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Translation

Translation . Protein Synthesis. What is translation?. The synthesis of a polypeptide from the code on the mRNA. Occurs on a ribosome. Transfer RNA. Carries amino acids to the ribsome Each tRNA is specific for the amino acid it carries. Can be used over and over again.

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Translation

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  1. Translation Protein Synthesis

  2. What is translation? • The synthesis of a polypeptide from the code on the mRNA. • Occurs on a ribosome

  3. Transfer RNA • Carries amino acids to the ribsome • Each tRNA is specific for the amino acid it carries. • Can be used over and over again. • Is complementary to mRNA • Anticodon – a nucleotide triplet on the end of the tRNA that is complementary to codon on the mRNA. This is where the tRNA and mRNA bind to each other.

  4. tRNA

  5. mRNA • mRNA is read one codon at a time. • Codon = 3 consecutive nucleotides • There are 64 different codons. • 1 codon = 1 amino acid

  6. Codons and Amino Acids

  7. Ribosomes • Made up two subunits – one large and one small. • The subunits are made up of rRNA and proteins. • Have 3 binding sites: • P site – holds tRNA that carries growing polypeptide • A site – holds tRNA that carries the amino acid that will be added. • E site – the exit site

  8. Ribsome Structure

  9. Steps of Translation Occurs in 3 stages: • Initiation • Elongation • Termination

  10. Initiation • mRNA, tRNA that has the first amino acid and the two ribosomal subunits join together. This forms a translation initiation complex. • This starts at the start codon, AUG. • The first amino acid will be Methione.

  11. Initiation Illustrated

  12. Elongation • Amino acids are brought in one at a time. • tRNA with next amino acid is brought into the A site. • Peptide bond is formed between the amino acids on the tRNAs at the A and P sites. • Ribosomal unit shifts toward the E site. The 1sttRNA is at the E site, 2ndtRNA is at the P site and the A site is now empty.

  13. Elongation Illustrated

  14. Elongation continued • The tRNA at the E site leaves to find another amino acid. • Elongation continues until a stop codon on the mRNA is reached.

  15. Termination • A stop codon is reached. (UAA, UAG or UGA) • A protein called a release factor binds to the stop codon and the polypeptide is freed from the ribosome.

  16. Termination Illustrated

  17. Termination Illustration Continued

  18. What happens next? • Proteins are sent to the Golgi Body for modification so that they can become funtional.

  19. Why does translation make you so blue?

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