1. From Gene to Protein:
Chpt. 17

2. How does the DNA lead to specific traits???
Archibald Garrod (1909) hypothesized: “proteins are the link between genotype & phenotype”

3. Archibald Garrod
Suggested genes control enzymes, & enzymes catalyze chemical processes in cells.
Inherited Diseases are “inborn errors of metabolism” where a person can’t make an enzyme.”

4. Example
Alkaptonuria (Al ka toe nuria)- where urine turns black after exposure to air b/c of chemical alkapton (Al kae ton).
these individuals must lack an enzyme to metabolize (break down) alkapton (the chemical).

5. enzyme
enzyme
enzyme
enzyme

6. George Beadle American(1930)
*“ mutations in eye color (Drosophila) are a result of blocks in pigment production”
*“no enzyme is made - therefore pathway to produce color pigment is not complete… white eyes”
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

8. G. Beadle & Edward Tatum
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
Beadle and Tatum set out to provide experimental proof of the connection between genes and enzymes.

9. Nobel Prize in Physiology or Medicine 1958
G. Beadle & Edward Tatum
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
Cal Tech.
Rockefeller Inst. NY, NY
Nobel Prize in Physiology or Medicine 1958
"for their discovery that genes act by regulating definite chemical events"

10. G. Beadle & Edward Tatum test organism = Neurospora Neurospora
(pink bread mold)
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

11. G. Beadle & Edward Tatum
mutant molds (not wild type) had a variety of special nutritional needs. Unlike their wild type counterparts, they could not live without the addition of particular vitamins or amino acids to their food.
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

12. *“ various mutations must be
G. Beadle & Edward Tatum
*“ various mutations must be
abnormal variations of genes”
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

13. wild type mold survived in minimal medium agar.
One Gene, One Enzyme Hypothesis Beadle & Tatum
this is the normal metabolic pathway
wild type mold survived in minimal medium agar.
The wild type mold can produce all of the enzymes it needs to produce the necessary amino acids to live.
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

14. Mutants did not survive in minimal medium agar.
One Gene, One Enzyme Hypothesis Beadle & Tatum
Mutants did not survive in minimal medium agar.
The mutants must not produce all of the enzymes needed
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
The enzymes would synthesize particular amino acids. But they could survive in complete agar… supplemented with all 20 amino acids.

15. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Experiment
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

16. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Tried to identify where the mutants’ metabolic defects (mutations) were
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

17. One Gene, One Enzyme Hypothesis -Beadle & Tatum
All strains were grown on complete media.
This contained all a.a. & vitamins made by the wild type, they all thrived…
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
By the way, this mold MUST make Arginine in order to grow.

18. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Took mutants out of the complete media
They did not all grow when put on “minimal media”
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
They figured that mutants were unable to produce compounds essential for growth… perhaps their genes did not code for an enzyme… this ultimately did not let the organism produce arginine??

19. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Put each mutant type in different vials containing minimal + one amino acid. (in this pix., the a.a. is ornathine)
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

20. Because Class I grew on minimal medium supplemented with ornithine, citrulline, or argine, it had to be missing enzyme A. This would be required to form all three compounds
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

21. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Class II could not produce citruline, and that is needed for the rest of the pathway to occur... Ornathine “piled up”
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

22. One Gene, One Enzyme Hypothesis -Beadle & Tatum
The media that allowed growth, would show where the metabolic defect (mutation) occurred there was always a “pile up” of the amino acid before
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

23. One Gene, One Enzyme Hypothesis -Beadle & Tatum
If we inactivate one gene, that would code for an enzyme to carry out X -> Y conversion, no product X or Y is produced. If product Y is needed to ultimately produce arginine, no growth will occur
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

24. One Gene, One Enzyme Hypothesis -Beadle & Tatum
The supplement that allowed growth, would show where the metabolic defect (mutation) occurred
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

25. One Gene, One Enzyme Hypothesis -Beadle & Tatum
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

26. One Gene, One Enzyme Hypothesis -Beadle & Tatum
ex. this mutant grew (was able to complete the pathway) in the vial supplemented with Citrulline.
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
therefore, it must be defective in synthesizing Citrulline~ornithine piled up

27. each gene dictates the production of one enzyme
One Gene, One Enzyme Hypothesis Beadle & Tatum
each gene dictates the production of one enzyme
each mutant lacks the ability to produce an enzyme
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

28. One Gene, One Polypeptide Hypothesis -Beadle & Tatum (revisited)
*Some proteins are not enzymes (ex. insulin)
*Some proteins are made of more than one polypeptide chain (hemoglobin)
*Each chain specified by its own gene
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from
One Gene, One Polypeptide Hypothesis -Beadle & Tatum (revisited)

29. How are enzymes (proteins/polypeptides) made?
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

30. How do we get from DNA to protein?
Beadle and Tatum
Found that certain enzymes were missing the enzymes to synthesize particular amino acids
As long as the amino acids were provided for them they could grow but they could not grow on a minimal nutritional medium
These mutants called auxotrophs can grow if all 20 amino acids are provided but the must have increased nourishment which is where their name comes from

31. RNA

32. RNA is the bridge between DNA and Protein
mRNA
The genetic message is read based on triplet coding patterns. The triplet code is read by RNA (codon) and is then translated to another type of RNA (anticodon) which turns the language from nucleic acid to amino acid
tRNA

33. This is the basic process:
TRANSCRIPTION
TRANSLATION
The genetic message is read based on triplet coding patterns. The triplet code is read by RNA (codon) and is then translated to another type of RNA (anticodon) which turns the language from nucleic acid to amino acid

34. No nucleus, protein synthesis occurs same time as transcription.
Transcription occurs in nucleus-> pre -mRNA
Translation occurs on ribos.

35. DNA -->
RNA -->
PROTEIN!

36. Triplets - series of three nucleotides- code for Amino Acids
U not T

37. (1961) Marshall Nirenberg deciphered first codon.

38. (1961) Marshall Nirenberg deciphered first codon.
Won Nobel prize in Physiology and Medicine 1968 for the interpretation of the genetic code and its function in protein synthesis.

40. 1965 Dictionary of Amino Acids
This is the same
for ALL species
of organisms
RNA also reads in the 5’ to 3’ direction . This is an amino acid map which tells the amino acid based upon which nucleotides are transcribed.
There are 64 possible codons 61 of which code for a specific amino acid, the others are stop (2) and Start(1)

41. 1965 Dictionary of Amino Acids
Evolutionary
Significance??
RNA also reads in the 5’ to 3’ direction . This is an amino acid map which tells the amino acid based upon which nucleotides are transcribed.
There are 64 possible codons 61 of which code for a specific amino acid, the others are stop (2) and Start(1)

42. Code Redundancy Third base in a codon shows "wobble”.
First two bases are the most important in reading the code and giving the correct AA. The third base often doesn’t matter.