DNA, RNA, & PROTEIN SYNTHESIS

1. If you were going to build something, what is the most important item that you would need? Explain why in at least 5 coherent sentences.

2. DNA, RNA, & PROTEIN SYNTHESIS

3. DNA DISCOVERY

4. DNA DISCOVERY Frederick Griffith-British • Studied the cause of pneumonia and possible vaccines. • Discovered two strains, S and R. • S-strain is live and causes disease. Named for smooth sugar-coat colonies. • R-strain does not cause disease and has rough colonies without a sugar-coat.

6. Griffith’s Experiment Observation: Organisms are able to pass on their traits to their offspring according to the Laws of Genetics as developed by Gregor Mendel. Question: What, within cells, serves as the genetic code material?

7. Griffith’s Experiment Hypothesis: • By manipulating exposure to different strains of bacteria, the specific chemical within cells that serves as the genetic material will be isolated.

8. Griffith’s Experiment Procedure: • Griffith injected some of the R-strain bacteria into mice. • What do you think happened?

9. Griffith’s Experiment • Griffith injected some of the S-strain bacteria into mice. • What do you think happened?

10. Griffith’s Experiment • Griffith knew that polysaccharides are not affected by heat, so he used heat to kill some of the S-strain bacteria and then injected them into mice. • What do you think happened?

11. Griffith’s Experiment • Keep in mind that neither dead S-strain nor live R-strain bacteria killed the mice. • Griffith then mixed some of the heat-killed S-strain and some of the live R-strain bacteria and then injected them into mice. • What do you think happened?

12. Griffith’s Experiment Conclusion: • The polysaccharide coating is not the genetic material. • When mixed, the R-strain bacteria were able, somehow, to absorb genetic material from the dead S-strain and turn into S-strain bacteria. • This ability was subsequently named transformation.

13. Griffith’s Experiment Theory: A specific chemical controlled the transformation of cells.

14. DNA DISCOVERY Oswald Avery-American • Expanded on Griffith’s experiments. Observation: A specific chemical controls transformation. Question: What chemicals are present in cells that can control transformation? Hypothesis: Either protein, RNA, or DNA control cell transformation.

15. AVERY’S EXPERIMENT Procedure • Using live S cells, Avery separately destroyed the proteins, RNA, and then DNA. • These separate batches were mixed with R cells again and injected into the mice.

16. AVERY’S EXPERIMENT • R-cell with no-protein S cells = dead mice. • R-cell with no-RNA S cells = dead mice. • R-cell with no-DNA S cells = normal mice.

17. AVERY’S EXPERIMENT Conclusion: Without DNA, the S cells could not transform the R cells. DNA must be the transforming agent.

18. DNA DISCOVERY Hershey-Chase Experiment- Americans • Set out to determine if DNA or proteins were hereditary material in viruses. Observation: Previewed Griffith/Avery experiment results.

19. HERSHEY-CHASE EXPERIMENT Question: What chemical allows a virus to infect a bacterium? Hypothesis: If DNA and proteins are chemically labeled, then the hereditary chemical will show up in the reproduced cells.

20. HERSHEY-CHASE EXPERIMENT Experiment: • Labeled virus proteins with radioactive sulfur. • Labeled virus DNA with radioactive phosphorus. • Allowed each sample to separately infect E. coli. • Once viruses are removed from the bacterium, the bacterial cells could be tested for each radioactive sample.

22. HERSHEY-CHASE EXPERIMENT Conclusion: The DNA had completely transferred, while trace amounts of protein were present in the new cells. DNA…. -is the hereditary material in viruses. -Controls and determines the traits of an organism -Maintains control by producing proteins Proteins control all body processes.

23. Discovery of DNA • What makes the S strain bacteria virulent? • Why was Griffith’s Fourth experiment so important? • What did the Hershey-Chase experiment prove? • According to Avery, what is the role of DNA during Griffith’s experiments? • List the steps of the Scientific Method.

24. DNA STRUCTURE

25. DNA STRUCTURE • Consists of repeating subunits called nucleotides • Nucleotide parts are all held together with covalent bonds • Nucleotides have 3 parts: • SUGAR • NITROGENOUS BASE • PHOSPHATE GROUP

26. DNA Nucleotide

27. DNA STRUCTURE • Sugar: Deoxyribose, a 5 carbon sugar • Phosphate Group: One phosphorus atom with four oxygen atoms. • The phosphate attaches to the deoxyribose at the methyl group. • This forms the backbone of DNA.

28. DNA STRUCTURE • Nitrogen Bases: • Adenine, Thymine, Guanine, and Cytosine • Nitrogen bases are carbon rings with random nitrogen atoms • Purines= double-ringed bases, Adenine and Guanine • Pyrimidines= single-ringed bases, Thymine and Cytosine

29. DNA STRUCTURE

30. DNA STRUCTURE

31. DNA STRUCTURE • Nitrogen bases stick out to the inside, toward each other. • Adenine always pairs with Thymine, and Cytosine always pairs with Guanine. • The base pairs are held together with weak hydrogen bonds. • The percentage of Adenine always equals the percent of Thymine; Guanine percentage always equals Cytosine percentage.

32. Base Pairing Stars represent hydrogen bonds

33. DNA STRUCTURE Two single strands of DNA are bound together, forming a double-helix The strands are complementary to each other, not identical. Watson and Crick first proposed this theory of a double helix.

35. DNA Structure • Compare a purine to a pyrimidine. • Why does Adenine bond with Thymine and not with Cytosine? • Weak hydrogen bonds hold the DNA helix together. What is the importance of using weak bonds? • If 15% of the nucleotides in DNA are cytosine, what percentage of the nucleotides are adenine? Why? • What types of bonds exist in DNA and where do they work?

36. DNA Replication

37. DNA Replication Chromosomes are long strands of DNA that must be duplicated before cell division. Complementary strands of the double helix must separate before replication occurs.

38. Leading Strand Lagging Strands

39. DNA Replication These strands divide by breaking the weak hydrogen bonds between the nucleotides. DNA Helicase is the enzyme that breaks the hydrogen bonds between the nitrogen bases. -The area where the helix splits is called the replication fork.

40. DNA Replication

41. DNA Replication Free-floating nucleotides bind to the newly uncovered nucleotide sequences. DNA Polymerase is an enzyme that adds the new nucleotides. DNA Polymerase works in opposite directions on the separated DNA strand.

43. DNA Replication The double helix unzips entirely and forms two identical double helix. These two helices are each made of one original strand and one new strand. (Semi-Conservative Replication)

45. Replication • What makes DNA replication semi-conservative? • Compare DNA Helicase to DNA Polymerase. • How do the DNA polymerases travel on the DNA strands? • How is eukaryotic DNA replicated so quickly? • Compare the Leading and Lagging Strands.

46. 3 4 2 1

47. Protein Synthesis

48. Protein Synthesis Directions of DNA DNA follows a specific path to produce proteins. RNA is used as an intermediate to proteins. DNA > Transcription > RNA > Translation > Protein

49. Protein Synthesis RNA vs. DNA RNA has one strand… DNA has two strands RNA uses Ribose sugar….DNA uses Deoxyribose. Uracil replaces Thymine in RNA RNA strands are very short, and DNA strands are very long.