Protein Synthesis: Translation How is mRNA “translated” into a protein?

TRANSLATION Process when the protein is actually made Occurs at the ribosome in the cytoplasm Uses an anticodon on the tRNA to bring an amino acid to the ribosome

5. mRNA leaves the nucleus and travels to the ribosome in the cytoplasm

DNA’s code is copied to mRNA in codon groups. REMEMBER: DNA’s code is copied to mRNA in codon groups. A CODON is a grouping of three nitrogen bases in mRNA that carry the code for an amino acid. G A C U codon codon

Transfer RNA (tRNA) tRNA Has a clover-leaf shape tRNA carries an amino acid at one end and amino acid U A C an anticodon at the other end. anticodon

ANTICODON The anticodon the complement to the mRNA codon. EX: mRNA codon: AUG tRNA anticodon: UAC The tRNA also picks up the amino acid that corresponds to the mRNA codon U A C Anticodon Codon A C G U

But how do we know which amino acid corresponds to each codon? G U

AMINO ACID CHART This chart is used to find the appropriate amino acid using mRNA codons.   U C A G Phenylalanine Leucine Serine Tyrosine Stop Cysteine Tryptophan Proline Histidine Glutamine Arginine U C A G Isoleucine Methionine Threonine Asparagine Lysine Valine Alanine Aspartic Acid Glutamic Acid Glycine First Base Second Base Third Base What would be the amino acid for the mRNA codon UGG? mRNA codon UGG is the amino acid Tryptophan

TRANSLATION mRNA at the ribosome in the cytoplasm ribosome mRNA G A C U mRNA

TRANSLATION 6. tRNA assists by bringing an amino acid to the ribosome 7. tRNA matches its anticodon with the codon of mRNA to place the amino acid in the correct sequence U A C Methionine G A C U

TRANSLATION Methionine Methionine Isoleucine Isoleucine Leucine G Leucine Isoleucine A U Leucine U G STOP A U Peptide Bond Peptide Bond G A C U TRANSLATION

TRANSLATION Stop Codon A special codon called a STOP CODON marks the end of the gene and protein synthesis. Methionine Leucine Isoleucine STOP G A C U TRANSLATION

Polypeptide Chain - A Protein 8. The amino acids bond with peptide bonds and form a polypeptide chain or protein. amino acid peptide bonds polypeptide = protein

REVIEWING TRANSLATION Protein is made 5. mRNA leaves nucleus, goes to ribosome in cytoplasm 6. tRNA assists by bringing an amino acid to the ribosome 7. tRNA matches its anticodon with the mRNA codon, putting amino acids in the correct sequence 8. amino acids bond, forming a protein click to play animation

TRY THIS! TACACCTGCGCATAG Transcribe and translate this segment of DNA: TACACCTGCGCATAG