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Download Bio Jan 26 2017
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Central Dogma • DNA codes for RNA, RNA codes for proteins Translation • Changing Languages • Nucleic acids to protein • DNA to RNA to amino acids Translation • mRNA leaves the nucleus • Small subunit of ribosome binds to START codon • Large subunit binds to that… • And the process starts Translation • Codon – a three-base sequence on mRNA that codes for an amino acid • Proteins are made of amino acids • Many amino acids in a chain => fold up => PROTEIN! Amino Acids Translation • What does AUG code for? • Also START! • GGU? • GGA? • UGA? Translation • How many amino acids? • How many codons? • Implications for mutations? Translation • How many proteins can you make with 20 amino acids? • What are the limits? Translation • mRNA • rRNA – what the ribosome is made of • tRNA – brings the amino acids to the ribosome Translation • After the ribosome has formed on the mRNA • tRNA molecules will bring the amino acids • Each tRNA molecule has a three-base sequence called the anticodon • This sequence is complementary to the codon • They form hydrogen bonds • Amino acid attachment site • Anticodon – binds to codon on mRNA Translation • Follow along on 368-369 fig 13-7 • Once the codon and anticodon have bonded, the ribosome moves down the mRNA • Another tRNA enters the A site, • As the ribosome moves down, the amino acid(s) get transferred to the “new” tRNA now in the P site Translation • The small subunit binds to the mRNA with the start codon in the P site Translation Translation • Large subunit attaches • The next tRNA brings in the amino acid Translation Translation • The first amino acid (Methionine) gets transferred and attached to the next amino acid (Leucine in this example) • The ‘first’ tRNA leaves • The ribosome moves down the mRNA molecule • The tRNA then gets ‘recharged’ with another amino acid Translation • The ribosome moves down the mRNA molecule • And the process continues… Translation • The ribosome moves down the mRNA molecule • And the process continues… • Until the stop codon is reached Translation https://www.youtube.com/watch?v=TfYf_rPWUdY tRNA • How does the tRNA get recharged? • Synthetase! tRNA tRNA • 20 amino acids • How many different synthetases? • How does the amino acid/synthetase know it’s the right amino acid? Mutations • What are… • Point Mutations? • Substitution? • Insertions, Deletions? • When, Where, HOW? • Finish for homework – pages 307-308
