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George Beadle and Edward Tatum. “One ought to be able to discover what genes do by making them defective”. What do genes do?. What do genes do?. Their Model Organism:. Neurospora crassa. One Gene–One Enzyme Hypothesis. Neurospora crassa. One Gene–One Enzyme Hypothesis.

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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

Adrian Srb and Norman Horowitz (1944)


One Gene–One Enzyme

One Gene–One Protein 

One Gene–One Polypeptide




3’ G C G T T G G A C 5’

3’ A C G T T G G A C 5’

DNA

5’ U G C A A C C U G 3’

mDNA

5’ C G C A A C C U G 3’

Leu

Asn

Cys

Asn

Leu

Arg

proteins




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 atcatatet 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!



Point Mutation Classification

  • In terms of fitness…

  • Beneficial

  • Neutral

  • Deleterious

  • In terms of the code…

  • Silent

  • Missence (replacement)

  • Nonsense

  • Frameshift


Chromosome Mutation Classification

  • Deletion =

  • Addition / Duplication =

  • Inversion =

  • Translocation =



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!)

From Gene to Protein:Outlining Protein Synthesis


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