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CHAPTER 12:

CHAPTER 12:. DNA and RNA. Review. What organelle is known as the “control center” of the cell? What structures are found in the nucleus? What are located on chromosomes? What are chromosomes composed of? How do genes and chromosomes control the activity of the cell?. Griffith Experiment.

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CHAPTER 12:

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  1. CHAPTER 12: DNA and RNA

  2. Review • What organelle is known as the “control center” of the cell? • What structures are found in the nucleus? • What are located on chromosomes? • What are chromosomes composed of? • How do genes and chromosomes control the activity of the cell?

  3. Griffith Experiment

  4. Figure 12–2 Griffith’s Experiment Section 12-1 Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Harmless bacteria (rough colonies) Control(no growth) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies)

  5. Figure 12–2 Griffith’s Experiment Section 12-1 Heat-killed, disease-causing bacteria (smooth colonies) Harmless bacteria (rough colonies) Harmless bacteria (rough colonies) Control(no growth) Heat-killed, disease-causing bacteria (smooth colonies) Disease-causing bacteria (smooth colonies) Dies of pneumonia Dies of pneumonia Lives Lives Live, disease-causingbacteria (smooth colonies) Transforming factor altered the Rough (harmless) Bacteria into Smooth (harmful) Bacteria

  6. Avery, MacCleod, and McCardy Experiment

  7. Avery, MacLeod and others • Did the same experiment as Griffith except with isolating the biological compounds of Carbohydrates, Lipids, Proteins and DNA to see which when missing did not allow the transformation • Only DNA was necessary for the transformation to occur; therefore it is the transforming factor.

  8. Hershey and Chase Experiment

  9. Figure 12–4 Hershey-Chase Experiment Section 12-1 Bacteriophage with phosphorus-32 in DNA Phage infectsbacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infectsbacterium No radioactivity inside bacterium

  10. Figure 12–4 Hershey-Chase Experiment Section 12-1 Bacteriophage with phosphorus-32 in DNA Phage infectsbacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infectsbacterium No radioactivity inside bacterium

  11. Figure 12–4 Hershey-Chase Experiment Section 12-1 Bacteriophage with phosphorus-32 in DNA Phage infectsbacterium Radioactivity inside bacterium Bacteriophage with sulfur-35 in protein coat Phage infectsbacterium No radioactivity inside bacterium Validated that DNA is the agent of genes

  12. Chargaff Rule

  13. Percentage of Bases in Four Organisms Section 12-1 Source of DNA A T G C Streptococcus 29.8 31.6 20.5 18.0 Yeast 31.3 32.9 18.7 17.1 Herring 27.8 27.5 22.2 22.6 Human 30.9 29.4 19.9 19.8

  14. Rosalind Franklin and Maurice Wilkins

  15. But we must not forget Rosalind Franklin

  16. Watson and Crick

  17. Watson & Crick http://www.ted.com/index.php/talks/james_watson_on_how_he_discovered_dna.html

  18. A passion to KNOW "You've got to be in it because you are actually curious about something. That's the fundamental. You can't go into science to be famous. You go into science because you are curious. That has to be the driving force." --Watson

  19. Evidence of DNA Structure • X-Ray Diffraction • Rosalind Franklin and Maurice Wilkins • Chargaff base pairing • A- • G- • Watson and Crick Final DNA model • Double • Nobel Prize winners in 1962 T C Helix

  20. Summary

  21. Building block of DNA • _____________ are the building block • Consist of: • 5-Carbon sugar (Deoxyribose), • Phosphate group, and • Nitrogenous base: • Adenine and Guanine : _____________ • Thymine and Cytosine: _____________ • Sugar and Phosphate groups form __________ while nitrogenous bases ______________ in between. Nucleotides Purines Pyrimidines backbone hydrogen bond

  22. Figure 12–5 DNA Nucleotides Section 12-1 Purines Pyrimidines Adenine Guanine Cytosine Thymine Phosphate group Deoxyribose

  23. Figure 12–7 Structure of DNA Section 12-1 Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

  24. Summary of DNA structure

  25. I Q #2 • What is the genetic code? Why is it important? • What was Frederick Griffith studying originally? • Define Transformation • Avery, and colleagues discovered that DNA is the _______________. • Hershey and Chase worked with __________. • What is the building block of DNA? What is it composed of?

  26. 12-2: Chromosomes and DNA Replication lack nuclei • DNA and Chromosomes a. Prokaryotes ___________and their DNA is found in the cytoplasm. b. It consists of a _____________________ DNA molecule c. This is the cells ______________ d. Eukaryotic DNA is more complicated e. It is not free in the cytoplasm but is contained in the _________ of the cell. f. It forms a _______ of chromosomes not just one g. humans have __, Drosophila have __ and a Sequoia tree have __. large, singular circular chromosome nucleus number 8 46 22

  27. 1. DNA Length a. ____ molecules are surprisingly long b. prokaryotes DNA of E. coli is over __ million base pairs long. c. it must be ___________________ that is one-one thousandths it’s size. (see fig. 12-9) d. How does it do this? DNA 4 packed into a space

  28. eukaryotic cells 2. Chromosome Structure a. DNA in ______________ is even more tightly packed. b. Eukaryotic DNA has over _______ DNA base pairs and is measured at over 1 meter of DNA c. It is folded into a tiny _____________ d. How does it do this? e. Eukaryotic DNA contains both DNA and ________(proteins) packed together to form _________. 6 billion chromosome histones chromatin

  29. DNA 2. Chromosome Structure (cont.) f. Chromatin consists of ____ tightly wrapped around histones to form a _________ structure called a ___________. g. Nucleosomes pack with one another to form a thick fiber and are _________ by a system of ______________. h. During the _________ these fibers are dispersed and __________. i. During _________ they are condensed and coiled into the ________ chromosomes. j. What do nucleosomes do? _____________ _______________________________________ _______ beadlike nucleosome shortened loops and coils cell cycle not visible mitosis visible they are able to fold the DNA into the tiny space of the cell nucleus

  30. Nucleosome Chromosome DNA double helix Coils Supercoils Histones DNA Supercoiling into Chromosomes

  31. Genetic code • DNA Replication Remember what Watson and Crick learned about DNA: - Holds the in the sequence of nucleotides • Is - consists of two parallel strands of sugar-phosphate groups. Pairs of nitrogenous bases link the two strands together, forming a • The Nitrogen (N)-base pairing is because each strand can be used to make the other strand. double stranded double helix complementary

  32. prokaryotes continues in two directions • DNA Replication • In ____________ replication begins on one point on the chromosome and ___________ ______________ • In __________ the DNA replication occurs in ________ of places and occurs in ____ _____________ until each chromosome is copied. • The sites where separation and replication occur are called _______________. eukaryotes both directions hundreds replication forks

  33. The Structure of DNA = Phosphate = Deoxyribose (5-c sugar) = N-base (A-T) (G-C) Hydrogen bonds

  34. The Replication of DNA Try your own: A A T T T C G A T G G C (Strand 1) (Strand 2) A. This aids in DNA replication. T T A A A G C T A C C G Each strand of the double helix serves as a template, or model, for the new strand

  35. The Replication of DNA When a cell divides to form new cells, the DNA must REPLICATE to ensure new cells have a new copy. B. Q: Why does DNA need to replicate? A: C. DNA replication (aka: DNA synthesis) is done with the aid of . Enzymes (DNA Polymerase)

  36. The Replication of DNA Separate or “unzip” the two strands of the double helix. D. The Enzymes: 2. 3. 4. Insert the appropriate bases. Covalently bond the sugar to the phosphate Proofread the bases to make sure they were paired correctly

  37. Interactive DNA ReplicationA Science Odyssey: You Try It: DNA Workshop Activity

  38. Original strand DNA polymerase New strand Growth DNA polymerase Growth Replication fork Replication fork Nitrogenous bases New strand Original strand DNA Replication

  39. The Replication of DNA (Summary) The Hydrogen Bonds (between N-bases) break and “unzips” the DNA • The steps in DNA replication 1. 2. Each strand serves as a template for the attachment of complementary bases

  40. The Replication of DNA Base Pairing 2 New Strands Unzip http://www.abbysenior.com/biology/dna_protein_synthesis.htm

  41. 12-3 RNA and Protein Synthesis proteins Proteins are made outside the nucleus on ribosomes • DNA holds the genetic code to make • DNA • How does DNA get the code outside the nucleus? A: Cannot leave the nucleus RNA(Ribonucleic Acid) acts as a messenger between DNA and the ribosomes and carries out the process by which proteins are made from Amino Acids. DNA mRNA Protein

  42. mRNA and DNA interaction Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNApolymerase DNA RNA

  43. I. The Structure of RNA A. Similar to DNA with a few differences: Single Stranded (can form double strand if it folds back on itself). Double Stranded Deoxyribose Ribose A-U G-C A-T G-C

  44. The Structure of RNA B. 3 types of RNA: • mRNA (messenger RNA) 2. tRNA (transfer RNA) • rRNA (ribosomal RNA) Copies the code off DNA in the nucleus and brings it out of the nucleusto the ribosomes Carries amino acids to the ribosomes Along with proteins, rRNA makes the subunits of the ribosomes

  45. Different Forms of RNA 50S 30S

  46. II. Transcription: RNA Synthesis The process by which a molecule of DNA is copied to a complementary strand of RNA A. Transcription= Page 147

  47. Transcription: RNA Synthesis RNA polymerase (enzyme) attaches to a sequence of DNA known as the Promotor and separates the 2 strands B. Steps of Transcription: Step #1: Step #2: RNA nucleotides base pair with complementary DNA nucleotides with the help of RNA polymerase A T C G U A G C

  48. Transcription: RNA Synthesis Now try your own: DNA= T T T A G A G A C C G T A T C mRNA= A A A U C U C U G G C A U A G **Remember, RNA does not have Thymine!

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