Translation AKA, Protein Synthesis Amino Acid Protein tRNA Nucleus mRNA Ribosome (rRNA) Translation AKA, Protein Synthesis

Definition of Translation The process where ribosomes and RNA build proteins following the instructions from DNA RNA  Proteins All three types of RNA must work together for translation to occur

Purpose of Translation (WHY it happens) Translation occurs in order to build the thousands of different proteins needed by the cell to function properly The amino acids that make up proteins must be connected in the correct order to make sure that the protein has the right shape to function properly The genetic code in DNA simply gives the order of the amino acids Look! This answers the question about why AAs need to be in the right order!

When, Where, Who All the time! At the ribosomes (both free in the cytoplasm and attached to the ER) Every living thing!

Steps in Translation (the HOW!) Transcription builds mRNA mRNA joins Ribosome Ribosome reads mRNA Codons tRNA brings Amino Acids to Ribosome tRNA Anti-codons base pair with mRNA codons inside ribosome Ribosome makes Peptide Bonds that join Amino Acids in a chain Processes # 3,4, 5, & 6 Repeat Completed Protein released at Stop Codon

Step 1: Transcription mRNA is made in the nucleus by transcription – only one gene is copied at a time, which gives mRNA the code for one protein (the central dogma)

Step 2: mRNA joins Ribosome mRNA leaves the nucleus through the nuclear pores, and joins a ribosome (it fits between the large and small subunits of the ribosome) (mRNA) (rRNA)

Step 3: Ribosome reads Codons The ribosome “reads” the mRNA message one codon at a time A codon is a group of 3 nucleotides on mRNA that carries the code for one specific amino acid Did you find the codon definition and an example? First codon = AUG Second codon = GCA Third codon = …

Step 4: tRNA brings Amino Acids Each tRNA molecule carries a specific amino acid with it There are 20 different amino acids, and each tRNA can only carry one kind of amino acid The amino acid it has depends on the tRNA anti-codon

More accurate diagrams of transfer RNA….

Step 5: tRNA Anti-codons Base Pair with mRNA Codons tRNA with an anti-codon that matches the mRNA codon joins the ribosome The bases in the mRNA codon must pair with the bases in the tRNA anti-codon to make sure that the amino acids are in the correct order Look! All 3 kinds of RNA working together! Can you write your own anti-codon definition and give an example?

tRNA Anti-Codons pair with mRNA codons inside ribosome

Step 6: Peptide Bonds join AAs The rRNA connects the new amino acid to the other amino acids by a peptide bond This forms a chain of amino acids that grows longer and longer The incomplete chain of amino acids is called a polypeptide – when the entire chain is completed it will be a protein Use this info to compare: 1. amino acids vs.proteins 2. polypeptides vs. peptide bonds

Step 7: Process Repeats The process repeats over and over: The used tRNA leaves the ribosome to get another amino acid The ribosome moves along the mRNA to the next codon Another tRNA brings the next amino acid mRNA codons bond with tRNA anti-codons rRNA forms a peptide bond between AAs And so on….

Step 8: Completed Protein Released Eventually, the ribosome reaches the end of the mRNA The last codon should be a “Stop” codon This signals the ribosome to release both the mRNA and the protein The mRNA can join another ribosome and build another protein The protein goes to do its job!