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Semester 2, Day 7

Semester 2, Day 7. Transcription & Translation. Agenda. Study for DNA, RNA, Proteins, Semiconservative Replication Quiz Turn in homework: Section 11.1-11.3 Quiz for DNA, RNA, Proteins, Semiconservative Replication Translation and Transcription Lecture

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Semester 2, Day 7

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  1. Semester 2, Day 7 Transcription & Translation

  2. Agenda • Study for DNA, RNA, Proteins, Semiconservative Replication Quiz • Turn in homework: Section 11.1-11.3 • Quiz for DNA, RNA, Proteins, SemiconservativeReplication • Translation and Transcription Lecture • Translation and Transcription Activity • Work Time

  3. Central Dogma • Central Dogma: DNA codes for RNA which guides the synthesis of proteins. • DNA: “master blueprint”, contains all genetic info of an organism. Must be protected; therefore it never leaves the nucleus. • RNA: “temporary blueprint”, copies small portions of DNA and can leave nucleus to synthesize proteins at the ribosome. • Proteins: primary building block of organisms. A macromolecule made of linked monomers called amino acids. DNA RNA Protein Transcription “copy” Translation “interpret”

  4. Central Dogma • Transcription: DNA  mRNA • DNA helicase (enzyme) unwinds DNA strands. • RNA polymerase (enzyme) “reads” DNA template strand & synthesizes mRNA • Matches nitrogen bases on DNA to complementary RNA bases • 3. mRNA leaves nucleus through nuclear pore to the cytoplasm “messenger” template strand DNA Helicase nontemplate strand DNARNA A = U T = A C  G G  C Usually T in DNA, but RNA uses U instead! Image Source: biology.about.com

  5. Central Dogma codon • Translation: mRNA  Protein • mRNA travels through cytoplasm to ribosome (made of rRNA) • tRNAs bring amino acids to the ribosome • The ribosome matches tRNA anticodons to mRNA codons, which links amino acids together, creating a polypeptide (unfolded protein) • **Note: 20 different tRNA (one for each amino acid) Image Source: hyperphysics.phy-astr.gsu.edu

  6. Central Dogma Transcription “copy” Translation “interpret” Image Source: nnhsbiology.pbworks.com

  7. Central Dogma • How do you know what amino acid is brought by tRNA? Genetic Code Chart(uses codons from mRNA!) • AUG: methionine (START) • Begin decoding; start with methanine amino acid • UAA, UAG, UGA: STOP • End decoding; no additional amino acids **Note: Many types of codons (64 codons), but only 20 amino acids. Important when we learn about mutations! Image Source: waynesword.palomar.edu

  8. Image Source: www.contexo.info Central Dogma • Example: Folded into complex 3D shape  Protein!

  9. Central Dogma • What would the tRNA anticodons have been? • Remember!**The Genetic CodeChart uses CODONS,not anticodons. Codon mRNA: A U G U C U C A C A AA G A G tRNA: U A C A G A G U G U UU C U C Anticodon tRNA is a type of RNA, so it uses U, not T! His Met Amino Acids Glu Lys Ser Image Source: en.wikipedia.org

  10. Gummy DNA • Supplies: • Red Licorice = Deoxyribose sugar and phosphate backbone • Purple Licorice = Ribose sugar and phosphate backbone • Gummy Bears = Nitrogen bases • Hard Candies = Amino Acids to build Proteins • You should have 18 toothpicks • Break them in half • Choose 9 gummy bears with different colors • Red=Adenine, Yellow=Thymine, Orange=Cytosine, Green=Guanine • Don’t choose white! • Put 9 half-toothpicks in red licorice and attach gummy bears. This is one DNA strand. • Make the complementary DNA strand. A=T, CG • Attach strands together. This is what DNA looks like!

  11. Gummy Transcription • Transcription = “Copy” • Take your purple licorice and add 9 half-toothpicks • “Unzip” your DNA and take one of the strands • Find the matching RNA bases (not DNA)! • Red=Adenine • White=Uracil • Orange=Cytosine • Green=Guanine • Build the mRNA strand

  12. Gummy Translation • Translation = “Change” • Using your mRNA strand, find the codons (nitrogenous base triplets) • Use the genetic code chart to “translate” to amino acids • Have your tRNA bring in a hard candy representing the amino acids. If you have different amino acids, you should have different colors of hard candy. • Put amino acids together into a strand = Protein!

  13. Work Time • Annotate the packet • Sections 11.4-11.5 • Do all concept checks • Chapter 11 Review • #3-6, 12, 14, 15, 19, 20, 22-24

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