Microbial genetics


                                Bios 10115
                             February 18, 2010


Additiona...
“Central Dogma” (DNARNAProtein)
 Genetic information of all
  cells is in DNA
 DNA is duplicated during
  the process ...
DNA
 4 nucleotides
      GATC
 Nucleotides consist of
  pentose sugar (5’ and 3’
  positions), phosphate and
  backbone
 Double stranded-held together
  by hydrogen bonding-base
  pairs
      A-T (2 H bonds)
      G-C (3 H bonds)
 Chromos...
Double Helix – ________ strands
DNA higher order structure

E. coli has 1.5mm of DNA
Figure 10.1a: An electron micrograph of an E. coli cell immediately after
                  disruption. The tangled mass i...
Eukaryotic DNA higher order structure




                        “beads on a string”
Information transfer



 Replication
    DNA makes new (is the template for) DNA
 Transcription
    DNA is the templat...
DNA replication
 New strand is made as
  complement of template
  strand
 Each daughter double
  helix has one parental
...
The DNA replication fork (E. coli)

Leading and lagging strands




 DNA polymerases can only move in one direction
http://www.dnai.org/a/index.html
   (animations of replication,




E. Coli replicates 1000 bases per second
Replication of circular DNA




Also see fig 10.2 of your book
RNA
 Ribose instead of deoxyribose
 Uracil instead of Thymine
 Single Stranded (except some viruses)


 Messenger (mRN...
Transcription




 An RNA copy of DNA must be made first before
  proteins can be synthesized
 Transcription requires th...
Translation
 Translation is the
  process of
  synthesizing
  protein from RNA
 Three types of
  RNA involved
Figure 4.8: The translation process
The Genetic Code
 Codon-set of 3 nucleotides
  that encodes an amino
  acid
 Amino acid-building block
  of protein
 St...
Figure 4.9: A summary view of protein synthesis
Open reading frames
Mutations- changes in DNA
Genotype -genetic info
 Always changed by a mutation
Phenotype -outward appearance
 May not ch...
Mutations (cont.)
Frameshift mutations
 A deletion or insertion of
  one or more bases
 Changes ORF
 Usually change
  p...
Mutations (cont.)
 Spontaneous mutations
     Occur in the absence of any known agent
     Arise during DNA replication...
Mutagens
 Chemical
      Many different effects
       at molecular level
      Base analogs
      Alkylating agents
 ...
Plasmids
Small, circular extra-chromosomal
  DNA
Do not carry essential genes
   May carry helpful genes
Replicate indepen...
Gene transfer
 Vertical gene transfer-parents to offspring
 Lateral (or horizontal) gene transfer-passing
   of genes wi...
Also see figs 10.5-10.9 in your book
Figure 10.9a: Bacterial transformation
                                       Free DNA taken up by cell

© National Librar...
Genetic exchange-Transformation
Streptococcus pneumoniae (pneumococcus) +/- capsule




1928-pneumococcus expt (Griffith)
...
Transduction
 Transfer of DNA by a _____________
Conjugation: _______ transfer of plasmids

 Ability is encoded by
  _________
 Donor cell produces ____
 New population...
Manipulation of DNA and
Genetic engineering
Tools to manipulate DNA
 ___________________
                                  Sequences usually palindromic
  (enzymes)
...
Figure 10.10a: A restriction enzyme cuts through two strands of a DNA
                 molecule to produce two fragments.
Figure 10.10b: The recognition sites of several restriction enzymes
Recombinant DNA technology
 Recombinant DNA
      DNA from _________
 Transgenic or recombinant
  organism
      Organ...
Figure 10.11A-B: Construction of a recombinant DNA molecule
Figure 10.11C-E: Construction of a recombinant DNA molecule
Figure 10.12A-C: Developing new products using genetic engineering
Figure 10.12D-G: Developing new products using genetic engineering
Feb18lecture Post Key
Feb18lecture Post Key
Feb18lecture Post Key
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  • Feb18lecture Post Key

    1. 1. Microbial genetics Bios 10115 February 18, 2010 Additional reading from your book is suggested-Ch 4 pp 61-80
    2. 2. “Central Dogma” (DNARNAProtein)  Genetic information of all cells is in DNA  DNA is duplicated during the process of DNA Replication  Transfer of genetic information to RNA occurs during Transcription  RNA is converted to protein during translation
    3. 3. DNA  4 nucleotides  GATC  Nucleotides consist of pentose sugar (5’ and 3’ positions), phosphate and backbone
    4. 4.  Double stranded-held together by hydrogen bonding-base pairs  A-T (2 H bonds)  G-C (3 H bonds)  Chromosome  Threadlike Double helix of DNA  Prokaryotes-Circular (most)  Eukaryotes- linear  Virus-circular or linear
    5. 5. Double Helix – ________ strands
    6. 6. DNA higher order structure E. coli has 1.5mm of DNA
    7. 7. Figure 10.1a: An electron micrograph of an E. coli cell immediately after disruption. The tangled mass is the organism’s DNA. © H. Potter-D. Dressler/Visuals Unlimited.
    8. 8. Eukaryotic DNA higher order structure “beads on a string”
    9. 9. Information transfer  Replication  DNA makes new (is the template for) DNA  Transcription  DNA is the template for RNA  Translation  RNA is the template for proteins A template is a pattern that is faithfully copied
    10. 10. DNA replication  New strand is made as complement of template strand  Each daughter double helix has one parental strand and one newly synthesized strand  DNA replication always occurs 5’-3’  5’ Phosphate attaches to 3’ hydroxyl using DNA Polymerase
    11. 11. The DNA replication fork (E. coli) Leading and lagging strands DNA polymerases can only move in one direction
    12. 12. http://www.dnai.org/a/index.html (animations of replication, E. Coli replicates 1000 bases per second
    13. 13. Replication of circular DNA Also see fig 10.2 of your book
    14. 14. RNA  Ribose instead of deoxyribose  Uracil instead of Thymine  Single Stranded (except some viruses)  Messenger (mRNA)  Transfer (tRNA) All transcribed from DNA  Ribosomal (rRNA)
    15. 15. Transcription  An RNA copy of DNA must be made first before proteins can be synthesized  Transcription requires the enzyme RNA Polymerase
    16. 16. Translation  Translation is the process of synthesizing protein from RNA  Three types of RNA involved
    17. 17. Figure 4.8: The translation process
    18. 18. The Genetic Code  Codon-set of 3 nucleotides that encodes an amino acid  Amino acid-building block of protein  Start Codon - AUG- methionine  Stop codon- terminator- UAA, UAG, UGA
    19. 19. Figure 4.9: A summary view of protein synthesis
    20. 20. Open reading frames
    21. 21. Mutations- changes in DNA Genotype -genetic info  Always changed by a mutation Phenotype -outward appearance  May not change with mutation Point mutations  A single nucleotide has been changed  A single codon is changed  May or may not change amino acid sequence (silent mutation)
    22. 22. Mutations (cont.) Frameshift mutations  A deletion or insertion of one or more bases  Changes ORF  Usually change phenotype
    23. 23. Mutations (cont.)  Spontaneous mutations  Occur in the absence of any known agent  Arise during DNA replication  Bacterial genes have a relatively high spontaneous generation rate  Induced mutations  Caused by mutagens
    24. 24. Mutagens  Chemical  Many different effects at molecular level  Base analogs  Alkylating agents  Deaminating agents  Acridine derivatives  Radiation  Thymine dimers
    25. 25. Plasmids Small, circular extra-chromosomal DNA Do not carry essential genes May carry helpful genes Replicate independently of chromosome Over 300 naturally occurring plasmids have been isolated from E. coli
    26. 26. Gene transfer  Vertical gene transfer-parents to offspring  Lateral (or horizontal) gene transfer-passing of genes within a generation  Transformation  Transduction (virus mediated)  Conjugation http://www.microbelibrary.org/microbelibrary/files/ccImages/Articleimages/ Mondomedia/4hirez.mov
    27. 27. Also see figs 10.5-10.9 in your book
    28. 28. Figure 10.9a: Bacterial transformation Free DNA taken up by cell © National Library of Medicine
    29. 29. Genetic exchange-Transformation Streptococcus pneumoniae (pneumococcus) +/- capsule 1928-pneumococcus expt (Griffith) 1944-transforming compound is DNA 1953-structure of DNA Also fig 4.2 of your book
    30. 30. Transduction  Transfer of DNA by a _____________
    31. 31. Conjugation: _______ transfer of plasmids  Ability is encoded by _________  Donor cell produces ____  New population can gain plasmid very quickly
    32. 32. Manipulation of DNA and Genetic engineering
    33. 33. Tools to manipulate DNA  ___________________ Sequences usually palindromic (enzymes)  Derived from _______  Protect bacteria from _______________  Recognize specific small sequences of DNA and ___ _________ leaving “sticky” (staggered) or “blunt” (straight) ends  Bacteria’s own DNA _________ by methylation
    34. 34. Figure 10.10a: A restriction enzyme cuts through two strands of a DNA molecule to produce two fragments.
    35. 35. Figure 10.10b: The recognition sites of several restriction enzymes
    36. 36. Recombinant DNA technology  Recombinant DNA  DNA from _________  Transgenic or recombinant organism  Organism derived from recombined DNA  _______  Self replicating DNA (plasmid)
    37. 37. Figure 10.11A-B: Construction of a recombinant DNA molecule
    38. 38. Figure 10.11C-E: Construction of a recombinant DNA molecule
    39. 39. Figure 10.12A-C: Developing new products using genetic engineering
    40. 40. Figure 10.12D-G: Developing new products using genetic engineering

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