code solution

"Cracking the Code"
What were the Experimental Tools?

Polynucleotide Phosphorylase PNP
was discovered in 1955 by Marianne Grunberg-Manago and Severo Ochoa (Ochoa shared the Noble Prize with Arthur Kornberg in 1959)
Cell Free (in vitro) System for incorporating amino acids into protein.
Measure the Incorporation of Amino Acids (14C-Phenylalanine) into Protein Marshall Nirenberg and J. Heinrich Matthaei in 1966

Artificial mRNA	Radioactivit y (counts.min)
None	44
Poly U	39,800
Poly A	50
Poly C	38

Predicted results and interpretation of a mixed copolymer experiment where a ratio of 1A to 5 C was used.

Possibl e Compo sitions	Concentratio ns	Probability of Occurance of any Triplet	Possible Triplets	Final %
3C	(5/6)(5/6)(5/6 )	128/216=57.9 %	CCC	57.9%
1A:2C	(1/6)(5/6)(5/6 )	25/216=11.6%	ACC CAC CCA	3 (11.6%) = 34.8%
2A:1C	(5/6)(1/6)(1/6 )	5/216 = 2.3%	AAC ACA CAA	3 (2.3%) = 6.9%
3A	(1/6)(1/6)(1/6 )	1/216 = 0.4%	AAA	0.4%

Results of mixed Homopolymer experiment with a ratio of 1 part A : 5 parts C

Amino Acids in Protein	% in Protein	Probable Base Composition and Assignments
Proline	69	CCC, 2C:1A
Histidine	14	2C:1 A, 1C:2A
Threonine	12	2C:1A
Aspargine	2	1C:2A
Glutamine	2	1C:2A
Lysine	1	AAA

Repeating Copolymers - Polynucleotide Phosphorylase would also link di-, tri-, and tetra-nucleotides together to form repeating copolymers

Repeatin g Sequenc e	Polynucleotides	Repeating Triplets
UG	UGUGUGUGUGUGUGUGUGUGUG	UGU GUG
UUG	UUGUUGUUGUUGUUGUUGUUG	UUG UGU GUU
UACG	UACGUACGUACGUACGUACGUACG	UAC GUA CGU ACG

Repeating Copolymer	Codons Produced	Amino Acids in Polypeptide
UG	UGU GUG	Cysteine Valine
AC	ACA CAC	Threonine Histidine
UUC	UUC UCU CUU	Phenylalanine Serine Leucine
AUC	AUC UCA CAU	Isoleucine Serine Histidine
UAC	UAU CAU UCU AUC	Tyrosine Leucine Serine Isoleucine
GAUA	GAU AGA UAG AUA	None

The Triplet Binding Technique

The basic elements of the triplet binding assay are:

E. coli ribosomes + 20 different Aminoacylated tRNAs

Amino Acid Assignments to Specific Trinucleotides derived from the Triplet Binding Assay

Trinucleotide

Amino Acid

UGU, UGC

Cysteine

GAA GAG

Glutamic Acid

AUU AUC AUA

Isoleucine

UUA UUG CUU

Leucine

CUC CUA CUG

Leucine

AAA AAG

Lysine

AUG

Methionine

UUU UUC

Phenylalanine

CCU CCC

Proline

UCU UCC

Serine

UCA UCG

Serine

What is the magic reading device?
Is it a Seer Stone - the Urim and Thummin.

The final result is a simple beautiful table

Evolution of Table

Text iGenetics by Peter J. Russell

This web site is provided for instruction in Botany and Zoology 342

by Kenneth G. Wilson,
Professor of Botany
Miami University
wilsonkg@muohio.edu

Trinucleotide	Amino Acid
UGU, UGC	Cysteine
GAA GAG	Glutamic Acid
AUU AUC AUA	Isoleucine
UUA UUG CUU	Leucine
CUC CUA CUG	Leucine
AAA AAG	Lysine
AUG	Methionine
UUU UUC	Phenylalanine
CCU CCC	Proline
UCU UCC	Serine
UCA UCG	Serine