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AP Biology

AP Biology. Tests back today Curve was 12 points Grades on test haven’t had 12 points added (they are correct in ps ) Study guide changes rip out page 7 (that is a different chapter) Test is December 20. History of DNA. Griffith. Conclusion:. Phage. Hershey/Chase. Hershey/Chase.

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AP Biology

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  1. AP Biology • Tests back today • Curve was 12 points • Grades on test haven’t had 12 points added (they are correct in ps) • Study guide changes rip out page 7 (that is a different chapter) • Test is December 20

  2. History of DNA

  3. Griffith Conclusion:

  4. Phage

  5. Hershey/Chase

  6. Hershey/Chase

  7. Hershey/Chase Conclusion:

  8. Franklin

  9. Franklin

  10. Watson/Crick

  11. AP Biology • Review from last class • Continue DNA talk • Replication today

  12. Watson/Crick DNA Replication Semiconservative: when a double helix replicates, each of the daughter molecules has one old strand and one new

  13. Replication Vocab on Replication • Origin of replication- special sites where replication begins • Replication fork- a “bubble” where parental strands are unwound • Helicase- unzips parent strand • Single-stranded binding protein- binds to unpaired DNA to stabilize them • Topoisomerase- relieves strain from twisting

  14. Replication Vocab contd. • Primer- initial nucleotide is a short stretch of RNA • Primase- an enzyme that synthesizes the primer • DNA polymerase- catalyzes the synthesis of new DNA by adding nucleotides to a preexisting chain

  15. DNA 3’ vs 5’ The 5’ 3’ runs in the opposite direction as the: 3’ 5’ Antiparallel- the two strands of DNA are oriented in opposite directions to each other.

  16. DNA • DNA can ONLY add nucleotides from the 3’ side on parent Strand • DNA daughters are “built” from 5’ 3’

  17. DNA • Leading strand- the continuous strand • Lagging strand- the strand that is copied away from the fork • Lagging strands called- Okazaki fragments.

  18. DNA

  19. Chapter 17 • Gene expression and protein synthesis • Test next Thursday 

  20. Proteins • Proteins are link between genotype and phenotype • Gene expression- process by which DNA directs protein synthesis, includes two stages called transcription and translation DNA RNA Protein DNA

  21. Protein Review • Amino acids - building blocks of protein • Polymer - many building blocks covalently bonded • Peptide bonds- covalent bond between amino acids • 20 total amino acids

  22. DNA/RNA

  23. Protein Synthesis

  24. Codons • How many nucleotides could there be if: • Each kind of nucleotide base were translated into an amino acid? • If a two-letter sequence was in place? • If there were triplet bases?

  25. Codons • Codons – the mRNA nucleotide triplets, written normally in the 5’ 3’ direction • CCU • AUG • AGC • AGG

  26. Transcription Vocabulary: • RNA polymerase- separates DNA and joins RNA nucleotides together, nucleotide bases assemble in a 5’ 3’ direction (no primer required) • Promoter- When RNA polymerase initiates transcription sequence • Terminator- when RNA polymerase signals the end of transcription

  27. Transcription Steps of Transcription • Initiation- RNA synthesis begins • Elongation- the RNA strand gets bigger • Termination- the RNA transcript is released

  28. Transcription

  29. RNA Processing Pre-mRNA must be altered before it travels outside of the nucleus • Alternation of mRNA ends • 5’ cap – a modified guanine added to the 5’ end • Poly-A tail- 50-250 adenine nucleotides are added to the 3’ side

  30. RNA Processing Pre-mRNA must be altered before it travels outside of the nucleus • RNA splicing- removal of large portions of the RNA molecule (cut-and-paste) • This means that there are long noncoding portions of DNA are not coding for anything. • Introns - noncoding regions • Exons – coding regions

  31. Translation Vocabulary: • Anticodon- attached to tRNA molecules, a nucleotide triplet. Complementary to the mRNA codon • Wobble – the flexible base pairing at the third nucleotide position.

  32. Translation

  33. Translation

  34. Translation

  35. Translation

  36. Translation Steps of Translation • Initiation- brings together mRNA and tRNA to begin synthesizing proteins • Elongation – Amino acids are added • Termination – A stop codon reaches A site, and the amino acids (polypeptide) is released

  37. Translation

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