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Microbial Genetics 
Ariane Ruby B. Sogo-an 
MST Biology
Microbial Genetics 
• Mutation in Bacteria 
• Genetics Exchange in Bacteria 
• Recombination and Genetic Engineering
Learning Objectives: 
1. Define Mutation. 
2. Explain the mechanisms involved in Mutation. 
3. Familiarize the processes i...
Report Outline 
• Nucleic Acids 
• Central Dogma 
• DNA Replication in Bacteria 
• RNA Synthesis in Bacteria 
• Protein Sy...
Genetics 
• Genetics is a study of Heredity. 
• HOW the information contained in Nucleic Acids is expressed? 
• HOW this t...
Nucleic Acids 
• Nucleic Acids are large organic molecules that are found in ALL 
cells. 
• Two Types: 
• DNA (Deoxyribonu...
Nucleic Acids 
• Nucleic Acids are large organic molecules that are found in ALL 
cells. 
• Two Types: 
• DNA (Deoxyribonu...
Nucleic Acids 
• Composition: 
• Constructed from a string of small molecules called 
NUCLEOTIDES.
Component of a Nucleotide
Nitrogenous Base
Primary Structure of RNA
Primary Structure of DNA
DNA and RNA
Ribonucleic Acids 
• RNA are normally single stranded molecules. 
• Types: (based on their function) 
• mRNA (Messenger) 
...
Deoxyribonucleic Acids 
• Double Stranded, with each strand wrapped around the other 
in a helical fashion forming a doubl...
Deoxyribonucleic Acids 
• Determines the characteristics of an organism and maintains 
and controls the vital processes of...
The Central Dogma
The Central Dogma 
• Gene 
• The unit of genetic information or hereditary material contained 
in DNA molecule. 
• Sequenc...
The Central Dogma 
• Theory stating that genes guide the synthesis of mRNA and in 
turn, directs the order in which amino ...
The Central Dogma 
• Reverse Transcription 
• Example: Certain cancer causing viruses (retroviruses) are able to 
synthesi...
DNA Replication in Bacteria 
• Genome – total genetic information in bacteria which consists 
of circular DNA molecules fo...
DNA Replication in Bacteria 
• The bacterial chromosomes contains most of the genetic 
information of bacteria and is atta...
DNA Replication in Bacteria 
• Both DNA strands are duplicated with each strands functions 
as a template that specifies t...
DNA Replication
DNA Replication 
• 1. The original double helix molecule. 
• 2. Helicase enzyme breaks the hydrogen bonds between 
complem...
RNA Synthesis in Bacteria 
• Transcription 
• Involves the assembly of nucleotides by an enzyme called RNA 
polymerase tha...
RNA Synthesis in Bacteria 
• After mRNA is made, it will be used as a guide to make 
proteins. 
• Ribosomal RNA, after its...
MUTATION
The Genetic Code 
• The start codon is AUG. Methionine is the only amino acid 
specified by just one codon, AUG. 
• The st...
Mutation: Base Substitution (Point 
Mutations) 
G 
C 
Glu 
(d) Run-on mutation 
G 
C 
(a) Silent mutation
Mutation: Insertions and Deletions 
Figure 8.17a, d 
THEBIGCATATETHERAT 
THEBIGCBATATETHERAT
Summary of Mutation Types 
Run-on mutation 
Stop codon lost so 
protein is extra long 
(can also produce 
nonsense and run...
Spontaneous and Induced Mutation 
• Spontaneous mutation rate = 1 in 109 (a billion) replicated base pairs 
or 1 in 106 ( ...
Mutagen 
• Mutation relevant 
• Cause DNA damage that can be converted to mutations.
Physical mutagens 
High-energy ionizing radiation: X-rays and g-rays  
strand breaks and base/sugar destruction 
Nonioniz...
Chemical Mutagens 
Base pair altering chemicals (base 
modifiers) deaminators like 
nitrous acid, nitrosoguanidine, 
or al...
BASE PAIR ALTERING CHEMICALS
Deaminating Agent 
• *Deaminating agent - Nitrous acid - removes the anime group 
from Adenine and Cytosine 
• Nitrous aci...
BASE ANALOGS
Alkylating agents 
• Alkylating agents like EMS/MMS(ethyl/methly methyl 
sulphonate) add methyl groups to Guanosine . Bulk...
Hydroxilating Agents 
• Addition of OH (Hydroxyl Group) 
hydroxylamine (HA)
Intercalating Agents 
• Intercalation agents are compounds that can slide between 
the nitrogenous bases in a DNA molecule...
Chemical FrameshiftMutagens Intercalate into DNA 
Aflatoxin from 
Aspergillus fungus 
growing on corn 
Benzpyrene in 
ciga...
Mutation: Ionizing Radiation 
• Ionizing radiation (X rays, gamma rays, UV light) causes the formation 
of ions that can r...
X-rays and Gamma Rays Cause 
Breaks in DNA
Ionizing Radiation: UV 
• UV radiation causes 
thymine dimers, which 
block replication. 
• Light-repair separates 
thymin...
MDufilho 7/6/11 
53 
Genetic Transfer 
• Horizontal Gene Transfer Among Prokaryotes 
• Horizontal gene transfer 
• Donor c...
Bacterial Sexual Processes 
• Eukaryotes have the processes of meiosis to reduce 
diploids to haploidy, and fertilization ...
Transformation 
• We aren’t going to speak much of this process, except to 
note that it is very important for recombinant...
Figure 7.33 Transformation in Streptococcus pneumoniae-overview 
MDufilho 7/6/11 
56
Conjugation 
• Conjugation is the closest analogue in 
bacteria to eukaryotic sex. 
• The ability to conjugate is conferre...
Figure 7.35 Bacterial conjugation-overview 
MDufilho 7/6/11 
58 
F plasmid Origin of 
transfer 
Conjugation pilus Chromoso...
Figure 7.36 Conjugation involving an Hfr cell-overview 
MDufilho 7/6/11 
59 
Donor chromosome 
Pilus 
F+ cell 
Hfr cell 
P...
Hfr Conjugation 
• When it exists as a free plasmid, 
the F plasmid can only transfer 
itself. This isn’t all that useful ...
Transduction 
• Transduction is the process of moving bacterial DNA from 
one cell to another using a bacteriophage. 
• Ba...
Figure 7.34 Transduction-overview 
MDufilho 7/6/11 
62 
Bacteriophage 
Phage injects its DNA. 
Phage enzymes 
degrade host...
General Phage Life Cycle 
• 1. Phage attaches to the cell 
and injects its DNA. 
• 2. Phage DNA replicates, 
and is transc...
Why do chromosomes undergo 
recombination? 
Deleterious mutations would accumulate in 
each chromosome 
Recombination gene...
Recombination 
ABCDEFGHIJKLMNOPQRSTUVWXYZ 
abcdefghijklmnopqrstuvwxyz 
ABCDEFGhijklmnoPQRSTUVWXYZ 
abcdefgHIJKLMNOpqrstuvw...
Mitotic and meiotic recombination 
Recombination can occur both during mitosis 
and meiosis 
Only meiotic recombination se...
Recombination mechanisms 
Best studied in yeast, bacteria and phage 
Recombination is mediated by the breakage 
and joinin...
Benefits of recombination 
• Greater variety in offspring: Generates new combinations of 
alleles 
• Negative selection ca...
Genetic Engineering
What is genetic engineering??? 
Genetic engineering: is the artificial manipulation 
or alteration of genes. 
Genetic Engi...
Some important terms!!! 
Recombinant DNA: the altered DNA is called 
recombinant DNA ( recombines after small section of 
...
Genetic Engineering breaks the species 
barrier!!! 
• Genetic engineering allows DNA from different species 
to be joined ...
Genetic engineering breaks the species 
barrier!!! 
• Examples of cross-species transfer of genes: 
- a human gene inserte...
Alternative names for genetic engineering: 
• Genetic Manipulation 
• Genetic Modification 
• Recombinant DNA Technology 
...
Tools used in genetic engineering!!! 
• Source of DNA: Target (foreign) DNA – DNA taken from 
one organism to be placed in...
Tools Used in Genetic Engineering 
Restriction Enzymes: 
- are special enzymes used to cut the DNA at specific 
places. 
-...
Restriction enzymes 
DNA 1 DNA 2
Tools used in Genetic Engineering 
DNA Ligase: enzyme which acts like a glue sticking 
foreign DNA to DNA of the cloning v...
Process of Genetic Engineering 
Five steps involved in this process: 
1. Isolation 
2. Cutting 
3. Insertion (Ligation) 
4...
Process of Genetic Engineering 
1. Isolation: 
• Removal of human DNA (containing target gene). 
• Removal of plasmid (bac...
Process of Genetic Engineering 
Insertion: 
• means that target gene is placed into the DNA of 
the plasmid or cloning vec...
Applications of Genetic Engineering 
You must know three applications: one involving a plant, 
one animal and one for a mi...
Applications of Genetic Engineering 
Animals: 
There is a growing trend to experiment with inserting 
human genes into the...
Applications of Genetic Engineering 
Animals: Sheep produce human clotting factor 
• A human gene has been inserted into t...
Pharming – using animals to make pharmaceuticals
Applications of Genetic Engineering 
Micro-organisms: Bacteria make insulin 
• The human insulin gene has been inserted in...
Ethical Issues in Genetic Engineering 
GMO’s as a food source: 
Outlined below are some fears associated with the use of 
...
Ethical Issues in Genetic Engineering 
Animal Welfare: 
• There is serious concern that animals will suffer as a 
result o...
Ethical Issues in Genetic Engineering 
Genetic Engineering in Humans: 
The following issues are a cause for concern: 
• If...
END OF REPORT
Microbial genetics microbiology ar
Microbial genetics microbiology ar
Microbial genetics microbiology ar
Microbial genetics microbiology ar
Microbial genetics microbiology ar
Microbial genetics microbiology ar
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Microbial Genetics

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Microbial genetics microbiology ar

  1. 1. Microbial Genetics Ariane Ruby B. Sogo-an MST Biology
  2. 2. Microbial Genetics • Mutation in Bacteria • Genetics Exchange in Bacteria • Recombination and Genetic Engineering
  3. 3. Learning Objectives: 1. Define Mutation. 2. Explain the mechanisms involved in Mutation. 3. Familiarize the processes involved on how Genetic Information are transferred in Bacteria 4. Give the importance of Recombination and Genetic Engineering
  4. 4. Report Outline • Nucleic Acids • Central Dogma • DNA Replication in Bacteria • RNA Synthesis in Bacteria • Protein Synthesis in Bacteria • Changes in the DNA molecule through Mutation • Transfer of Genetic Information in Bacteria
  5. 5. Genetics • Genetics is a study of Heredity. • HOW the information contained in Nucleic Acids is expressed? • HOW this type of molecule is duplicated? • HOW this duplicated molecules are transmitted to progeny?
  6. 6. Nucleic Acids • Nucleic Acids are large organic molecules that are found in ALL cells. • Two Types: • DNA (Deoxyribonucleic Acid) • directs protein production • RNA (Ribonucleic Acid)
  7. 7. Nucleic Acids • Nucleic Acids are large organic molecules that are found in ALL cells. • Two Types: • DNA (Deoxyribonucleic Acid) • directs protein production • RNA (Ribonucleic Acid)
  8. 8. Nucleic Acids • Composition: • Constructed from a string of small molecules called NUCLEOTIDES.
  9. 9. Component of a Nucleotide
  10. 10. Nitrogenous Base
  11. 11. Primary Structure of RNA
  12. 12. Primary Structure of DNA
  13. 13. DNA and RNA
  14. 14. Ribonucleic Acids • RNA are normally single stranded molecules. • Types: (based on their function) • mRNA (Messenger) • tRNA (Transfer) • rRNA (Ribosomal) • Look for specific example
  15. 15. Deoxyribonucleic Acids • Double Stranded, with each strand wrapped around the other in a helical fashion forming a double helix. • Hydrogen bond is specific since A-T (or U in RNA) and G-C ATCCGGC TAGGCCG • Molecule is more stable.
  16. 16. Deoxyribonucleic Acids • Determines the characteristics of an organism and maintains and controls the vital processes of all cells. • How is genetic information expressed? • Transcription (involves formation of RNA molecule using DNA as a template) • Translation (consists of the synthesis of a protein using the genetic information in the RNA)
  17. 17. The Central Dogma
  18. 18. The Central Dogma • Gene • The unit of genetic information or hereditary material contained in DNA molecule. • Sequenced nucleotide in the DNA molecule that codes for RNA molecule and ultimately for the synthesis of a protein.
  19. 19. The Central Dogma • Theory stating that genes guide the synthesis of mRNA and in turn, directs the order in which amino acids are resembled to form protein. • Also postulates that a DNA molecule can direct its own replication by giving rise of two identical DNA molecule.
  20. 20. The Central Dogma • Reverse Transcription • Example: Certain cancer causing viruses (retroviruses) are able to synthesize DNA using RNA as a template.
  21. 21. DNA Replication in Bacteria • Genome – total genetic information in bacteria which consists of circular DNA molecules found within the cell. • Most of the genome is contained in a single bacterial chromosome, although smaller pieces of circular DNA called plasmids may also carry a few important genes such as those coding for resistance to microbial drugs.
  22. 22. DNA Replication in Bacteria • The bacterial chromosomes contains most of the genetic information of bacteria and is attached to the plasma membrane. • Size of the chromosomes varies from species to species. • Example: (per chromosome) • Mycoplasma – fewer than 1 M nucleotide base pairs and a genome can code for 1000 proteins. • E. Coli – 4.5 M nucleotide base pairs that can code for 4500 proteins.
  23. 23. DNA Replication in Bacteria • Both DNA strands are duplicated with each strands functions as a template that specifies the sequence of bases in the newly formed complementary strand. • DNA polymerases • Process nucleotides from the cytoplasm that are complementary to the template and fit them into place. • Parental and New strand = semiconservative.
  24. 24. DNA Replication
  25. 25. DNA Replication • 1. The original double helix molecule. • 2. Helicase enzyme breaks the hydrogen bonds between complementary base pairs. This unzips the double helix at a position called the replication fork. • 3. There is an abundant supply of nucleotides in the nucleus for the formation of the new polynucleotides. • 4. Nucleotides base pair to the bases in the original strands. • 5. DNA polymerase joins together the nucleotides together with strong covalent phosphodiester bonds To form a new complementary polynucleotide strand. • 6. The double strand reforms a double helix under the influence of an enzyme. • 7 Two copies of the DNA molecule form behind the replication fork. These are the new daughter chromosomes.
  26. 26. RNA Synthesis in Bacteria • Transcription • Involves the assembly of nucleotides by an enzyme called RNA polymerase that uses a strand of DNA as its template. • Begins when RNA polymerase binds to the DNA at the promoter site near the gene to be transcribed. • RNA polymerase travels along the length of the DNA strand until it reaches a termination site.
  27. 27. RNA Synthesis in Bacteria • After mRNA is made, it will be used as a guide to make proteins. • Ribosomal RNA, after its made, becomes associated with proteins to form ribosomes. • tRNA are small RNA molecules that are involved in translating the information in the mRNA into proteins.
  28. 28. MUTATION
  29. 29. The Genetic Code • The start codon is AUG. Methionine is the only amino acid specified by just one codon, AUG. • The stop codons are UAA, UAG, and UGA. They encode no amino acid. The ribosome pauses and falls off the mRNA.
  30. 30. Mutation: Base Substitution (Point Mutations) G C Glu (d) Run-on mutation G C (a) Silent mutation
  31. 31. Mutation: Insertions and Deletions Figure 8.17a, d THEBIGCATATETHERAT THEBIGCBATATETHERAT
  32. 32. Summary of Mutation Types Run-on mutation Stop codon lost so protein is extra long (can also produce nonsense and run-ons)
  33. 33. Spontaneous and Induced Mutation • Spontaneous mutation rate = 1 in 109 (a billion) replicated base pairs or 1 in 106 ( a million) replicated genes. Mistakes occur during DNA Replication just before cell division. This is natural error rate of DNA polymerase. • Mutagens increase mistakes to to 10–5 (100 thousand) or 10–3 ( a thousand) per replicated gene
  34. 34. Mutagen • Mutation relevant • Cause DNA damage that can be converted to mutations.
  35. 35. Physical mutagens High-energy ionizing radiation: X-rays and g-rays  strand breaks and base/sugar destruction Nonionizing radiation : UV light pyrimidine dimers Chemical mutagens Base analogs: direct mutagenesis Nitrous acid: deaminates C to produce U Alkylating agents Intercalating agents Lesions-indirect mutagenesis 1 Mutaagenesis
  36. 36. Chemical Mutagens Base pair altering chemicals (base modifiers) deaminators like nitrous acid, nitrosoguanidine, or alkylating agents like cytoxan Base analogues “mimic” certain bases but pair with others - E.g. 5-fluorouracil, cytarabine Acts like a “C” cytarabine cytoxan Nitrous acid
  37. 37. BASE PAIR ALTERING CHEMICALS
  38. 38. Deaminating Agent • *Deaminating agent - Nitrous acid - removes the anime group from Adenine and Cytosine • Nitrous acid is a deaminating agent that converts cytosine to uracil, adenine to hypoxanthine, and guanine to xanthine. The hydrogen-bonding potential of the modified base is altered, resulting in mispairing.
  39. 39. BASE ANALOGS
  40. 40. Alkylating agents • Alkylating agents like EMS/MMS(ethyl/methly methyl sulphonate) add methyl groups to Guanosine . Bulky attachment to the side groups or bases.
  41. 41. Hydroxilating Agents • Addition of OH (Hydroxyl Group) hydroxylamine (HA)
  42. 42. Intercalating Agents • Intercalation agents are compounds that can slide between the nitrogenous bases in a DNA molecule. • This tends to cause a greater likelihood for slippage during replication, resulting in an increase in frameshift mutations. • Example (Sodium Azide)
  43. 43. Chemical FrameshiftMutagens Intercalate into DNA Aflatoxin from Aspergillus fungus growing on corn Benzpyrene in cigarette smoke AT GC TA GC CG AT GC TA GC CG AT GC CG TA GC CG Carboplatin (anti-cancer drug) Daunarubicin (anti-cancer drug) Bleomycin (anti-cancer drug produced by Streptomyces)
  44. 44. Mutation: Ionizing Radiation • Ionizing radiation (X rays, gamma rays, UV light) causes the formation of ions that can react with nucleotides and the deoxyribose-phosphate backbone. • Nucleotide excision repairs mutations
  45. 45. X-rays and Gamma Rays Cause Breaks in DNA
  46. 46. Ionizing Radiation: UV • UV radiation causes thymine dimers, which block replication. • Light-repair separates thymine dimers • Sometimes the “repair job” introduces the wrong nucleotide, leading to a point mutation. Figure 8.20
  47. 47. MDufilho 7/6/11 53 Genetic Transfer • Horizontal Gene Transfer Among Prokaryotes • Horizontal gene transfer • Donor cell contributes part of genome to recipient cell • Three types • Transformation • Transduction • Bacterial conjugation © 2012 Pearson Education Inc.
  48. 48. Bacterial Sexual Processes • Eukaryotes have the processes of meiosis to reduce diploids to haploidy, and fertilization to return the cells to the diploid state. Bacterial sexual processes are not so regular. However, they serve the same aim: to mix the genes from two different organisms together. • The three bacterial sexual processes: • 1. conjugation: direct transfer of DNA from one bacterial cell to another. • 2. transduction: use of a bacteriophage (bacterial virus) to transfer DNA between cells. • 3. transformation: naked DNA is taken up from the environment by bacterial cells.
  49. 49. Transformation • We aren’t going to speak much of this process, except to note that it is very important for recombinant DNA work. The essence of recombinant DNA technology is to remove DNA from cells, manipulate it in the test tube, then put it back into living cells. In most cases this is done by transformation. • In the case of E. coli, cells are made “competent” to be transformed by treatment with calcium ions and heat shock. E. coli cells in this condition readily pick up DNA from their surroundings and incorporate it into their genomes.
  50. 50. Figure 7.33 Transformation in Streptococcus pneumoniae-overview MDufilho 7/6/11 56
  51. 51. Conjugation • Conjugation is the closest analogue in bacteria to eukaryotic sex. • The ability to conjugate is conferred by the F plasmid. A plasmid is a small circle of DNA that replicates independently of the chromosome. Bacterial cells that contain an F plasmid are called “F+”. Bacteria that don’t have an F plasmid are called “F-”. • F+ cells grow special tubes called “sex pilli” from their bodies. When an F+ cell bumps into an F- cell, the sex pilli hold them together, and a copy of the F plasmid is transferred from the F+ to the F-. Now both cells are F+. • Why aren’t all E. coli F+, if it spreads like that? Because the F plasmid can be spontaneously lost.
  52. 52. Figure 7.35 Bacterial conjugation-overview MDufilho 7/6/11 58 F plasmid Origin of transfer Conjugation pilus Chromosome F+ cell F– cell Donor cell attaches to a recipient cell with its pilus. Pilus may draw cells together. One strand of F plasmid DNA transfers to the recipient. F+ cell F+ cell Pilus The recipient synthesizes a complementary strand to become an F+ cell with a pilus; the donor synthesizes a complementary strand, restoring its complete plasmid.
  53. 53. Figure 7.36 Conjugation involving an Hfr cell-overview MDufilho 7/6/11 59 Donor chromosome Pilus F+ cell Hfr cell Pilus F+ cell (Hfr) F plasmid F– recipient Donor DNA Part of F plasmid F plasmid integrates into chromosome by recombination. Cells join via a conjugation pilus. Portion of F plasmid partially moves into recipient cell trailing a strand of donor’s DNA. Conjugation ends with pieces of F plasmid and donor DNA in recipient cell; cells synthesize complementary DNA strands. Donor DNA and recipient DNA recombine, making a recombinant F– cell. Incomplete F plasmid; cell remains F– Recombinant cell (still F–)
  54. 54. Hfr Conjugation • When it exists as a free plasmid, the F plasmid can only transfer itself. This isn’t all that useful for genetics. • However, sometimes the F plasmid can become incorporated into the bacterial chromosome, by a crossover between the F plasmid and the chromosome. The resulting bacterial cell is called an “Hfr”, which stands for “High frequency of recombination”. • Hfr bacteria conjugate just like F+ do, but they drag a copy of the entire chromosome into the F-cell.
  55. 55. Transduction • Transduction is the process of moving bacterial DNA from one cell to another using a bacteriophage. • Bacteriophage or just “phage” are bacterial viruses. They consist of a small piece of DNA inside a protein coat. The protein coat binds to the bacterial surface, then injects the phage DNA. The phage DNA then takes over the cell’s machinery and replicates many virus particles. • Two forms of transduction: • 1. generalized: any piece of the bacterial genome can be transferred • 2. specialized: only specific pieces of the chromosome can be transferred.
  56. 56. Figure 7.34 Transduction-overview MDufilho 7/6/11 62 Bacteriophage Phage injects its DNA. Phage enzymes degrade host DNA. Phage DNA Host bacterial cell (donor cell) Bacterial chromosome Phage with donor DNA (transducing phage) Cell synthesizes new phages that incorporate phage DNA and, mistakenly, some host DNA. Transducing phage Transducing phage injects donor DNA. Recipient host cell Donor DNA is incorporated into recipient’s chromosome by recombination. Transduced cell Inserted DNA
  57. 57. General Phage Life Cycle • 1. Phage attaches to the cell and injects its DNA. • 2. Phage DNA replicates, and is transcribed into RNA, then translated into new phage proteins. • 3. New phage particles are assembled. • 4. Cell is lysed, releasing about 200 new phage particles. • Total time = about 15 minutes.
  58. 58. Why do chromosomes undergo recombination? Deleterious mutations would accumulate in each chromosome Recombination generates genetic diversity
  59. 59. Recombination ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz ABCDEFGhijklmnoPQRSTUVWXYZ abcdefgHIJKLMNOpqrstuvwxyz
  60. 60. Mitotic and meiotic recombination Recombination can occur both during mitosis and meiosis Only meiotic recombination serves the important role of reassorting genes Mitotic recombination may be important for repair of mutations in one of a pair of sister chromatids
  61. 61. Recombination mechanisms Best studied in yeast, bacteria and phage Recombination is mediated by the breakage and joining of DNA strands
  62. 62. Benefits of recombination • Greater variety in offspring: Generates new combinations of alleles • Negative selection can remove deleterious alleles from a population without removing the entire chromosome carrying that allele • Essential to the physical process of meiosis, and hence sexual reproduction • Yeast and Drosophila mutants that block pairing are also defective in recombination, and vice versa!!!!
  63. 63. Genetic Engineering
  64. 64. What is genetic engineering??? Genetic engineering: is the artificial manipulation or alteration of genes. Genetic Engineering involves: • removing a gene (target gene) from one organism • inserting target gene into DNA of another organism • ‘cut and paste’ process.
  65. 65. Some important terms!!! Recombinant DNA: the altered DNA is called recombinant DNA ( recombines after small section of DNA inserted into it). Genetically Modified Organism (GMO): is the organism with the altered DNA.
  66. 66. Genetic Engineering breaks the species barrier!!! • Genetic engineering allows DNA from different species to be joined together. • This often results in combinations of DNA that would never be possible in nature!!! For this reason genetic engineering is not a natural process. • If DNA is transferred from one species to another the organism that receives the DNA is said to be transgenic.
  67. 67. Genetic engineering breaks the species barrier!!! • Examples of cross-species transfer of genes: - a human gene inserted into a bacterium - a human gene inserted into another animal - a bacterial gene placed in a plant
  68. 68. Alternative names for genetic engineering: • Genetic Manipulation • Genetic Modification • Recombinant DNA Technology • Gene Splicing • Gene Cloning
  69. 69. Tools used in genetic engineering!!! • Source of DNA: Target (foreign) DNA – DNA taken from one organism to be placed into the DNA of a second organism. • A cloning vector: Special kind of DNA that can accept foreign DNA and exactly reproduce itself and the foreign DNA e.g. Bacterial plasmid (loop of DNA found in bacteria).
  70. 70. Tools Used in Genetic Engineering Restriction Enzymes: - are special enzymes used to cut the DNA at specific places. - different enzymes cut DNA at specific base sequences known as a recognition site. For example i) One restriction enzyme will always cut DNA at the base sequence: GAATTC. ii) Another restriction enzyme only cuts at the sequence: GATC. - If DNA from two different organisms is cut with the same restriction enzyme the cut ends from both sources will be complementary and can easily stick together.
  71. 71. Restriction enzymes DNA 1 DNA 2
  72. 72. Tools used in Genetic Engineering DNA Ligase: enzyme which acts like a glue sticking foreign DNA to DNA of the cloning vector. • will only work if DNA from the two DNA sources has been cut with the same restriction enzyme i.e. sticky ends of cut DNA will be complementary to each other. Please note diagram illustrating use of restriction enzymes and DNA Ligase in production of recombinant DNA Fig. 19.6 pg. 195
  73. 73. Process of Genetic Engineering Five steps involved in this process: 1. Isolation 2. Cutting 3. Insertion (Ligation) 4. Transformation 5. Expression Note: The following example will explain how a human gene is inserted into a bacterium so that the bacterium can produce human insulin.
  74. 74. Process of Genetic Engineering 1. Isolation: • Removal of human DNA (containing target gene). • Removal of plasmid (bacterial DNA) from bacterium. 2. Cutting: • Both human DNA and plasmid DNA are cut with the same restriction enzyme. • Normally plasmid has only one restriction site while human DNA will have many restriction sites. Please note diagram 19.7 pg. 196
  75. 75. Process of Genetic Engineering Insertion: • means that target gene is placed into the DNA of the plasmid or cloning vector. • cut plasmids are mixed with human DNA sections allowing the cut ends to combine. Transformation Expression
  76. 76. Applications of Genetic Engineering You must know three applications: one involving a plant, one animal and one for a micro-organism. Plants: Weed killer-resistant crops • many types of crop plants have bacterial genes added to them. • these genes make the plants resistant to certain weed killers (herbicides). • this means that the weed killers kill the weeds but do not affect the transgenic plants.
  77. 77. Applications of Genetic Engineering Animals: There is a growing trend to experiment with inserting human genes into the DNA of other mammals. The transgenic animals formed in this way will then produce a human protein and secrete it into their milk or even into their eggs.
  78. 78. Applications of Genetic Engineering Animals: Sheep produce human clotting factor • A human gene has been inserted into the DNA of sheep. • This allows the adult sheep to produce a clotting chemical needed by haemophiliacs to clot their blood – produced in the milk of the sheep. Pharming: is the production of pharmaceuticals by genetically modified animals i.e. sheep, cows, goats etc.
  79. 79. Pharming – using animals to make pharmaceuticals
  80. 80. Applications of Genetic Engineering Micro-organisms: Bacteria make insulin • The human insulin gene has been inserted into a bacterium (E-coli). • This allows the bacterium to produce insulin for use by diabetics.
  81. 81. Ethical Issues in Genetic Engineering GMO’s as a food source: Outlined below are some fears associated with the use of GMO’s as a food source: • Cannibalism: – eating an animal containing a human gene is a form of cannibalism. - feeding GMO’s containing human genes to animals that would later be eaten by humans. • Religious reasons: – eating pig genes that are inserted into sheep would be offensive to Jews and Muslims. • Offensive to vegetarians/vegans: – eating animal genes contained in food plants cause concern.
  82. 82. Ethical Issues in Genetic Engineering Animal Welfare: • There is serious concern that animals will suffer as a result of being genetically modified. • use of growth hormones may cause limb deformation and arthritis as animals grow.
  83. 83. Ethical Issues in Genetic Engineering Genetic Engineering in Humans: The following issues are a cause for concern: • If tests are carried out for genetic diseases, who is entitled to see the results? • Tests on unborn babies – could this lead to abortion if a disease is shown to be present? • Insurance/lending companies – will they insist on genetic tests before they will insure/lend money to a person? • Need for legal controls over the uses to which human cells can be put. • Development and expansion of eugenics.
  84. 84. END OF REPORT

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