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Chapter 3, part C

Chapter 3, part C

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Chapter 3, part C

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  1. Chapter 3, part C Central Dogma of Molecular Biology From Genes to Protein

  2. Central Dogma of Molecular Biology mRNA Eukaryotic Cell ribosome Transcription: synthesis of mRNA from DNA by RNA polymerase protein - Two steps: 1. creating a 1o mRNA transcript 2. RNA processing (editing) to create 2o mRNA transcript Translation: ribosomes link together amino acids to create a polypeptide from the 2o mRNA code Polypeptide then coils into a specific 3-D shape to form a functional protein transcription mRNA 1o transcript RNA Processing mRNA 2o transcript ribosome translation polypeptide

  3. Triplet-code Instructions for a polypeptide DNA A C C A A A C C G A G T Transcription U G G U U U G G C U C A mRNA Translation trp phe gly ser polypeptide

  4. Figure 3.34b: An overview of transcription, p. 106. Coding strand RNA polymerase Unwinding of DNA Rewinding of DNA Template strand RNA nucleotides mRNA RNA-DNA hybrid region (b)

  5. 3 RNA Players Involved in Translation Central Dogma tRNA = type of RNA that carries the amino acids to the ribosome rRNA = RNA that, combined with protein, makes up the structural component of a ribosome mRNA = DNA transcript

  6. Redundancy in AA • Notice…several codons code for the same AA Redundancy helps to minimize errors in protein synthesis due to mutations

  7. Figure 3.36: Translation, p. 108. Nucleus RNA polymerase mRNA 1 mRNA transcription and processing mRNA moves out of nucleus Template strand of DNA Amino acids Released mRNA tRNA ribosome Codon 2 U Amino acid is attached to each species of tRNA by an enzyme A U C G C C A U U U A C G G E P A tRNA anticodon G U A A A U Ile Ala Phe Ile 4 A growing polypeptide chain of amino acids is created Polypeptide eventually folds into a specific protein Ser 3 ribosome translates mRNA by moving along the mRNA and matching codons with anticodons of tRNA tRNA carry amino acids to be peptide bonded together Gly Met

  8. Figure 3.37: Polyribosomes, p. 109. Ribosome mRNA 1 1 2 Peptide chain mRNA Ribosome 2 1 3 Completed polypeptide 3 2 4 1 4 1 3 5 2 1 Ribosomal units (a) (b)

  9. Figure 3.38: Information transfer from DNA to RNA, p. 110. DNA molecule Gene 3 Gene 1 Gene 5 Triplets 1 2 3 4 5 6 7 8 9 DNA base sequence (triplets) of the gene coding for the synthesis of a particular polypeptide chain Codons 1 2 3 4 5 6 7 8 9 Base sequence (codons) of the transcribed mRNA Consecutive base sequences of tRNA anticodons capable of recognizing the mRNA codons calling for the amino acids they transport tRNA Amino acid sequence of the polypeptide chain Met Pro Ser Leu Lys Gly Arg Phe Stop; detach Start

  10. Watch these real-time videos on DNA transcription and translation…Totally Cool Dude!