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Translation

Translation. Chapter 10: DNA, RNA and Protein Synthesis. The Genetic Code. The Genetic Code is the term for the rules that relate how a sequence of nitrogenous bases in nucleotides corresponds to a particular amino acid.

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Translation

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  1. Translation Chapter 10: DNA, RNA and Protein Synthesis

  2. The Genetic Code • The Genetic Code is the term for the rules that relate how a sequence of nitrogenous bases in nucleotides corresponds to a particular amino acid. • In the Genetic Code, three adjacent nucleotides (“letters”) in mRNA specify an amino acid (“word”) in a polypeptide.

  3. Codon • A sequence of three nucleotides that encode for an amino acid or signifies a start or stop signal. Examples: UUU = phenylalanine AUG = start

  4. The Genetic Code

  5. Examine the sequence of three bases: UAC

  6. Codons • There are 64 possible codons corresponding to 20 amino acids • Each amino acid has more than one possible codon. • There are Start and Stop signals built into the code. • The Start codon corresponds to the amino acid methionine.

  7. Flow of Information • The sequence of nitrogenous bases in DNA becomes complementary to the sequence of bases in the mRNA molecule during TRANSCRIPTION. • tRNA molecules bring amino acids to the ribosome and match up their complementary bases to the mRNA molecule during TRANSLATION.

  8. Translation • The making of a protein by stringing together amino acids to make a polypeptide chain. • Information flows from DNA to mRNA and then tRNA brings the corresponding amino acid. • Peptide bonds are formed between adjacent amino acids and a polypeptide chain is formed.

  9. Translation - What is it? The making of a protein • Where does it take place? Prokaryotes = cytoplasm Eukaryotes = cytoplasm • What is needed? mRNA, 2 ribosomal subunits, tRNA and amino acids

  10. Steps of Translation • Initiation: The ribosomal subunits, the mRNA, and the tRNA carrying methionine bind together.

  11. Initiation

  12. Elongation • The tRNA carrying the amino acid sequence specified by the next codon binds to the codon. • A peptide bond forms between adjacent amino acids • The ribosome moves the tRNA and mRNA.

  13. Elongation

  14. (Continued Elongation) • The first tRNA detaches and leaves its amino acid behind. • Elongation continues. • The polypeptide chain continues to grow.

  15. Elongation (continued)

  16. Termination • The process ends when a stop codon is reached. • A stop codon is one for which there is no tRNA molecule that has a complementary anticodon.

  17. Disassembly • The ribosome complex falls apart. The newly made polypeptide is released.

  18. Summary • Information flows from DNARNAProteins • RNA serves as the intermediary between DNA and proteins. • There are three types of RNA. mRNA, rRNA and tRNA. • The Genetic Code represents 64 possible codons corresponding to 20 different amino acids, start signal and stop signals. • The process of TRANSLATION takes place within the cytoplasm on a ribosome. • The process of TRANSLATION involves: initiation, elongation and termination.

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