Chapter 10 notes


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Chapter 10 notes

  1. 1. DNA, RNA, and Protein Synthesis Chapter 10
  2. 2. Section 1DISCOVERY OF DNA
  3. 3. Griffith’s Experiments• Fredrick Griffith studied bacteria that cause pneumonia – Some strains, or types, were harmful and caused pneumonia in mammals (smooth) – Other strains were harmless and did not cause pneumonia (rough)
  4. 4. Griffith’s Experiments• Used the two strains of bacteria in four experiments• Discovered that genetic material can be transferred from one cell to another and change those cells• He called this transformation
  5. 5. Griffith’s Experiments
  6. 6. Avery’s Experiments• Oswald Avery wanted to find out what factor caused the transformation in Griffith’s experiments• Discovered that the factor was DNA
  7. 7. Hershey-Chase Experiment• Experimented with bacteriophages – viruses that infect bacteria• Confirmed that DNA is the hereditary molecule
  8. 8. Hershey-Chase Experiment
  9. 9. Section 2DNA STRUCTURE
  10. 10. DNA Double Helix• Structure of DNA discovered in 1953 by James Watson and Francis Crick• Used Maurice Wilkins and Rosalind Franklin’s x-ray picture of DNA to help
  11. 11. DNA Nucleotides• Made of two long strands of nucleotides – Each nucleotide contains three parts • Five-carbon sugar (deoxyribose) • Phosphate group • Nitrogenous base
  12. 12. DNA Nucleotides
  13. 13. Bonds Hold DNA Together• Structure is similar to a spiral staircase – Alternating sugar and phosphate molecules = side handrails of the staircase – Base pairs = steps of the staircase
  14. 14. Nitrogenous Bases• Four kinds of bases – Adenine – Guanine – Thymine – Cytosine
  15. 15. Complementary Bases• Base-pairing rules:• cytosine always pairs with guanine• adenine always pairs with thymine
  16. 16. Complementary Bases• What is the complementary sequence of bases for the following strand of DNA?• ACCTGTGAGAC• TGGACACTCTG
  17. 17. Section 3DNA REPLICATION
  18. 18. DNA Replication• DNA replication is the process by which DNA is copied in a cell before a cell divides
  19. 19. Steps of DNA Replication1. Enzymes called helicases separate the DNA strands
  20. 20. Steps of DNA Replication2. Enzymes called DNA polymerases add complementary nucleotides to each of the original strands
  21. 21. Steps of DNA Replication3. DNA polymerases finish replicating the DNA and fall off – Result is two separate and identical DNA molecules
  22. 22. DNA Errors in Replication• DNA replication is usually very accurate – Only about one error occurs for every billion nucleotides• When mistakes occur, a change in the nucleotide sequence results in a mutation
  23. 23. Section 4PROTEIN SYNTHESIS
  24. 24. Flow of Genetic Information• DNA RNA protein
  25. 25. RNA Structure and Function• RNA is very similar to DNA – long strand of nucleotides
  26. 26. RNA Structure and Function• RNA is different from DNA in the following ways: – Contains the sugar ribose instead of deoxyribose – Contains uracil instead of thymine – Single-stranded – Much shorter than DNA
  27. 27. Types of RNA• There are three major types of RNA that each play a different role in protein synthesis
  28. 28. Types of RNA• Ribosomal RNA (rRNA) – makes up part of the ribosome
  29. 29. Types of RNA• Messenger RNA (mRNA) – carries the message from DNA in the nucleus to the ribosomes in the cytoplasm
  30. 30. Types of RNA• Transfer RNA (tRNA) – transfers amino acids to the ribosome to make a protein
  31. 31. The Genetic Code• The genetic code is the rules for how a sequence of bases codes for a particular amino acid• Each group of three nucleotides is called a codon and codes for an amino acid
  32. 32. The Genetic Code
  33. 33. Transcription• Instructions for a gene coded in DNA are rewritten into an RNA molecule
  34. 34. Translation• Translation = the making of a protein
  35. 35. Steps of Translation1. mRNA is fed through a ribosome three bases at a time
  36. 36. Steps of Translation2. Molecules of tRNA translate the mRNA code by picking up a specific amino acid from the cytoplasm
  37. 37. Steps of Translation3. In the ribosome, bases on the tRNA match with bases on the mRNA like pieces of a puzzle
  38. 38. Steps of Translation4. tRNA releases their amino acids and they become linked in a chain