Biochemistry 2280A Lecture Notes - Lecture 20: Pseudouridine, Chloramphenicol, Phenylalanine
Document Summary
12:42 am mrna is used to synthesize protein. spells out the amino acid sequence in letter words called codons. Cells need at least 20 different codons to code for 20 amino acids. Given that there are 4 nucleotides (a,g,c,u), 64 3 base codons are possible (43) 2 base codon results in 16 codons which isn"t enough for 20 amino acids. 4 base codon results in 256 codons, too excessive. There are 61 codons for 20 amino acids, it"s redundant. Amino acids can be coded by more than 1 codon. The genetic code is universal, found in all organisms. Overlapping would place significant restrictions on what amino acid can come before and after it as they would rely on each other. There are no gaps between codons, gaps were removed by splicing introns. Redundancy: some codons code for the same amino acids. Redundancy often occurs at the third position of the codon(wobble)