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From DNA to Polypeptide

From DNA to Polypeptide. Fun Times with the Double Helix. Get the most out of the lesson…. Set up notes page as shown Fold colored paper as shown Record new vocab words and review these at home Use different colored pencils. Why learn about DNA?. Itself is not alive…

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From DNA to Polypeptide

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  1. From DNA to Polypeptide Fun Times with the Double Helix

  2. Get the most out of the lesson… • Set up notes page as shown • Fold colored paper as shown • Record new vocab words and review these at home • Use different colored pencils

  3. Why learn about DNA? • Itself is not alive… • Exists for only one reason… to make more DNA • 2 meters squeezed into each cell ~2o million km! • Holds the instructions to make and maintain you. • Contains roughly 3.2 billion letters- 103,480,000,000 combinations • Is 99.9% identical to everyone else’s DNA • Is 0.1% completely and utterly unique to you.

  4. History • James Watson and Francis Crick- discovered the structure of DNA– the double helix

  5. The Monumental Discovery • http://www.youtube.com/watch?v=sf0YXnAFBs8

  6. Monomers and Polymers Nucleic Acid Nucleotides

  7. Nucleotides • 4 types of nucleotides, A,T, C, G • Complementary base pairing: • A = T • C = G

  8. DNA Structure

  9. DNA Replication • DNA inside nucleus makes copy of itself during _____ stage of _______________. • Part of the DNA helix unwinds (by enzyme “helicase”) when H+ bonds between nitrogenous bases are broken.

  10. DNA Replication

  11. Step 1

  12. DNA Replication • Each strand serves as a pattern for a new strand of DNA • Enzyme DNA Polymerase moves along each separate strand and matches bases (A, C, T, G) on each strand to a new base that is “floating” inside the nucleus.

  13. Step 2

  14. DNA Replication • H+ bonds reform between bases…

  15. Semi-conservative • Each strand of DNA serves as a template for a new strand. • The replicated DNA is made of one old strand and one new strand

  16. A New Strand is “born”

  17. Watch the process http://www.youtube.com/watch?v=4jtmOZaIvS0&feature=related

  18. Watch the process http://www.youtube.com/watch?v=d1UPf7lXeO8&feature=related

  19. Interpreting DNA How does a cell interpret DNA? Simulation: • Group A: Design a structure using all the materials in the ziplock bag. • Devise a way to communicate with Group B how to duplicate this design… no words, no pictures… all blueprints stay at Group A site.

  20. Transcription From DNA to messenger RNA

  21. DNA to RNA • Making a protein (polypeptide) begins with making mRNA (messengerRNA) inside the nucleus. • RNA is also a “nucleic acid” • is single-stranded • has “uracil” (U) instead of thymine • has 5C sugar “ribose”

  22. Transcription • Step 1: DNA strand separates at a gene spot on DNA. • Only 1 strand of DNA will serve as a template- starts at a “promoter” • Step 2: Enzyme “RNA polymerase” matches RNA bases with DNA bases: A, U, C, G • Step 3: Enzymes link RNA nucleotides together into a single-strand of RNA.

  23. Transcription • Step 4: mRNA leaves nucleus with code for protein and moves to ribosomes where the protein will be made. • Important editing is required of mRNA: • Introns: cut-out connected sequences • Exons: expressed sequences spliced together- final edited RNA

  24. Transcription

  25. Transcription in action • http://www.youtube.com/watch?v=5MfSYnItYvg&feature=relmfu

  26. Types of RNA • There are actually many types of RNA. • In most cells three kinds of RNA are critical to the making of proteins. • mRNA – “messenger RNA” carry copies of the instructions for the proteins from the DNA to the ribosomes • rRNA – “ribosomal RNA” are part of the ribosomal structure • tRNA - “transfer RNA” transfers the amino acids to the ribosomes to make the protein

  27. MODEL TIME !

  28. Translation: mRNA to Protein • Making of proteins is called “protein synthesis” • Instructions for each protein comes from the mRNA in 3-base messages called “codons” • Codons are translated in the ribosomes. mRNA attaches to the ribosome (rRNA)

  29. Translation: mRNA to Protein • “Translation” is the decoding of the message from the mRNA into a polypeptide chain (protein). • The tRNA is a cloverleaf-shaped molecule that has on one end a complementary “anticodon” and on the other end an amino acid. • Example: codon AAA, anticodon UUU or lysine

  30. Translation

  31. The Genetic Code • As the codons from the mRNA are “read” inside the ribosome and the tRNA delivers one amino acid at a time… • these amino acids bond together with “polypeptide” bonds … • the “language” of mRNA instructions is called the Genetic Code… • How can 3 base codons make 20 amino acids? (4 x 4 x 4) = 64 possibilities

  32. The Genetic Code

  33. The Genetic Code

  34. From DNA to Protein http://www.youtube.com/watch?v=41_Ne5mS2ls&NR=1

  35. MODEL TIME!

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