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PROTEIN SYNTHESIS

PROTEIN SYNTHESIS. THE FORMATION OF PROTEINS USING THE INFORMATION CODED IN DNA WITHIN THE NUCLEUS AND CARRIED OUT BY RNA IN THE CYTOPLASM. PROTEIN STRUCTURE. ORGANISMS ARE COMPOSED OF FROM SEVERAL HUNDRED TO SEVERAL THOUSAND DIFFERENT PROTEINS

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PROTEIN SYNTHESIS

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  1. PROTEINSYNTHESIS THE FORMATION OF PROTEINSUSING THE INFORMATION CODED IN DNAWITHIN THE NUCLEUS AND CARRIED OUT BY RNA IN THE CYTOPLASM

  2. PROTEINSTRUCTURE • ORGANISMS ARE COMPOSED OF FROM SEVERAL HUNDRED TO SEVERAL THOUSAND DIFFERENT PROTEINS • EACH PROTEIN IS A POLYMER KNOWN AS A POLYPEPTIDE • EACH POLYPEPTIDE CONSISTS OF A SPECIFIC SEQUENCE OF AMINO ACIDS • ONLY 20 AMINO ACIDS ARE USED • EACH PROTEIN MAY BE COMPOSED OF THOUSANDS OF INDIVIDUAL AMINO ACID RESIDUES • AMINO ACIDS MUST BE ARRANGED IN A SPECIFIC SEQUENCE TO INSURE PROPER FUNCTION • SEQUENCE DETERMINES THE SHAPE -- SHAPE DETERMINES FUNCTION

  3. GENETIC CODE • TRANSFERS INFORMATION • BUILT INTO DNA • ARRANGEMENT OF NITROGEN BASES • TRANSFERRED TO RNA • DURING TRANSCRIPTION • DNA IS TEMPLATE • REQUIREMENTS OF A CODE • MUST BE ABLE TO CODE FOR 20 AMINO ACIDS • ONE BASE = 4 CODONS • TWO BASES = 16 CODONS • THREE BASES = 64 CODONS

  4. CODONS • IS A THREE BASE SEQUENCE OF NITROGEN BASES ON mRNA • EACH CODON IS SPECIFIC FOR A SINGLE AMINO ACID • ATTRACTS A COMPLIMENTARY SEQUENCE OF BASES ON tRNA • INITIATION AND TERMINATIONCODONS START AND STOP TRANSLATION

  5. 64 CODONS FOR20 AMINO ACIDS • EACH AMINO ACID HAS SEVERAL CODONS • DIFFER FROM EACH OTHER ONLY IN THE THIRD BASE • SOME CODONS DO NOT CODE AMINO ACIDS (INITIATION AND TERMINATION) • CODE IS UNIVERSAL - USED BY ALL LIVING THINGS

  6. RNA • mRNA • CARRIES CODON SEQUENCE • FORMED FROM DNA SEQUENCE DURING TRANSCRIPTION • DETERMINES ORDER OF AMINO ACIDS IN PROTEIN • tRNA • TRANSPORTS AMINO ACID TO mRNA • SPECIFIC AMINO ACID SITE AT ONE END • THREE BASE COMPLIMENTARY ANTICODON AT THE OTHER END

  7. TRANSLATION THE PROCESS OF ASSEMBLING PROTEINS FROM THE INFORMATION CODED IN THE mRNA

  8. AMINO ACID SITE HYDROGEN BONDS tRNA ANTICODON

  9. EACH tRNA IS SPECIFIC FOR A CERTAIN AMINO ACID TRANSPORTS AMINO ACIDS TO RIBOSOME FOR PROTEIN SYNTHESIS THE ANTICODON END BONDS TO THE mRNA

  10. ASSEMBLY OF A POLYPEPTIDE • BEGINS WHEN RIBOSOME ATTACHES TO THE AUGCODON • AUG CODON PAIR WITH THE UAC ANTICODON ON A tRNA CARRYING METHIONINE (ALWAYS FIRST) • METHIONENE IS LATER REMOVED • TRANSLATION OCCURS SIMULTANEOUSLY AT MANY RIBOSOMES USING THE SAME mRNA (ASSEMBLY LINE FASHION) • THE RIBOSOME MOVES ALONG THE STRAND EACH CODON IS PAIRED WITH ITS COMPLIMENTARY ANTICODON AND AN AMINO ACID IS ADDED TO THE CHAIN • AN ENZYME IN RIBOSOME CATALYZES THE BONDING BETWEEN AMINO ACIDS FORMING PEPTIDE BONDS • CONTINUES UNTIL THE RIBOSOME REACHES A TERMINATION CODON THEN THE mRNA IS RELEASED • POLYPEPTIDE IS COMPLETE

  11. PROTEIN ASSEMBLY ON THE RIBOSOMES

  12. OVERVIEW OF PROTEIN SYNTHESIS • ORDER OF AMINO ACIDS IS DETERMINED BY ORDER OF BASES IN mRNA • ORDER OF BASES IN mRNAIS DETERMINED BY ORDER OF COMPLIMENTARY BASES IN DNA • THE REGION OF DNA WHICH CODES FOR THE SEQUENCE OF AMINO ACIDS IN A SINGLE POLYPEPTIDE IS CALLED A GENE • MANYGENES MAY BE REQUIRED TO FORM A SINGLE PROTEIN

  13. Primary Structure of a ProteinThe primary structure of a protein is its amino acid sequence, formed when a peptide bond joins the carboxyl group (one Carbon atom, two Oxygen atoms, and a Hydrogen atom) of one amino acid to the amino group (N) of another. A long chain forms from many amino acids, with one molecule of water given off with the formation of each peptide “link.” Microsoft Illustration

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