How the change of one amino acid caused the configuration change in the protein. What would happen if you lost a Stop codon? These are used to terminate translation they indicate the end of the gene’s coding region. Note that three codons are referred to as STOP codons: UAA, UAG, and UGA. The diagram also contains a version of the Genetic Code table, showing the relationship between codon and amino acid. There is an Aminoacyl tRNA Synthetase for each tRNA-Amino Acid combination.īelow is a diagram showing the pairing of codon to anticodon. Note that an ATP is needed to complete the binding. Below is a very basic cartoon of how an amino acid is added to a tRNA. There is a class of enzymes capable of attaching an amino acid to a tRNA: Aminoacyl tRNA Synthetase. Oppisite the anticodon, you will find a binding site for a specific amino acid.Īminoacyl tRNA Synthase – Addition of an Amino Acid to tRNAĪn amino acid can be attached to the free 3′ end of the tRNA. Codon 2 reads ACG, so the anticodon would read UGC. (Question: Would these be antiparallel?). The corresponding tRNA would have an anticodon reading UAC. On one end of the tRNA, you will find an anti-codon. What would happen if the final nucleotide of condon 3 were changed to a C? To an A? How about the second nucleotide in codon 4? Change the U to an A, what happens?Įach codon is a “genetic word,” and refers to a specific amino acid (thus changes to these words can result in changes to final proteins). In this case, one nucleotide is change to a different nucleotide. Insertions and deletions can change reading frames, but point mutations can also occur. For example, if a nucleotide is inserted between codon 2 and 3 (G G), would you have the same reading frame down stream? What if you deleted the first nucleotide of codon 4? What is the effect of changing the reading frame? What would happen to the resulting protein? This is critical! Mutations can affect reading frames. From the start codon, every three sequential nucleotides will be viewed as a codon. The start codon established the Reading Framefor translation. Nearly every organism (and every gene) that has been studied uses the three ribonucleotide sequence AUG to indicate the “START” of protein synthesis (Start Point of Translation).Īs we will see tomorrow, it takes more than a start codon to initiate transcription, but for now, just remember that this is the codon that indicates the START point of the instructions on how to make a protein. This is important! AUG is the Universal Start Codon. In the image to the right, you have sequential nucleotides divided up into codons. So, how do you read this code or nucleotide language? Three sequential nucleotides that represent a genetic (nucleotide) word. But what is the code? The nucleotide language of mRNA can be divided into codons. Translation is the process of “reading” mRNA and using the code to construct a protein.
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