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PROTEIN SYNTHESIS THE FORMATION OF PROTEINS USING THE INFORMATION CODED IN DNA WITHIN THE NUCLEUS AND CARRIED OUT BY RNA IN THE CYTOPLASM.

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Presentation on theme: "PROTEIN SYNTHESIS THE FORMATION OF PROTEINS USING THE INFORMATION CODED IN DNA WITHIN THE NUCLEUS AND CARRIED OUT BY RNA IN THE CYTOPLASM."— Presentation transcript:

1 PROTEIN SYNTHESIS THE FORMATION OF PROTEINS USING THE INFORMATION CODED IN DNA WITHIN THE NUCLEUS AND CARRIED OUT BY RNA IN THE CYTOPLASM

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

3 GENETIC CODE n TRANSFERS INFORMATION n BUILT INTO DNA ARRANGEMENT OF NITROGEN BASES n TRANSFERRED TO RNA DURING TRANSCRIPTION DNA IS TEMPLATE n 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 n IS A THREE BASE SEQUENCE OF NITROGEN BASES ON mRNA n EACH CODON IS SPECIFIC FOR A SINGLE AMINO ACID n ATTRACTS A COMPLIMENTARY SEQUENCE OF BASES ON tRNA n INITIATION AND TERMINATION CODONS START AND STOP TRANSLATION

5 64 CODONS FOR 20 AMINO ACIDS n EACH AMINO ACID HAS SEVERAL CODONS DIFFER FROM EACH OTHER ONLY IN THE THIRD BASE n SOME CODONS DO NOT CODE AMINO ACIDS (INITIATION AND TERMINATION) n CODE IS UNIVERSAL - USED BY ALL LIVING THINGS

6

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

8 TRANSLATION THE PROCESS OF ASSEMBLING PROTEINS FROM THE INFORMATION CODED IN THE mRNA

9 AMINO ACID SITE ANTICODON tRNA HYDROGEN BONDS

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

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

12 PROTEIN ASSEMBLY ON THE RIBOSOMES

13 OVERVIEW OF PROTEIN SYNTHESIS n ORDER OF AMINO ACIDS IS DETERMINED BY ORDER OF BASES IN mRNA n ORDER OF BASES IN mRNA IS DETERMINED BY ORDER OF COMPLIMENTARY BASES IN DNA n THE REGION OF DNA WHICH CODES FOR THE SEQUENCE OF AMINO ACIDS IN A SINGLE POLYPEPTIDE IS CALLED A GENE n MANY GENES MAY BE REQUIRED TO FORM A SINGLE PROTEIN

14 Primary Structure of a Protein The 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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