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 Thomas Morgan 1900 Frederick Griffith 1928
Oswald Avery 1940
Hershey and Chase 1952
Erwin Chargaff 1950
Rosalind Franklin 1950
Watson and Crick 1953
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. DNA Replication Watson/Crick
Semiconservative: when a double helix replicates, each of the daughter molecules has one old strand and one new

13. Vocab on Replication 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. Vocab contd. Replication
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’
3’ ’
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 DNA RNA Double helix Single strand A,T,C,G A,U,C,G
Deoxyribose sugar
Ribose sugar
mRNA
rRNA
tRNA

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. Vocabulary: Transcription
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. 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 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. Vocabulary: Translation
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. Steps of Translation 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