PROTEIN SYNTHESIS. DNA and Genes DNA DNA contains genes, sequences of nucleotide bases These Genes code for polypeptides (proteins) Proteins are used.

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  • DNA and Genes

    copyright cmassengale

  • DNADNA contains genes, sequences of nucleotide basesThese Genes code for polypeptides (proteins)Proteins are used to build cells and do much of the work inside cells

  • Genes & ProteinsProteins are made of amino acids linked together by peptide bonds20 different amino acids exist

  • PolypeptidesAmino acid chains are called polypeptides

  • DNA Begins the ProcessDNA is found inside the nucleusProteins, however, are made in the cytoplasm of cells by organelles called ribosomesRibosomes may be free in the cytosol or attached to the surface of rough ER

  • Starting with DNADNA s code must be copied and taken to the cytosolIn the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins)This process is called PROTEIN SYNTHESIS

  • RNA

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  • Roles of RNA and DNADNA is the MASTER PLAN

    RNA is the BLUEPRINT of the Master Plan

  • RNA Differs from DNARNA has a sugar riboseDNA has a sugar deoxyribose

  • Other DifferencesRNA contains the base uracil (U)DNA has thymine (T)RNA molecule is single-strandedDNA is double-strandedDNA

  • Structure of RNA

  • . Three Types of RNAMessenger RNA (mRNA) copies DNAs code & carries the genetic information to the ribosomesRibosomal RNA (rRNA), along with protein, makes up the ribosomesTransfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

  • Messenger RNALong Straight chain of NucleotidesMade in the NucleusCopies DNA & leaves through nuclear poresContains the Nitrogen Bases A, G, C, U ( no T )

  • Messenger RNA (mRNA)Carries the information for a specific proteinMade up of 500 to 1000 nucleotides longSequence of 3 bases called codonAUG methionine or start codonUAA, UAG, or UGA stop codons

  • Ribosomal RNA (rRNA)rRNA is a single strand 100 to 3000 nucleotides longGlobular in shapeMade inside the nucleus of a cellAssociates with proteins to form ribosomesSite of protein Synthesis

  • The Genetic CodeA codon designates an amino acidAn amino acid may have more than one codonThere are 20 amino acids, but 64 possible codonsSome codons tell the ribosome to stop translating

  • The Genetic Code Use the code by reading from the center to the outsideExample: AUG codes for Methionine

  • Name the Amino AcidsGGG?UCA?CAU?GCA?AAA?

  • Remember the Complementary BasesOn DNA: A-T C-GOn RNA: A-U C-G

  • Transfer RNA (tRNA)Clover-leaf shapeSingle stranded molecule with attachment site at one end for an amino acidOpposite end has three nucleotide bases called the anticodon

  • Transfer RNA

  • Codons and AnticodonsThe 3 bases of an anticodon are complementary to the 3 bases of a codonExample: Codon ACU Anticodon UGAUGAACU

  • Transcription and Translation

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  • Pathway to Making a ProteinDNA mRNA

    tRNA (ribosomes)


  • Protein Synthesis The production or synthesis of polypeptide chains (proteins) Two phases: Transcription & Translation mRNA must be processed before it leaves the nucleus of eukaryotic cells

  • DNA RNA ProteinEukaryotic Cell

  • TranscriptionThe process of copying the sequence of one strand of DNA, the template strandmRNA copies the template strandRequires the enzyme RNA Polymerase

  • Question:What would be the complementary RNA strand for the following DNA sequence?



  • TranscriptionDuring transcription, RNA polymerase binds to DNA and separates the DNA strandsRNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA

  • mRNA TranscriptmRNA leaves the nucleus through its pores and goes to the ribosomes

  • TranslationTranslation is the process of decoding the mRNA into a polypeptide chainRibosomes read mRNA three bases or 1 codon at a time and construct the proteins

  • TranscriptionTranslation

  • End Product The Protein!The end products of protein synthesis is a primary structure of a proteinA sequence of amino acid bonded together by peptide bonds

  • Messenger RNA (mRNA)

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    ************Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.**********************Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein.***


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