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DNA / Protein Synthesis

DNA / Protein Synthesis. History of DNA Research. DNA – Deoxyribonucleic acid 1) Frederick Griffith (1928)- discovered that a factor in heat-killed, disease-causing bacteria can “transform” harmless bacteria into ones that can cause disease. Griffith's Experiments

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DNA / Protein Synthesis

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  1. DNA / Protein Synthesis

  2. History of DNA Research DNA – Deoxyribonucleic acid 1) Frederick Griffith (1928)- discovered that a factor in heat-killed, disease-causing bacteria can “transform” harmless bacteria into ones that can cause disease.

  3. Griffith's Experiments • Griffith set up four individual experiments. • Experiment 1: Mice were injected with the disease-causing strain of bacteria. The mice developed pneumonia and died.

  4. Harmless bacteria (rough colonies) • Experiment 2: Mice were injected with the harmless strain of bacteria. These mice didn’t get sick. Lives

  5. Experiment 3: Griffith heated the disease-causing bacteria. He then injected the heat-killed bacteria into the mice. The mice survived. Heat-killed disease-causing bacteria (smooth colonies) Lives

  6. Heat-killed disease-causing bacteria (smooth colonies) • Experiment 4: Griffith mixed his heat-killed, disease-causing bacteria with live, harmless bacteria and injected the mixture into the mice. The mice developed pneumonia and died. Harmless bacteria (rough colonies) Live disease-causing bacteria(smooth colonies) Dies of pneumonia

  7. Heat-killed disease-causing bacteria (smooth colonies) • Griffith concluded that the heat-killed bacteria passed their disease-causing ability to the harmless strain. Harmless bacteria (rough colonies) Live disease-causing bacteria(smooth colonies) Dies of pneumonia

  8. Transformation  • Griffith called this process transformation because one strain of bacteria (the harmless strain) had changed permanently into another (the disease-causing strain). • Griffith hypothesized that a factor must contain information that could change harmless bacteria into disease-causing ones.

  9. History of DNA Research 2) Oswald Avery (1944)- discovered DNA was responsible for transformation

  10. History of DNA Research 3) Hershey and Chase (1952)- their studies supported Avery’s work by studying bacteriophage (a virus that infects bacteria)

  11. History of DNA Research 4) Watson and Crick (1953)- first to develop a double-helix model of DNA

  12. DNA • DNA is found inside the nucleus of every cell in your body

  13. DNA Structure • DNA is made up of nucleotides. Nitrogenous Base Phosphate Sugar

  14. Parts of a nucleotide • A nucleotide contains three parts: 1) Phosphate group 2) 5-carbon sugar group (deoxyribose) 3) Nitrogenous bases (4 types) • Adenine (A) • Guanine (G) Purines (double rings) • Cytosine (C) • Thymine (T) Pyrimidines (single ring) To help you remember: CUT = PY

  15. Chargaff’s Rule • Erwin Chargaff (1949) discovered the base-pairing rules for nitrogenous bases: 1) A always pairs with T C always pairs with G 2) % A in DNA = % T in DNA % C in DNA = % G in DNA

  16. Guanine Cytosine Adenine Thymine

  17. Double Helix • DNA molecule is composed of two long chains of nucleotides twisted and held together by hydrogen bonds in the center between the nitrogen bases

  18. DNA Double Helix

  19. In even in your smallest chromosome there are 30 million base pairs. How does so much DNA fit in every tiny cell in your body?

  20. DNA • You fold it! • Think about how much easier it is to pack your suitcase when everything is nicely folded. Can’t fit Much more fits when you organize and fold it.

  21. DNA must condense (make itself smaller) by folding itself around proteins called Histones. • When DNA wraps around Histones it forms tight coils and is called chromatin.

  22. What are histones? • Histones are proteins that DNA wraps around. • What is Chromatin? • Chromatin is what you call DNA when it is wrapped around the Histones.

  23. Example: Histone DNA Double Helix Chromatin DNA around histones

  24. Chromosomes • When the chromatin forms coils and condenses it forms a chromosome. • See Fig. 12-10 in your book.

  25. DNA Double Helix Chromosomes Made up of chromatin Chromatin DNA around histones Histone =

  26. DNA Double Helix  Chromatin  Chromosome DNA Double Helix DNA Chromatin DNA Chromosome http://www.biostudio.com/demo_freeman_dna_coiling.htm (dna coiling)

  27. DNA Replication • Occurs when cells divide. (Cell division)

  28. DNA Replication • DNA makes an exact copy of itself • takes place inside the nucleus during S phase before cell division

  29. Replication • Each strand of the double helix of DNA serves as a template against which the new strand is made.

  30. phosphate Sugar-phosphate Sugar-phosph DNA Base Pairing Rules • A compliments T • T compliments A • G compliments C • C compliments G G A C T T C A A G T

  31. Replication Step 1: The hydrogen bonds between the double helix break and two strands separate. Each strand is called a template strand. Step 2: Two new complementary strands are formed following the rules of base pairing. The new strands are called complimentary strands. Template strand Compliment strand

  32. DNA Polymerase A T How DNA Replication Works! DNA polymerase is an enzyme that adds the complimentary bases to the DNA template strand and also “proofreads” or checks that it is correct.

  33. Semiconservative

  34. Replication • Template Strand (original) • CGTATCCGGAATTT • The complimentary strand.. • GCATAGGCCTTAAA

  35. Template strand Complimentary Strand ACGGCAT TACGGCAT TGCCGTA ATGCCGTA

  36. Complimentary • If I have a strand that DNA sequence of CAT what would be on the complimentary strand? • CAT GTA

  37. RNA • Ribonucleic acid • Single strand • made up of nucleotides • contains three parts: • 1) Phosphate group • 2) 5-carbon sugar group (ribose) • 3) Nitrogenous bases (4 types) • Adenine (A) • Guanine (G) Purines (double rings) • Cytosine (C) • Uracil (U) Pyrimidines (single ring)

  38. Base-pairing in RNA 1) A always pairs with U 2) C always pairs with G

  39. Types of RNA

  40. Compare DNA and RNA 1) Sugars are different: DeoxyriboseRibose H OH OH OH H OH OH OH

  41. Compare DNA and RNA DNA RNA 2) A, G, C,T A, G, C, U (A–T, C-G) (A-U, C-G) 3) Double stranded Single stranded 4) only 1 type 3 types

  42. Protein • Proteins are made of building blocks called amino acids. • Proteins are different from one another by the sequence, or order, of their amino acids.

  43. Protein • There are 20 different amino acids. • Thousands of proteins can be made from these amino acids because there are many different orders that they can be in.

  44. Proteins are made in two steps: • Transcription • Translation

  45. What is transcription? • The process where mRNA is made from a DNA template • Transcription happens in the nucleus

  46. What is translation? • Translation is the decoding of an mRNA message into a protein. • Translation takes place on ribosomes in the cytoplasm

  47. Transcription Translation

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