BIOB10Y3 Lecture Notes - Marshall Warren Nirenberg, Sickle-Cell Disease, Phenylalanine
Document Summary
How is the info in nucleic acids (dna, then mrna) converted into the order of amino acids incorporated to build a protein: genetic code. Discovered that 3 nucleotides likely specified the code" for a single amino acid these nucleotides or codons are non-overlapping. Examining the outcome of diseases such as sickle cell anemia (single base substitution) revealed that the code is non-overlapping. Only affected one amino acid = one codon the genetic code is degenerate. 64 possible codons encode 20 amino acids and stop". More than one codon per type of amino acid. Incubated this with bacterial extract (contains all amino acids and factors necessary for protein synthesis) Marshall nirenberg and colleagues synthesized an mrna in vitro solely made up of u"s poly(u) Examined the new polypeptide synthesized it was polyphenylalanine. By similar methods, the coding specificities of each of the 64 codons was discovered.