Microbio Unit 6 Genetics

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tasha081
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40966
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Microbio Unit 6 Genetics
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2010-10-15 12:43:16
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genetics
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Genetics - Exam 2
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  1. Transcription
    copying
  2. DNA
    the code
  3. RNA
    • the copy
    • ribonucleic acid
  4. Protein
    • result of the code
    • the translation
    • DNA is transcribed into RNA and translated as protein
  5. Translation
    interpretation; DNA transcribed into RNA and translated as protein
  6. Replication
    mode by which copies of DNA are made
  7. Reverse Transcriptase
    • transcribing RNA into DNA
    • done by viruses
  8. Chromosome
    Independently replicating peice of DNA that is passed on to all daughter cells and encodes some genes that are essential for the survival of the cell
  9. Genome
    • Complete set of genes in a cell
    • Encodes all the genes necessary for a cell to survive
  10. Plasmid
    independently replicating piece of DNA passed on to all daughter cells but does not encode any genes essential for cell.
  11. Nucleotide
    • -basic unit of of DNA/RNA
    • -consists of a nitrogenous base, a phosphate, and a sugar
  12. Anti-parallel double helix
    One strand points in a 5' direction and the other in a 3' direction
  13. DNA Replication complex
    • -Helicase to unwind DNA
    • -Two DNA polymerases that replicate DNA in a 5' to 3' fashion
  14. Leading strand
    synthesized continuously 5' to 3'
  15. Lagging strand
    synthesized in short 5' to 3' fragments that are later ligated (glued together)
  16. Genetic
    -All the genes in the cell
  17. Gene
    • -DNA code that results in the making of a functional unit of RNA
    • -one specific unit of information
  18. RNA polymerase
    • -enzyme
    • -responsible for copying DNA into RNA
  19. DNA polymerase
    -enzyme
  20. mRNA
    • -Messenger RNA
    • -contains message translated into a protein
    • -in prokaryotes it is immediately translated into a protein
    • -in eukaryotes it must first be processed
  21. tRNA
    • Transfer RNA
    • transfers a specific amino acid to the ribosome where the protein is made; it recognizes the message in the mRNA by using a code
    • there is a tRNA for each amino acid and each tRNA recognized a spec code that represents that amino acid
  22. rRNA
    • ribosomal DNA
    • this DNA with ribosomal proteins froms the ribosome
  23. Ribosome
    Organelle that facilitates translation
  24. Genetic code
    code of DNA bases and amino acids
  25. Codon
    • 3 base code
    • 64 codons which code for 20 amino acids
    • 3 stop codons
  26. E site
    • ejection site
    • where tRNA no longer has an amino acid and is released back into cytoplasm
  27. P-site
    • peptide site
    • where tRNA is located that has peptide chain attached
  28. A site
    • active site
    • where the next tRNA comes in a decodes the mRNA
  29. Transpeptidation
    • second step in protein synthesis
    • the joining of one amino acid to another amino acid occurs via formation of a peptide bond
    • occurs when P site and A site are full
    • ribosome transfers the amino acid from the tRNA in the P site onto the amino acid that is on the tRNA in the A site
  30. Translocation
    • movement of the ribosome three bases (once codon) along mRNA
    • the tRNA that was in the Psite is now in the Esite
    • the tRNA that has the peptide attached that was in the Asite is now in the Psite
    • the A site is empty again
  31. Mutation
    • change in the nucleotide sequence of the genome of an organsim/virus
    • result in from the incorrect incorporation of a nucleotide into the genetic sequence
    • some will allow an organism to become resistant to antibiotics
  32. Induced Mutation
    result from exposure to known mutagens which are primarily physical or chemical agents thta interact with DNA/RNA in a disruptive manner
  33. Spontaneous Mutation
    random changes in DNA arising from mistakes in replication or the detrimental effects of a natural background radiation on DNA
  34. Recombination
    • process involving several dozen proteins
    • part of one sequence is inserted into another site with high sequence similarity
  35. Integration
    • site specific recombination with organisms genome
    • results in a double stranded DNA being inserted into the genome
  36. What does integration require?
    • 1) Integrase - enzyme which catalyzes double breaks
    • 2) Recognition sequence - must be present in both organsims DNA and invading DNA
    • 3) The invading DNA must encode the intergrase
  37. Integrase
    Enzyme
  38. Transposon
    • mobile genetic elements
    • able to integrate into an organisms genome and then later move to a new location in that genome
    • many are lysogenic phage
    • most move from one organism to another by piggybacking during txfer of DNA from one cell to another
  39. Transformation
    process by which cells can take up naked DNA from the environment
  40. Competent cells
    • cells that can be transformed
    • naturally competent: streptococcus, heliobacter, haemophilus, neissira
  41. Naturally competent
    take up DNA in their normal environment
  42. Conjugation
    self transmissable plasmids that direct the formation of a special pilus onthe surface of the bacterium
  43. Hfr strains
    High frequency of recombination
  44. Transduction
    transfer of genes from the donor cell to the recipient cell via a bacteriophage
  45. Restriction enzymes
    • counteract the ease of gene transfer resulting in the rejection of most foreign DNA
    • work by recognizing short sequences
  46. What does it mean that DNA is "semi conservative"
    each daughter cell receives a chromosome with one strand from the original parental chromosome, the opposite strand being a new copy of the original chromosome.
  47. DNA helicase
    a protein that unwinds helical DNA
  48. primase
    • binds to open DNA and makes a short RNA copy of the DNA that is called an RNA primer
    • essential b/c DNA polymerase can not start a DNA strand, it can only EXTEND a DNA strand
  49. DNA ligase
    enzyme which "glues" together fragments of information
  50. Topoisomerase
    enzyme which breaks open a circular chromosome to be re-linked
  51. Telomerase
    enzyme in eukaryotes which copies last bit of DNA such that the new chromosome are the same length as old chromosomes
  52. operons
    • transcriptional unit
    • may contain one or more different genes
  53. Activator
    • bind to DNA and help RNA polymerase to bind to DNA
    • often allow RNA polymerase to bind at sites where they normally wouldnt
  54. Regulon
    region containing the sequences that control gene expression
  55. Repressor
    bind to DNA and prevent RNA polymerase from binding to the DNA or from copying the DNA into RNA
  56. Missense mutation
    change that results in a different amino acid
  57. nonsense mutation
    mutation that results in the inserting of a stop codon
  58. frameshift
    • results in the insertion of deletion of nucleotides that change the reading frame of the mRNA
    • changes all amino acids from that point forward
  59. supressor mutation
    • mutations that result in a correction of the original mutation
    • may also result in a second mutation that compensates for the orig mutation without correcting it
  60. What is the central dogma of genetics?
    • DNA --------> RNA -------------> protein
    • transcripton translation
  61. What are the four levels of structure of chromosomal DNA?
    • 1) The strand itself
    • 2) the strand wrapped around thousands of histones
    • 3) The histones (ball like); form regions to make the DNA more compact
    • 4) All regions can be linked together to make DNA tiny
  62. What is the purpose of DNA initiation
    The get DNA polymerase attached to the DNA thta is to be copied
  63. What are the three steps of initiation of DNA replication?
    • 1) Unwinding the DNA - must be opened by DNA helicase so that the initiation complex can bind to the DNA
    • 2) Synthesis of an RNA primer - primase binds to DNA and makes a short copy of the DNA which is called an RNA primer
    • 3) Binding of the DNA rep complex - DNA rep complex binds to RNA primer on DNA
  64. What are the parts of DNA replication complex?
    • 1) Helicase to unwind DNA
    • 2) Two DNA polymerases that replicate DNA in a 5 to 3 direction
  65. What is Elongation (copying of DNA)
    • copying of the DNA
    • involves leading strand and lagging strand
  66. Describe the Termination of circular DNA replication
    • they are linked like a chain
    • there are enzymes that break one of the chromosomes and relink it so that they are separated
  67. Describe termination of linear chromosome replication
    in eukaryotes telomerase copies the last bit of DNA such that the new chromosomes are the same length as the old chromosomes
  68. Describe eukaryotic mRNA processing
    • 1) 5' end is capped
    • 2) Addtition of a poly-A tail
    • 3) Removal of introns through splicing
  69. What are the three functions of a ribosome?
    • 1) docking site from mRNA and inititator tRNA
    • 2) docking site for additional tRNA that recognizes the mRNA
    • 3) Traspeptidation enzyme which allows two amino acids to be joined together to form a peptide chain or protein
  70. Describe the initiation process of translation
    • the ribosome binds to the mRNA molecule and rapidly scans until it finds an intitiator site
    • the ribosome positions itself such that the P site is over the initiator site where the initiator or first tRNA can bind
    • upon binding of initiator tRNA the ribosome now assumes an active state with the Asite open
  71. Elongation during protein synthesis
    • 1) filling of A site
    • 2) Transpeptidation
    • 3) translocation
    • 4) Ejection of the rRNA*
  72. what is generalized transduction
    • virus penetrates bacterial cell and enter the lytic cycle
    • viral DNA begins to replicate immediately in the bacterial cytoplasm
    • during replication enzymes accidentally use some bacterial DNA to make new viruses
    • bacterial genes are randomly packaged into new viruses
    • some new viruses have bacterial DNA and no viral DNA
    • transducing viruses enter recipient bacterium
    • donor bacterial genes are incorporated into the chromosome of recipient bacterium
  73. How is specialized transduction different from generalized?
    • viruses penetrate and enter the lysogenic cycle
    • replication begins at a later time
    • during release from chromosome in replication, viral DNA accidentally excises bacterial DNA to make new viruses
    • bacterial genes adjacent to previously incorporated virus are packaged into new virus
  74. What are the steps of recombination?
    • 1) Enzyme causes a double stranded break
    • 2) single stranded protruding 3 ends are created by degrading the 5 strand
    • 3) strand invasion occurs - strand adheres to the other DNA homolog
    • 4) (eukaryotes only) DNA synthesis copies the DNA - usually for 1000 more bases
    • 5) A holliday junction forms and is resolved into to separate DNA molecules
  75. What are the three steps of transformation?
    • 1) external DNA is bound by proteins on the cell surface
    • 2) DNA is taken up into the cell as either a single strand or a double strand
    • 3) foreign DNA is incorporated into the cell's genetic material through recombination

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