Bio 99 Midterm 1 Lec 2

  1. Griffith (1928)
    (trying to see if DNA is the genetic material)
    principles (2)
    • bacterial transformation
    • genetic recombination
  2. bacterial transformation
    genetic recombination by introduction of foreign DNA
  3. genetic recombination
    exchange of DNA between chromosomes
  4. Diplococcus pneumoniae
    wildtype: IIIS
    • virulent
    • smooth colonies
    • polysaccharide capsule
  5. Diplococcus pneumoniae
    mutant: IIR
    • non-virulent
    • rough colonies
    • no capsule
  6. Griffith's transformation experiment: encapsulated
    (define and outcome of injection into mouse)
    • smooth strain (virulent)
    • mouse dies
  7. Griffith's transformation experiment: non-encapsulated
    (define and outcome of injection into mouse)
    • rough strain (nonvirulent)
    • mouse lives
  8. Griffith's transformation experiment: heat-killed smooth strain
    (outcome of injection into mouse)
    mouse lives
  9. Griffith's transformation experiment: heat-killed smooth strain and rough straine
    (outcome of injection into mouse)
    mouse dies
  10. What is the hypothesis (explanation) for outcomes?
    genetic component transferred from Type IIIS to Type IIR
  11. Avery, Macleod, and McCarty (1944)
    critical methodologies (2)
    • selection (biological) for rare transformation
    • fractionation of cell-free extract to isolate single component
  12. Preparation of transforming principle from S strain (steps)
    • begin with encapsulated strains
    • 1. disrupt cells
    • 2. centrifuge
    • now we have cell-free extract
    • 1. precipitate with ethanol
    • 2. redissolve in water
    • now we have transforming principle from S strain
  13. Addition of transforming principle from S strain (steps)
    • transforming principle from S strain is added to test tube with R strain
    • mix and spread onto agar plates
    • a culture with both S and R cells form on plate
  14. inject smooth strain (virulent)
    mouse dies
  15. inject rough strain (nonvirulent)
    mouse lives
  16. inject heat killed smooth strain
    mouse lives
  17. inject heat-killed smooth strain and rough strain
    mouse dies
  18. inject DNA from heat-killed smooth strain and rough strain
    mouse dies
  19. treat with ribonuclease (RNAse)
    mouse dies
  20. treat with protease
    mouse dies
  21. treat with nuclease (DNAse)
    mouse lives
  22. Hershey and Chase (1952)
    "Blender Experiment"
    used bacteriophage T2 to determine whether protein or DNA encodes genetic information
  23. phage
    • protein head and tail with DNA molecules
    • inject DNA into bacteria
    • (proteins contain sulfer; DNA contains phosphates
  24. Explain Hershey and Chase "Blender Experiment"
    Testing Proteins
    • protein coats radiolabelled
    • bacteria infected 
    • no radioactivity enters cell
    • phage grown with radioactive sulfur (35S)
    • centrifuge
    • radioactivity in supernatant
    • conclusion: proteins are NOT the genetic material
  25. Explain Hershey and Chase "Blender Experiment"
    Testing DNA
    • phage DNA radiolabelled
    • bacteria infected
    • radioactivity enters cells
    • phage grown with radiactive phosphorus (32P)
    • centrifuge
    • radioactivity in pellet
    • conclusion: DNA is the genetic material
  26. minimal media
    those that contain the minimum nutrients possible for organism growth, generally without the presence of amino acids, and are often used to grow "wild type" organisms
  27. auxotrop
    an organism unable to synthesize a particular organic compound (ex. amino acid) for its growth
  28. selective media
    used for selection of certain cells able to survive in selective media
  29. Provide 2 examples of the use of minimal media
    • minimal medium lacking amino acids (thus lacking arginine) will select against N.crassa unable to synthesize it, and will select for "wild type" cells able to synthesize it
    • if an organism is resistant to a certain antibiotic (such as neomycin), then that antibiotic can be added to the medium in order to prevent other cells, which do not possess the resistance, from growing
  30. Arg1
    gene involved in Arginine synthesis
  31. knock out Arg1
    grow on minimal media
    no growth?
  32. knock out Arg1
    grow on minimal media supplemented with arginine
  33. knock out Arg1
    grow on minimal media supplemented with ornithine
    no growth?
  34. neomycin resistance gene encodes for....
    neomycin blocks.....
    • protein capable of modifying neomycin antibiotic, blocking its activity
    • protein synthesis
  35. NeoR: Neomycin Resistance Gene
    confers resistance to antibiotic Neomycin
  36. Introduct NeoR
    Grow on minimal media with Neomycin
  37. Introduce NeoR
    Grow on minimal media
    no growth?
  38. You decide to knock out Arg1 using NeoR as a selection marker. What type of media will you plate your N. crassa on to obtain the arg1 KO strain?

  39. splicing (introns and exons)
    • introns get spliced out because they remain in the nucleus
    • exons stay in the mRNA strand because they leave the nucleus
  40. the sequences that constitute an organism
    • chromosomal
    • could be DNA or RNA
    • contains protein/RNA coding sequences as well as non-coding sequences
  41. genome
    the haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular organism
  42. gene
    a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring
  43. From sequencing countless genomes,we know in general that more complex organisms have:
    1. larger genomes 2. more genes

  44. Which of the following is not a conclusion that can be made from the Human Genome Project?

  45. What’s the value of having genomic sequences?
    • •Identifying gene function through homology
    • •Being able to manipulate a gene by site directed mutation
    • •Allows us to identify the closeness of the relationship between different organisms
    • •Provides information on the genetic basis of diseases
  46. Value of Mobile DNA
    • •Can regulate gene expression
    • •Can result in gene duplications
    • •Can generate mutations – mobile DNA was key for the evolution of more complex organisms
    • •Used in the lab to manipulate genomes
Card Set
Bio 99 Midterm 1 Lec 2