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Protein Synthesis. The process that turns a unique gene sequence into a specific protein. T. T. A. U. U. U. U. U. U. G. G. C. G. G. T. T. A. C. C. RNA. G. C. C. A. A. T. A. A. A. A. T. A. A. T. T. Protein. A. C. C. G. C. C. C. C. G. C. C. G. G. C.
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Protein Synthesis The process that turns a unique gene sequence into a specific protein
T T A U U U U U U G G C G G T T A C C RNA G C C A A T A A A A T A A T T Protein A C C G C C C C G C C G G C G G The Central Dogma of Genetics:DNA to RNA to Protein Protein Synthesis has two steps: Transcription and Translation
Three Essential Types of RNA • mRNA (messenger): copies instructions in DNA and carries these to the ribosomes in the cytoplasm • tRNA (transfer): carries amino acids to the ribosome and mRNA • rRNA (ribosomal): composes the ribosome
Transcription:DNA is copied into a complementary strand of mRNA *Think of scribes…the people hired to write copies. *Think of transcript…a copy of your grades. • Why go to the trouble of Transcription? • DNA cannot leave the nucleus, and proteins are made in the cytoplasm. • mRNA serves as a “messenger” and carries the protein building instructions to the ribosomes in the cytoplasm.
T T A U U U U U U G G C G G T T A C C RNA G C C A A T A A A A T A A T T A C C G C C C C G C C G G C G G Transcription:DNA is copied into a complementary strand of mRNA Chemical signal “turns on” a gene, and DNA unwinds with the help of an enzyme RNA polymerase pairs RNA nucleotides with their complementary base on one strand. The other strand “hangs out” mRNA peels away, leaves the nucleus, and travels to the cytoplasm
Translation Vocabulary • Translation happens based on a “genetic code” • It is universal to all organisms • Works like a “language” translator taking RNA nucleotides into protein amino acids • Codons are three nucleotides on mRNA • One codon specifies one amino acid • Some are redundant (and code for the same amino acid) *FYI--In 1968 Nirenberg & Khorana jointly were awarded the Nobel Prize for the elucidation of the Genetic Code.
U U U Cys G C A A A A C C C G Translation Vocabulary Aminoacid --there are twenty unique tRNAs to carry each unique amino acid Codon: a set of three nucleotides on the mRNA Anticodon: “complementary” three nucleotides on tRNA tRNA (Transfer) mRNA (Messenger)
U U U U U Cys Cys Cys G G G G C Gln A A A A A Ser C C C G Gln Translation:Interpreting RNA message into protein 1. mRNA attaches to a ribosome (rRNA) 2. First matching tRNA binds to the mRNA start codon (AUG) 3. Next matching tRNA binds 4. A peptide bond is formed between the two amino acids 5. The “empty” tRNA falls off the mRNA 6. New tRNAs move in--each bringing their specific amino acids--continue the growing protein, and the empty tRNA falls off. Continues until a stop codon.
Translation Summary • For each mRNA codon, there is a matching tRNA anticodon. • By matching the codon and anticodons, amino acids can be dropped off in a specific order. • The Result: a unique protein for each unique gene.
Now, using pg. 244 in your book, turn your RNA sequence into protein. Start at the “start” codon! AUG GGA CUC GAC CAG UUA CAC GUG UAA Met - Gly - Leu - Asp - Gln - Leu - His - Val - Lys