Dna protein


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Dna protein

  1. 1. DNA Transcription & Protein Translation Honors Biology SOL.BIO.6f
  2. 2. Today’s Objectives <ul><li>TSW investigate and understand common mechanisms of protein synthesis. </li></ul>
  3. 3. DNA Transcription <ul><li>DNA must be copied to messenger RNA (mRNA) </li></ul><ul><li>mRNA goes from nucleus to the ribosomes in cytoplasm </li></ul><ul><li>mRNA complements known as codons </li></ul><ul><ul><li>Only 3 nucleotide “letters” long </li></ul></ul><ul><li>Remember RNA has uracil (U) instead of thymine (T)! </li></ul>
  4. 4. Transcription – Step I Template DNA Strands A C G T A T C G C G T A T G C A T A G C G C A T
  5. 5. Transcription – Step II Template DNA is Matched Up with Complementary mRNA Sequences A C G T A T C G C G T A U G C A U A G C G C A U
  6. 6. Transcription – Step III mRNA leaves nucleus and goes to ribosomes A new complementary RNA strand is made (rRNA) U G C A U A G C G C A U A C G U A U C G C G U A
  7. 7. Transcription Reminders <ul><li>The template strand is the DNA strand being copied </li></ul><ul><li>The rRNA strand is the same as the DNA strand except Us have replaced Ts </li></ul>
  8. 8. Protein Translation <ul><li>Modified genetic code is “translated” into proteins </li></ul><ul><li>Codon code is specific, but redundant! </li></ul><ul><ul><li>20 amino acids </li></ul></ul><ul><ul><li>64 triplet (codon) combinations </li></ul></ul>
  9. 9. tRNA in cytoplasm has a codon attached to an amino acid
  10. 10. tRNA structure <ul><li>3-base code (triplet) is an “anticodon” </li></ul><ul><li>Protein molecule </li></ul><ul><li>Attached amino acid that is carried from cytoplasm to ribosomes </li></ul>
  11. 11. Protein Synthesis <ul><li>Start: Ribosome binds to mRNA at start codon (AUG) </li></ul><ul><li>Elongation: </li></ul><ul><ul><li>tRNA complexes bind to mRNA codon by forming complementary base pairs with the tRNA anticodon </li></ul></ul><ul><ul><li>The ribosome moves from codon to codon along the mRNA. </li></ul></ul><ul><ul><li>Amino acids are added one by one </li></ul></ul><ul><li>Release: release factor binds to the stop codon </li></ul>