Darwin
Name Darwin’s mechanism for how species change
Natural selection
What substance did Miescher isolate, and from which cells?
“Nuclein” from white-blood-cell nuclei (pus).
What cell process did Sutton study
Meiosis.
What is “Photo 51,” and when was it taken?
DNA X-ray diffraction image, May 1952.
In what year did they publish the model, and what was it?
1953; DNA double helix.
: What key problem about heredity did Darwin leave unsolved
Identity of the physical carrier of traits.
What chemical clue did “nuclein” show?
High phosphorus content.
What happens to chromosome pairs in meiosis that explains inheritance?
They segregate so gametes get one of each type.
What pattern in Photo 51 indicates DNA’s shape
X-pattern → helix
State the base-pairing rules
A–T and G–C.
What must any heredity molecule be able to do (two ideas)?
Copy reliably + allow some variation
Why did finding a distinctive nuclear substance matter for genetics
It pointed to a candidate material for heredity.
what chromosome behavior was found?
Segregation (and independent assortment).
how big is dna?
0.34 nm per base but points for 6m per cell or to the moon for a full dana set
How does complementary pairing explain accurate copying
Each strand templates the other during replication.
Why did Darwin’s idea push scientists to hunt for a molecule like DNA?
Needed a material information system to pass traits.
What was “nuclein” later called, linking to modern genetics
Nucleic acid → DNA.
Name the theory Sutton argued from his observations
Chromosome theory of inheritance.
Why did Franklin’s measurements matter for model-building
They constrained any valid structure.
Why is DNA’s width roughly uniform along its length
because it s able to coil up neatly
In Darwin’s terms, why must a “gene molecule” allow rare change?
Enables variation for natural selection to act on.
How did Miescher’s result later connect to chromosomes
Chromosomes are rich in DNA—linking DNA to genes
why does this relate to the DNA story?
“genes” are on chromosomes, a structure scientists could test.
What didn’t Photo 51 show directly?
Replication mechanism (structure ≠ process).
If replication is accurate, why do mutations still occur?
Occasional mismatches/damage escape repair.