Watson and Crick Paper (3)

Watson and Crick Paper

Why was watson and crick’s paper significant

discovered 3d shape of DNA

Watson and Crick's paper is significant because it explained how

the genetic material could be so stable, but also how it could

replicate.

Why was it well received?

It was so well received because it fit well known but unexplained

data (e.g. Chargaff ratios, ability of DNA to withstand heat in

Griffith experiment).

Watson and Crick were NOT experimentalists, they generated no

new data.

Why is a triple helix molecule not plausible?

1. it doesn’t make sense chemically for negative phosphate group and for the hydrogen bonds and van der waal’s interaction to hold those 3 together

actual DNA structure

double helix

why did they propose complementary base pairing

• chargaff’s rule, same percentages of a-t, g-c

• specific base pairing always pyrimidine-purine

• explains their hydrogen bonds

why not ribose

one oxygen alone would not be stable enough

Why did Watson and Crick suspect a DNA copying mechanism?

they suspect complementary base paring that makes DNA double helix “a pair of templates”

Watson and Crick proposition for DNA mutation - incorrect

possibly due to tautomeric forms, for example how a base changes shape

tautomeric forms

chemicals moving back and forth between two shapes

two main DNA shapes

• B form

• A form

Where do we get new nucleotides from?

food, they are a small percentage of the chemicals

Was the article experiment based?

no, it was entirely theoretical but later proved to be true, they generated no new data

When was it known DNA was genetic material?

Since Avery’s work (and confirmation by Hershey & Chase)