DNA, RNA, and Protein Synthesis

1. DNA, RNA, and Protein Synthesis Chapter 12 and 13 chap 12 notes

2. Chap 12 Terms • Transformation • Bacteriophage • Base pairing • Nucleotides • Nucleic acids • Nitrogenous bases • Antparallel strands • Replication • Replication fork • DNA Polymerase • Helicase • Telomease • Ligase • Semi conservative

3. Do you know? • What determines how a protein will function? three-dimensional shape of the protein • Why is it important that new cells have same DNA as the parent cell? the cells may develop properties that would not be beneficial to the organism as a whole chap 12 notes

4. Objectives?? • Relate how Griffith’s bacterial experiments showed that a hereditary factor was involved in transformation • Summarize how Avery’s experiments led his group to conclude that DNA is responsible for transformation in bacteria • Describe how Hershey and Chase’s experiments led to the conclusion that DNA, not protein, is the hereditary molecules in viruses chap 12 notes

5. Discovery of DNA • From his studies with pea plants, Mendel concluded that hereditary factors determine many of an organism’s traits. But what were these hereditary factors? How did these molecules store hereditary information? Scientists believed that if they could answer these questions, they could und4erstand how cell pass on characteristics to their descendants. The answers these questions began to emerge during an epidemic of pneumonia in London in the 1920s. chap 12 notes

6. Experiments • Three experiments that led to the discovery of DNA and RNA 1. Griffith’s 2. Avery’s 3. Hershey-Chase experiments Studies involved bacteria (bacteriophages or phages) and viruses (DNA head, protein body) chap 12 notes

7. Griffith’s experiments • 1928- studied bacteria Streptococcus pneumoniae (pneumonia) • Trying to develop a vaccine against virulent strain (disease-causing) • Virulent bacterium is surrounded by a capsule made of polysaccharides that protect it from a body's defense systems chap 12 notes

8. Griffiths exp cont Two strains of bacteria 1. S strain – smooth-edged colonies, ill 2. R stain- rough colonies, lacks a capsule, does not cause pneumonia • Had a series of 4 exp fig 10-2 (BIO) • R cells  mouse alive • S cells  mouse dies • Kills S cells with heat  mouse lives • Kills S cells with heat and mix with R cells mouse dies (transformation occurs) chap 12 notes

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10. Griffiths exp cont • Results or conclusion: Heat-killed virulent bacterial cells release a hereditary factor that transfers the disease- causing the healthy cells to be harmful The transfer of genetic material from one cell to another is called transformation (holt video) chap 12 notes

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12. Heat Factor? • DNA can tolerate temperature near 90’C without being altered. Proteins are denatured (broken down) at about 60’C. • What effect temperature had on Griffith’s works? A: The DNA was not altered and became incorporated into the DNA of the living bacteria chap 12 notes

13. DNA Technology • Griffith manipulated genes with out knowing it. Today this manipulation of genes is known as genetic engineering or recombinant DNA Technology. • Transformation is a modern-day genetic engineering technique. • Examples: bacteria used to introduce foreign genes into plant cells, producing plants with desirable traits (Genetic modified) chap 12 notes

14. Avery's Experiments • 1940’s wanted to test whether the transforming agent in Griffiths exp was protein, RNA, DNA • Used enzymes separately to id which part Results • Cells missing protein and RNA able to transform R cells into s cells  mice die • Cells missing DNA did not transform mice lived • DNA is responsible for transformation in bacteria chap 12 notes

15. Radioactivity review? • Radioactive elements have unstable nuclei that emit alpha and beta particles or energy as gamma rays. • Emissions make it easier for scientists to detect and trace the path of the radioactive elements as they interact with other materials or transformed during metabolic processes • (Radioactive isotopes, increase # neutrons, and the mass of the element) chap 12 notes

16. Hershey-Chase Experiment ?They wanted to know if DNA or Protein was the hereditary material viruses transfer when viruses enter a bacterium • Bacteriophages or phages are viruses that infect bacteria (Holt video) EXP: • Used radioactive isotope sulfur (35S) to label protein and radioactive isotope phosphorus (32P)to label DNA • Infected the cells • Blended separated the phage from bacteria Results: Viral DNA and little protein entered bacteria  concluded that DNA is the hereditary molecule in the viruses (Honors 10.A) chap 12 notes

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20. Key Questions: • Evaluate the contributions of Franklin and Wilkins in helping Watson and crick discover DNA’s double helix structures • Describe the 3 parts of a nucleotide • Summarize the role of covalent and hydrogen bonds in the structure of DNA • Relate the role of the base-paring rules to the structure of DNA chap 12 notes

21. DNA • By the early 1950s, most biologist accepted DNA as the hereditary material. However, they still lacked an understanding of DNA’s structure or how this molecule could replicate, store, and transmit hereditary information and direct cell function. These mysteries would soon begin to unravel at Cambridge university in England. chap 12 notes

22. DNA is a double-stranded Helix • Pauling, Wilkins, Franklin- were first • They used x-ray diffraction • Watson saw an x-ray produced by Franklin and was able to figure out the basic shape of DNA to be a helix (fig 10-5 bio) • Watson and Crick began trying to construct a double helix w/ uniform diameter that would confirm Franklins data • 1962 W and C received the Nobel Prize in Medicine and Franklin died in 1958 never to receive the award – currently recognized at Cambridge chap 12 notes

23. http://www.accessexcellence.org/RC/AB/BC/Rosalind_Franklin.phphttp://www.accessexcellence.org/RC/AB/BC/Rosalind_Franklin.php http://www.blinkx.com/video/rosalind-franklin-dna-discoveries-in-science-and-art/A3fUh_J7RZ77E7Njdd7zcA chap 12 notes

24. DNA Nucleotides • DNA is a nucleic acid made of two long chains of Polymers made of monomers which is made of nucleotides • Nucleotide is made of 3 parts 1. 5-carbon sugar (deoxyribose) 2. Phosphate group 3. Nitrogenous base chap 12 notes

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27. Bonds hold DNA together • DNA looks like a spiral staircase • Covalent bonds and hydrogen bonds Nitrogenous bases: 4 types: a. Purines- contain double ring of carbon 1. Adenine 2. Guanine b. Pyrimidines- have a single ring of carbon 3. Thymine 4. Cytosine chap 12 notes

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29. Complementary Bases • 1949- Chargaff observed percentages of A= T, C= G • Base-paring rules- single strand pairs up with second strand to make a double strand • Complementary base pairs- A= T, C= G • Base sequence- order of nitrogenous bases on a chain chap 12 notes

30. DNA model • Looks like a ladder • Sugar-phosphate is the handrails • Base pairs are steps • Draw in the complementary base pairs to: AACCTGACTGGACAC chap 12 notes

31. DNA replication Key Questions • Summarize the process of DNA replication • Identify the role of enzyme in the replication of DNA • Describe how complementary base paring guides DNA replication • Compare the number of replication forks in prokaryotic and eukaryotic cells during DNA replication • Describe how errors are corrected during DNA replication chap 12 notes

32. Q and A Q: Why do you think gives DNA its stability even though the hydrogen bonds between the nitrogenous bases are easily broken?. A: Strong covalent bonds connect the sugar and phosphate groups of the DNA backbone chap 12 notes

33. DNA Replication • Watson and Crick’s discovery of the double helix structure of DNA caused great excitement in the scientific community. Scientists realized that this model could explain simply and elegantly how DNA can replicate exactly each time a cell divides, this is a key feature of hereditary material. chap 12 notes

34. How DNA Replication occurs • Process by which DNA is copied in a cell before a cell divides by mitosis, meiosis, or binary fission • The two nucleotide strands of the original double helix separate along the strands • Strands become templates to make new complementary strands • Two identical DNA (double helix) separate and move to new cell during division chap 12 notes

35. Steps of replication • Helicases- enzyme that separate the DNA strands, move along the molecule breaking the H-Bond between the complementary nitrogenous bases, a Y-shaped region is formed called the replication fork • DNA polymerase adds complementary nucleotides • DNA poly completes strand and falls off • DNA ligase links the pieces together • Get two identical DNA molecules This is called a semi-conservative replication- keeps one of the original (conserved) chap 12 notes

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41. Prokaryotic DNA Replication • In most prokaryotes, DNA replication does not start until regulatory proteins bind to a single starting point on the chromosome. This triggers the beginning of DNA replication. • Replication in most prokaryotic cells starts from a single point and proceeds in two directions until the entire chromosome is copied.

42. Eukaryotic DNA Replication • Eukaryotic chromosomes are generally much bigger than those of prokaryotes. • In eukaryotic cells, replication may begin at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is completely copied.

43. Chapter 13 Key Terms • RNA • mRNA • rRNA • tRNA • Transcription • Translation • RNA Polymerase • Genetic code • Translation • Anticodon • Condon • Polypeptide • Gene expression • Mutations • Point mutation • Fram shift • mutatgens

44. Characteristics such as hair color are largely determined by genetic factors. But how does inheriting a particular form of a gene result in the appearance of a specific hair color? The structure of DNA helps explain how genes function in making proteins that determine traits in an organism. Protein Synthesis chap 12 notes

45. Misconception • Different cells, same DNA You might think that because cells in the same organism appear different and have different functions, the cells must have different DNA. The first fertilized egg undergoes DNA replication and then mitosis and then repeated to give every cell in the body the same DNA. (except for when crossing over takes place during meiosis to create gametes) ** other factors determine which genes are used for the cell’s specific function chap 12 notes

46. Key Questions • Outline the flow of genetic information in cells from DNA to protein • Compare the structure of RNA To DNA • Summarize the process of transcription • Describe the importance of the genetic code • Compare the role of mRNA, rRNA, tRNA in translation • Id the importance of learning about the human genome chap 12 notes

47. Flow of genetic info • Gene- segment of DNA that is located on a chromosome and codes for a specific trait Process in Eukaryotic cells DNA  transcription RNA translation  protein • Transcription- DNA acts as a template for the syn of RNA chap 12 notes

48. Flow of genetic info cont 2. translation- RNA directs the assembly of proteins 3. Protein synthesis- proteins are formed based on information in DNA and carried out by RNA (gene expression) DNA (double stranded) RNA (single) Protein * Proteins are responsible for protecting the body against infections and carrying oxygen in red blood cells chap 12 notes

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50. RNA Structure and Function • RNA is a nucleic acid made up of nucleotides 4 major differences from DNA 1. contain the sugar ribose not deoxyribose 2. contains the nitrogenous base uracil not thymine 3. single stranded not double 4. usually much shorter in length chap 12 notes