What do genes do George Beadle and Edward

What do genes do? George Beadle and Edward Tatum “One ought to be able to discover what genes do by making them defective”

What do genes do?

Their Model Organism: Neurospora crassa

One Gene–One Enzyme Hypothesis Neurospora crassa

One Gene–One Enzyme Hypothesis Adrian Srb and Norman Horowitz (1944)

One Gene–One Enzyme One Gene–One Protein One Gene–One Polypeptide

A Problem:

The Central Dogma of Biology:

DNA 3’ G C G T T G G A C 5’ 3’ A C G T T G G A C 5’ m. DNA 5’ C G C A A C C U G 3’ 5’ U G C A A C C U G 3’ proteins Arg Asn Leu Cys Asn Leu

The Central Dogma of Biology:

Exceptions to the Central Dogma: 1. 2.

Cracking the Genetic Code = 20 amino acids? George Gamow’s Hypothesis

Cracking the Genetic Code • Analyzed the reading frame by making additions / deletions: Normal: “The fat cat ate the rat” 1 deletion: “The atc ata tet her at” 2 deletions: “The tca tat eth era t” 3 deletions: “fat cat ate the rat” Francis Crick and Sydney Brennar

Triplet Code! • Redundant • Unambiguous • Nearly universal • Conservative

Some Quick Decoding Practice… Who Murdered T. M. R. ? Use decoder on page _____ in textbook!

When the code goes awry. . • Mutation =

Point Mutation Classification In terms of fitness… 1. Beneficial 2. Neutral In terms of the code… 1. Silent 2. Missence (replacement) 3. Nonsense 3. Deleterious 4. Frameshift

Chromosome Mutation Classification 1. Deletion = 2. Addition / Duplication = 3. Inversion = 4. Translocation =

Chromosome Mutation Classification

Protein Synthesis: 2 Stages Stage 1: Stage 2:

From Gene to Protein: Outlining Protein Synthesis • • • Every group member should contribute equally (indicate where) Every term should have an entry / explanation Include images / links to videos whenever possible / helpful You are not expected to cite sources. Share the completed document with Ms. Hines by Wednesday at midnight at the latest (hopefully you can finish today!)