- What is chromosomal crossing over and how did it let Morgan map genes to relative positions?
DNA Repair
Cellular mechanisms that fix damage to genetic material.
- How does moving-boundary electrophoresis separate proteins that look identical in solution?
- How did Chargaff's rules become a clue Watson and Crick used to work out DNA's structure?
- How does the base-pairing rule (adenine with thymine, guanine with cytosine) suggest a mechanism for copying genetic material?
- What did Watson and Crick's double helix model predict about how DNA copies itself?
- How did Meselson and Stahl use heavy nitrogen-15 and density-gradient centrifugation to test DNA replication?
- Why did the appearance of a single intermediate-density band after one generation, then two bands after the second, confirm semiconservative replication?
- What competing models of DNA replication did the Meselson-Stahl result rule out?
- How did Arthur Kornberg demonstrate that DNA could replicate itself in a test tube?
- How does DNA's base-pairing rule let each strand of the double helix act as a template for copying the other?
- How did an enzyme from Thermus aquaticus enable the polymerase chain reaction (PCR)?
- Why did DNA polymerase need to be heat-stable for Kary Mullis's PCR technique to work?
- What was Alec Jeffreys originally studying when he noticed the individually unique banding pattern in his X-ray film?
- Why are repeated DNA sequences reliable enough to identify a specific individual?
- Which real cases were the first to use DNA fingerprinting, and what did they resolve?
- How quickly did DNA fingerprinting move from an accidental lab observation to routine use in criminal trials?
- How does the polymerase chain reaction turn a tiny DNA fragment into a billion copies?
- What role do primers and a heat-stable polymerase play in each PCR cycle?
- What was actually inside Bijan Pakzad's DNA Cologne and DNA Perfume?
- Why had the word 'DNA' become such a powerful marketing tool by the mid-1990s?
- What did Crick and Watson determine about the structure of DNA in 1953, and whose data helped them get there?
- What practical problem did the Southern blot technique solve for molecular biologists?
- What did Alec Jeffreys notice on his 1984 autoradiograph that led to genetic fingerprinting?
- How quickly was genetic fingerprinting first used to solve a criminal case?
- Why do chromosomes lose a little bit of DNA every time a cell divides?
- How many lesions does a human genome sustain in a single day?
- What is the difference between base excision repair and nucleotide excision repair?
- What does mismatch repair actually catch during DNA copying?
- Why do mutations in these repair pathways raise cancer risk?
- What did Evelyn Witkin discover about how bacteria respond to UV-induced DNA damage?
- How does the mammalian DNA damage response network decide between repair, pausing division, or cell death?
- Why does a broken DNA damage response pathway lead to cancer?
- How did researchers confirm that hairy-legged vampire bats had fed on human blood?
- How does a guide RNA let CRISPR-Cas9 find one exact sequence among three billion base pairs?