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Transcription and Translation. DNA’s destiny!. What does DNA really do?. The DNA code must code for something right??? So what IS IT???? The DNA alphabet essentially codes for amino acids Which are the building blocks for……. PROTEINS!!!!!!!!!!
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Transcription and Translation DNA’s destiny!
What does DNA really do? • The DNA code must code for something right??? So what IS IT???? • The DNA alphabet essentially codes for amino acids • Which are the building blocks for……. PROTEINS!!!!!!!!!! • This occurs in several organized steps IN 2 PHASES
From DNA to Protein: the 2 phases • PHASE 1: • Transcription • DNA IS TRANSCRIBED INTO READABLE FORM (mRNA) • PHASE 2: • Translation • mRNA IS TRANSLATED (tRNA) TO CODE FOR AMINO ACIDS
Phase 1: Transcription • Occurs INSIDE THE NUCLEUS • DNA strands separate • Complimentary RNA bases take their places along DNA with the help of enzymes • RNA bases are A, C, G, and U (uracil) • U instead of T! • This creates an mRNA strand Let’s see this in action!
Phase 1: Transcription • Let’s practice making a complimentary mRNA from a DNA strand! DNA mRNA
Proteins…the ultimate result • Long chains formed by 20 different amino acids • Protein shape is determined by DNA sequence! • DNA transcribed to mRNA • mRNA is eventually translated by tRNA (transfer RNA) and codes for amino acids!
Proteins…the ultimate result • 3 mRNA bases will code for a specific amino acid. • Ex. GCU codes for Alanine • This is called a CODON • Each amino acid has more than one codon! • Polypeptide: • String of amino acids • Let’s look at the mRNA we transcribed earlier!
Proteins…the ultimate result • The strand we made earlier is: G C U A A U C U A • If 3 bases code for an amino acid, how many amino acids are coded in our strand? 3 of course! G C U | A A U | C U A Alanine | Asparagine | Leucine • Coding and stringing amino acids together is called TRANSLATION!
Phase 2: Translation • mRNA is shipped out of nucleus for translation • **Review** Which organelle is in charge of protein synthesis?? (Hint: very tiny little buggers) RIBOSOMES! • mRNA binds to a ribosome for translation!
Phase 2: Translation • mRNA binds to ribosome • Ribosome translates the codons on the mRNA • This signals a tRNA to bring the correct amino acid • tRNA drops off the amino acid
Phase 2: Translation • Ribosome moves to next codon • Another tRNA comes with next amino acid • Amino acids are connected by PEPTIDE BONDS • This continues until all of the mRNA has been read and a STOP codon is reached. • End result: a protein!!!!!!!!! Let’s return to the transcription/translation site!