1 / 39

Chapter 6

Chapter 6. Expression of Biological Information. Concepts review. Expression of Biological Information. DNA & Genetic Information. Operon. Abilities of DNA. Produce polypeptide. Forming new DNA. Gene hypothesis. DNA as genetic material. Protein synthesis. Griffith (1931).

gil
Download Presentation

Chapter 6

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 6 Expression of Biological Information

  2. Concepts review

  3. Expression of Biological Information DNA & Genetic Information Operon Abilities of DNA Produce polypeptide Forming new DNA Gene hypothesis DNA as genetic material Protein synthesis Griffith (1931) Beadle & Tatum (1944) Replication Avery et. al (1944) Hershey & Chase

  4. At the end of the lesson, you should be able to : • Explain DNA as the carrier of genetic information. • Explain gene concept : One gene one polypeptide • Describe the semi-conservative replication of DNA

  5. DNA as genetic material Carrier of genetic information

  6. DNA as genetic material… Frederick Griffith (1931) Streptococcus pneumoniae mouse Two types Mutant type Rough, non-virulent (IIR) Wild type smooth, virulent (IIIS)

  7. DNA as genetic material… Frederick Griffith (1931) Sample 1

  8. DNA as genetic material… Frederick Griffith (1931) Sample 2

  9. DNA as genetic material… Frederick Griffith (1931) Sample 3

  10. DNA as genetic material… Frederick Griffith (1931) Sample 4 Living S cells found in the blood

  11. DNA as genetic material… Frederick Griffith (1931) conclusion • Living R cells are converted to S cells. • Transformation occurred. What is the transforming agent?

  12. DNA as genetic material… Concepts of transformation • Transformation is a types of genetic transfer found in bacteria. • Bacteria can take up the externally DNA.

  13. DNA as genetic material… DNA as transforming agent Oswald T. Avery Colin MacLeod Maclyn McCarty

  14. DNA as genetic material… DNA as transforming agent S strain (killed) R strain (living) + centrifugation protease RNase DNase Protein destroyed RNA destroyed DNA destroyed Lipid eliminated Living S cells Living S cells Living R cells Living S cells No transformation

  15. DNA as genetic material… Avery et. al (1944) conclusion • The strain without DNA caused no transformation occur. • So, the transformation agent is DNA!

  16. DNA as genetic material… Hershey and Chase • Prove that DNA is the molecules that responsible as genetic information, not protein. Bacteriophages

  17. Gene Hypothesis One gene one polypeptide

  18. Gene Hypothesis… Edward Tatum George Beadle

  19. Gene Hypothesis… • George Beadle and Edward Tatum experiment: connection between genes & metabolism. • Neurospora crassa as experimental organism. • - short life-cycle, easily grown. • Since it is haploid for much of its life cycle, mutations would be immediately expressed.

  20. Gene Hypothesis… • Neurospora crassa able to synthesize all of the amino acids and other chemicals needed for growth • Mutations will affect a single genes and single enzymes in specific metabolic pathways.

  21. Gene Hypothesis… Beadle & Tatum Experiment

  22. Gene Case 1 Case2 Case 3 Amino acid Enzyme Amino acid Wild type neurospora Mutant neurospora Minimal Nutrient Minimal Nutrient

  23. How to make sure ONE genes is only code ONE polypeptide??? Is the gene B only produce enzyme B only? Is the gene C only produce enzyme C only? Is the gene A only produce enzyme A only? Gene A Gene B Gene C Precursor X X Enzyme A + Ornithine Ornithine X X Enzyme B + Citrulline Citrulline X X Enzyme C Arginine + Arginine

  24. Gene Hypothesis… Beadle & Tatum Experiment conclusion • Each gene will produce certain enzyme (polypeptide) • One gene one polypeptide.

  25. DNA Replication Model Meselson and Stahl

  26. DNA Replication Model… Proposed by Matthew Meselson (left) and Franklin W. Stahl (right) in 1958.

  27. DNA Replication Model… DNA Replication Process of copying a double stranded DNA strand which is the two resulting double strands are identical and each of them consist of one original and one newly synthesize strand.

  28. DNA Replication Model… • Watson and Crick suggest that each strands of DNA molecule could serve as template for the synthesis of opposite strand. • Each half-helix could pair with their complementary nucleotides to replace its missing partner. • Will result two DNA double helices, each identical to the original.

  29. DNA Replication Model… Meselson & Stahl (1958) Studied the replication in E. coli 3 hypotheses conservative semiconservative dispersive Which one is the model of DNA replication?

  30. DNA Replication Model… Meselson & Stahl (1958) Hypothesis 1 conservative Both parent strand remain together and all new copies is made.

  31. DNA Replication Model… Meselson & Stahl (1958) Hypothesis 2 semiconservative The 2 strand of the parental molecule separate and each functions as a template for synthesis of a new complementary strand

  32. DNA Replication Model… Meselson & Stahl (1958) Hypothesis 3 dispersive • Each strand of both daughter molecules contains a mixture • of old and newly synthesized parts

  33. DNA Replication Model… Meselson & Stahl (1958)

  34. DNA Replication Model… Meselson & Stahl (1958) Result First replication Second replication

  35. DNA Replication Model… Meselson & Stahl (1958) Result First replication Second replication

  36. DNA Replication Model… Meselson & Stahl (1958) Result First replication Second replication

  37. DNA Replication Model… Meselson & Stahl (1958) First replication Second replication

  38. DNA Replication Model… Meselson & Stahl (1958) conclusion DNA replication is take place by semiconservative.

More Related