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Bell ringer: Briefly describe DNA transcription and translation. PowerPoint Presentation
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Bell ringer: Briefly describe DNA transcription and translation.

Bell ringer: Briefly describe DNA transcription and translation.

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Bell ringer: Briefly describe DNA transcription and translation.

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  1. Bell ringer:Briefly describe DNA transcription and translation.

  2. Comparing DNA and RNA

  3. Transcription + Translation =Protein Synthesis

  4. Transcription • Takes place in the nucleus • RNA polymerase unwinds helix • One strand of DNA acts as a template for mRNA (messenger RNA) • Promoter: marks where transcription starts • Intron: non-coding region, becomes pre-mRNA • Exon: coding region, becomes mature mRNA • Terminator: marks where transcription ends • After transcription is complete, the mRNA molecule detaches from the DNA and leaves the nucleus through pores • DNA helix reforms

  5. Transcription

  6. Translation • Takes place at the ribosome (made of rRNA) in the cytoplasm • tRNA (transfer RNA) carries anti-codons to ribosome where it is matched with a codon • Activation – start codon AUG • Codon-anticodon binding leads to polypeptide formation

  7. Triplets, codons and anti-codons,OH MY! • Triplet = group of three DNA nucleotides • Codon = group of three mRNA nucleotides • Anti-codon = group of three tRNA nucleotides • There are 64 anti-codons • There are 20 amino acids

  8. One Gene = One PolypeptideHypothesis • Theory: one gene is transcribed and translated to produce one polypeptide • Some proteins are composed of more than one polypeptide; this theory says that each polypeptide has its own gene • Example: hemoglobin – composed of four polypeptides (two copies of two types), each polypeptide has its own gene.

  9. Exceptions to the theory- • Some genes code for types of RNA that do not produce polypeptides • Some genes control the expression of other genes