock's discovery that genes could move within a genome?
- How did the molecular biology revolution of the 1960s and 1970s vindicate McClintock's findings?
- Why did McClintock largely stop publishing her later findings on transposable elements?
- Why are repeated DNA sequences reliable enough to identify a specific individual?
- What work did Tonegawa and Leder share credit for in the 1987 Lasker Award?
- What was the Repository for Germinal Choice and who did it seek donations from?
- What mistake did the Éclaireurs de France scouting group make while cleaning graffiti from a French cave?
- What does this incident suggest about the greatest threats to cultural heritage sites?
- What did Cecil Jacobson allegedly do instead of using anonymous sperm donors at his fertility clinic?
- How was Jacobson's alleged conduct uncovered and how many children was he found to have fathered?
- Why do mutations in signal sequences underlie certain inherited diseases?
- What role do telomeres play in protecting the meaningful parts of a chromosome?
- What are telomeres and why do chromosomes need a protective structure at their ends?
- What is the normal self-recognition advantage, and how was it tested in identical twins?