Bacterial Genetics <ul><li>Dr.T.V.Rao,MD </li></ul>
Genetics Guide Life
Understanding Genetics <ul><li>We resemble and differ because of Genetic configurations </li></ul><ul><li>Parents -  Son  ...
Genes are Eternal Run In Progeny
Watson  -  Crick Discovery of DNA
Beginning of Bacterial Genetics <ul><li>The principles of Genetics were applied to bacteria and viruses </li></ul><ul><li>...
DNA  A Complex Structure Makes Life
DNA ( Deoxyribonucleic Acid ) <ul><li>DNA is composed of Many Units of  </li></ul><ul><li>Adenine – Thymine  A – T </li></...
Structure of DNA
DNA <ul><li>A DNA molecule is composed of two chains of Nucleotides wound together in the form of a Double Helix </li></ul...
Structure of DNA <ul><li>Attached to each Deoxyribose  and phosphate residues arranged alternatively </li></ul><ul><li>Att...
How RNA differs from DNA <ul><li>RNA contains -  Sugar Ribose instead of Deoxyribose  </li></ul><ul><li>Uracil is present ...
DNA  -  RNA
Knowledge on DNA lead to advances in Molecular Biology <ul><li>Central dogma of Life – Deoxyribonucleic acid </li></ul><ul...
What is a   Code   in Genetics <ul><li>Code  is a unit consists of sequence of three Bases  </li></ul><ul><li>Code  is tri...
What is a   Gene <ul><li>Gene is a sequence of DNA carrying codons specifying for particular polypeptide. </li></ul><ul><l...
Bacterial Chromosome <ul><li>Contains a Double stranded molecules of DNA arranged in circular form. </li></ul><ul><li>Leng...
How bacterial Genome differs from Higher forms of Life <ul><li>Several stretches of DNA don't appear to function as codons...
Extra chromosomal Genetic Elements <ul><li>Bacteria posses Extra chromosomal genetic elements </li></ul><ul><li>Not Essent...
Plasmids <ul><li>Plasmids are circular DNA molecules present in the cytoplasm of the Bacteria </li></ul><ul><li>Capable of...
Plasmids   <ul><li>Plasmid seem to be ubiquitous in bacteria, May encode genetic information for properties </li></ul><ul>...
Plasmids <ul><li>Can be integrated with Chromosomal DNA </li></ul><ul><li>Episomes  -Integrated form of plasmid with DNA <...
Potentials of Plasmids <ul><li>Plasmids can be self transmissible and Non transmissible </li></ul><ul><li>Transfers the Se...
Classification of   Plasmids <ul><li>Incompatibility typing </li></ul><ul><li>Don't accommodate others which are similar <...
Genotypic and Phenotypic  variation <ul><li>Genome – Sum total of Gene that make up the genetic apparatus of cell establis...
What is   Phenotypic   expression <ul><li>Exhibit – different phenotypes </li></ul><ul><li>Appearance differs in different...
Different Enzymes Guided by Genomic configurations   <ul><li>Inducer enzyme acts in the presence of substrate </li></ul><u...
Principles of Genotypic variations <ul><li>Mutations </li></ul><ul><li>Genotypic by transfer of genes </li></ul><ul><li>Tr...
Mutations in   Bacteria <ul><li>Bacteria Multiply by asexual binary fission </li></ul><ul><li>Altered Nucleotide sequence ...
Mutations <ul><li>Mutation is a Random, Undirected, Heritable variation </li></ul><ul><li>Caused by alteration in the Nucl...
Mutations can occur in any sequence,inveitable, useful for Survival
Multiple Mutations <ul><li>Causes extensive chromosomal rearrangement </li></ul><ul><li>Missense mutation  -Triplet code i...
Mutations <ul><li>Supressor Mutation is reversal of mutant phenotype by another mutation at a point of DNA distant from th...
Mutations <ul><li>Conditional Lethal mutant may be Live under certain conditions </li></ul><ul><li>Common example is  temp...
Mutagenic Agents <ul><li>U V rays </li></ul><ul><li>Alkyl ting agents </li></ul><ul><li>Arcidine Dyes </li></ul>
GENE TRANSFER  Occurs by Complex Mechanisims
Transformation of Genetic material ( Gene Transfer ) <ul><li>Different Mechanisms  </li></ul><ul><li>Transformation </li><...
What is Transformation <ul><li>Transformation is defined as transfer of Genetic information through the activity of DNA </...
Griffith Phenomenon
Conjugation Laderberg - Tatum <ul><li>A process by which a Donor cell or male cell makes contact with another cell,  the r...
Conjugation - Transferring genes with plasmids <ul><li>Plasmids mediating conjugation carry genes coding for properties, o...
Conjugation
Pilus helps Conjugation <ul><li>Different types of Pilus are specified by different types of plasmids and can help in aid ...
F factor <ul><li>Transfer factor that contains the genetic information necessary for synthesis of Sex Pilus and for self t...
F factor helps transformation <ul><li>F +  called as Donor bacteria can transform </li></ul><ul><li>F -  into F +  cell </...
Transduction <ul><li>Transduction is defined as transfer of portion of DNA from one bacteria to another by Bacteriophages,...
Bacteriophages <ul><li>Are viruses that parasitize bacteria and consists of Nucleic acid core and a protein coat </li></ul...
DNA transfer through   Bacteriophages <ul><li>When the Phage particle infects another bacteria DNA transfer is effected an...
Types of DNA transfer through Bacteriophages
Transduction <ul><li>Generalized  involve any segment of DNA </li></ul><ul><li>Restricted  when specific Bacteriophages tr...
Transduction  Types <ul><li>Two types of Transduction </li></ul><ul><li>1  Lytic and 2 Lysogenic </li></ul><ul><li>1 Virul...
Transduction Lysogeny <ul><li>Bacteria called as lysogenic bacterium, in lysogenic bacteria prophages have an additional s...
Lysogenicity creates new characters <ul><li>Eg -  Lysogenic conversion in Diphtheria bacilli which acquires toxigenicity b...
Colicinogenic ( Col ) Factor <ul><li>Coli form Bacteria produce Colicins </li></ul><ul><li>Colicins are lethal to other En...
Resistance Transfer Factor RTF <ul><li>Plasmids – helps to spread multiple drug resistance </li></ul><ul><li>Discovered in...
RTF <ul><li>Shigella + E.coli excreted in the stool resistant to several drugs in vivo and vitro </li></ul><ul><li>Plasmid...
Sequence of RTF transmission
Hfr cell conjugating a Normal cell
Composition of RTF <ul><li>Plasmid consists of two components </li></ul><ul><li>A transfer factor RT, helps conjugational ...
R  factor <ul><li>R factor can contain several determinants as many as 8 or > 8 drugs </li></ul><ul><li>Guide the cell for...
Genesis of R factors <ul><li>In discriminate use of Antibiotics in vetenary Medicine has increased the spread of R factors...
Genetic Mechanisms of Drug Resistance <ul><li>Bacteria acquire drug resistance through several Mechanisms  </li></ul><ul><...
Genetic Mechanisms in Bacteria helps to spread the Infectious diseases
Mutations <ul><li>Mutatations can be </li></ul><ul><li>1 Stepwise mutation as in  Penicillin use </li></ul><ul><li>2 One s...
Other Mechanisms <ul><li>Use of Penicillin created resistant Staphylococcus by transduction </li></ul><ul><li>R factors cr...
Transposable Genetic Elements <ul><li>Structurally / Genetically – Discrete sequence of DNA – Move around in a cut and pas...
Transposons and R factor <ul><li>R forms may have evolved as a collection of Transposons </li></ul><ul><li>Each carrying G...
Molecular Genetics <ul><li>Analysis and manipulation of DNA using Biochemical and Microbiological techniques </li></ul>
Genetic Engineering <ul><li>Under standing Molecular genetics in Biochemistry fuels genetic Engineering  </li></ul><ul><li...
Genetic Engineering <ul><li>Isolation of Genes coding for any desired protein from Microorganism or from cell of higher li...
Genetic Engineering changing the Diagnostic and Therapeutic Protocols in  MEDICINE
Research on Gene transfer shapes the future of Science
Genitically Engineered Products <ul><li>Can prepare desired protein in pure form in economic way </li></ul><ul><li>Somatos...
Restriction Endonucleases <ul><li>A  restriction enzyme  (or  restriction  endonuclease ) is an  enzyme  that cuts double-...
Restriction Endonucleases Made the advances in Genetic Engineering
DNA Probes <ul><li>There are Radioactive </li></ul><ul><li>Biotinylated otherwise labelled copies united single stranded D...
Blotting Techniques <ul><li>Drug fragments obtained by restriction enzyme digestion on separation Gel can be transferred t...
Western Blotting <ul><li>In Western Blot Protein ( Antigen ) mixture is separated by SDS ( Sodium dodecyl sulfate – polyac...
Western Blot to confirm HIV Infections made land mark Diagnostic tool <ul><li>Western Blot testing is confirmatory test fo...
Polymerase chain reaction Kary B Mullis 1983 <ul><li>Rapid </li></ul><ul><li>Automatic amplification of specific DNA seque...
PCR -Sequences <ul><li>PCR consists of several cycles of sequential DNA replication where the products of first cycle beco...
Genetic Mapping <ul><li>Genetic sequences for Bacteriophages and virus </li></ul><ul><li>Genetic mapping is done most of t...
Newer Understanding on GENES
Human Genome Project
Human Genome Project <ul><li>C ompleted in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U...
Genetics are Complex  -  Leading the birth of BIOINFORMATICS
Genes Evolved and made us Men What NEXT ?
Are We Playing with Genes in the Right Direction ?
Understanding of human Genome is Changing the Future of Medicine
Created for Basic Teaching to Medical students Dr.T.V.Rao. MD email tvraodoctor2000@yahoo.co.in
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  1. 1. Bacterial Genetics <ul><li>Dr.T.V.Rao,MD </li></ul>
  2. 2. Genetics Guide Life
  3. 3. Understanding Genetics <ul><li>We resemble and differ because of Genetic configurations </li></ul><ul><li>Parents - Son - Daughter, how they resemble each other. </li></ul><ul><li>They breed true from Generation to Generation </li></ul><ul><li>But vary in small proportions in progeny. </li></ul><ul><li>Bacteria too obey the laws of Genetics </li></ul><ul><li>T.V.Rao MD </li></ul>
  4. 4. Genes are Eternal Run In Progeny
  5. 5. Watson - Crick Discovery of DNA
  6. 6. Beginning of Bacterial Genetics <ul><li>The principles of Genetics were applied to bacteria and viruses </li></ul><ul><li>Advances in Genetic process also of lead to fundamental advances in Biology and Biochemistry. </li></ul><ul><li>A Birth of New Branch of Science </li></ul><ul><li>Molecular Biology </li></ul><ul><li>T.V.Rao MD </li></ul>
  7. 7. DNA A Complex Structure Makes Life
  8. 8. DNA ( Deoxyribonucleic Acid ) <ul><li>DNA is composed of Many Units of </li></ul><ul><li>Adenine – Thymine A – T </li></ul><ul><li>Guanine – Cytosine G - C </li></ul><ul><li>A+ T </li></ul><ul><li>G+C proportion differ for each species </li></ul><ul><li>DNA replicates first unwinding at one end to form a fork </li></ul><ul><li>Each strand of fork acting as template for the synthesis of complementary strand </li></ul>
  9. 9. Structure of DNA
  10. 10. DNA <ul><li>A DNA molecule is composed of two chains of Nucleotides wound together in the form of a Double Helix </li></ul><ul><li>Each chain has back bone of Deoxyribose and Phosphates residues arranged alternatively </li></ul><ul><li>T.V.Rao MD </li></ul>
  11. 11. Structure of DNA <ul><li>Attached to each Deoxyribose and phosphate residues arranged alternatively </li></ul><ul><li>Attached to each Deoxyribose are of four nitrogen bases </li></ul><ul><li>Purines - Adenine, Guanine </li></ul><ul><li>Pyramidines </li></ul><ul><li>Thymidine and Cytosine </li></ul>
  12. 12. How RNA differs from DNA <ul><li>RNA contains - Sugar Ribose instead of Deoxyribose </li></ul><ul><li>Uracil is present instead of Thymine </li></ul><ul><li>Types of RNA </li></ul><ul><li>Messenger RNA mRNA </li></ul><ul><li>Ribosomal RNA rRNA </li></ul><ul><li>Transfer RNA tRNA </li></ul>
  13. 13. DNA - RNA
  14. 14. Knowledge on DNA lead to advances in Molecular Biology <ul><li>Central dogma of Life – Deoxyribonucleic acid </li></ul><ul><li>DNA carries the Genetic information </li></ul><ul><li>DNA is transcribed to RNA – Polypeptides </li></ul><ul><li>Cell Function depends upon specific polypeptides – Proteins – Enzymes </li></ul><ul><li>DNA is a store house of Protein synthesis </li></ul><ul><li>DNA acts a Template for synthesis of mRNA </li></ul><ul><li>Virus differs from other as they contains either DNA or RNA </li></ul>
  15. 15. What is a Code in Genetics <ul><li>Code is a unit consists of sequence of three Bases </li></ul><ul><li>Code is triplet A-T- C </li></ul><ul><li>A code can make single Amino acid </li></ul><ul><li>More than one code present for making similar sequence of Amino acid </li></ul><ul><li>AGA make Arginine </li></ul><ul><li>AGC, CGU, CGG, also code for similar Amino acid </li></ul><ul><li>Some Codons UAA don't code for any Amino acid called as Nonsense codon </li></ul>
  16. 16. What is a Gene <ul><li>Gene is a sequence of DNA carrying codons specifying for particular polypeptide. </li></ul><ul><li>DNA contains many Genes( A combinations of hundreds and thousands of Nucleotides ) </li></ul>
  17. 17. Bacterial Chromosome <ul><li>Contains a Double stranded molecules of DNA arranged in circular form. </li></ul><ul><li>Length 1,ooo microns. </li></ul><ul><li>Bacterial DNA contains about 4,000kilobases </li></ul><ul><li>I kb = 1000 base pairs ( A-T ) ( G-C) </li></ul><ul><li>Humans have about 4,000 kb pairs. </li></ul>
  18. 18. How bacterial Genome differs from Higher forms of Life <ul><li>Several stretches of DNA don't appear to function as codons,occurs between the coding sequences of Gene. called as INTRONS. </li></ul><ul><li>Coded are called as EXONS </li></ul><ul><li>In transcription introns are excised when form RNA before translated by ribosomal proteins. </li></ul>
  19. 19. Extra chromosomal Genetic Elements <ul><li>Bacteria posses Extra chromosomal genetic elements </li></ul><ul><li>Not Essential for survival of Bacteria </li></ul><ul><li>But makes the Bacteria Resistant to antibiotics, and makes them survive </li></ul><ul><li>Able to produce toxins </li></ul>
  20. 20. Plasmids <ul><li>Plasmids are circular DNA molecules present in the cytoplasm of the Bacteria </li></ul><ul><li>Capable of Autonomous replication </li></ul><ul><li>Can transfer genes from one cell to other </li></ul><ul><li>Act as vectors in Genetic engineering. </li></ul><ul><li>Can also present in Yeasts </li></ul>
  21. 21. Plasmids <ul><li>Plasmid seem to be ubiquitous in bacteria, May encode genetic information for properties </li></ul><ul><li>1 Resitance to Antibiotics </li></ul><ul><li>2 Bacteriocins production </li></ul><ul><li>3 Enterotoxin production </li></ul><ul><li>4 Enhanced pathogen city </li></ul><ul><li>5 Reduced Sensitivity to </li></ul><ul><li>mutagens </li></ul><ul><li>6 Degrade complex organic molecules </li></ul><ul><li>T.V.Rao MD </li></ul>
  22. 22. Plasmids <ul><li>Can be integrated with Chromosomal DNA </li></ul><ul><li>Episomes -Integrated form of plasmid with DNA </li></ul>
  23. 23. Potentials of Plasmids <ul><li>Plasmids can be self transmissible and Non transmissible </li></ul><ul><li>Transfers the Sex and Drug resistance with the help of restriction end nucleases </li></ul>
  24. 24. Classification of Plasmids <ul><li>Incompatibility typing </li></ul><ul><li>Don't accommodate others which are similar </li></ul><ul><li>Other methods of Classification </li></ul><ul><li>Centrifugation </li></ul><ul><li>Electrophoresis </li></ul><ul><li>Genetic methods </li></ul>
  25. 25. Genotypic and Phenotypic variation <ul><li>Genome – Sum total of Gene that make up the genetic apparatus of cell established as Genotype. </li></ul><ul><li>Hereditary constitution of cell this transmitted to its progeny </li></ul><ul><li>Phenotype – is the physical expression in a environment. Change according to environment. </li></ul>
  26. 26. What is Phenotypic expression <ul><li>Exhibit – different phenotypes </li></ul><ul><li>Appearance differs in different situations. </li></ul><ul><li>Eg Typhoid bacilli flagellated normally </li></ul><ul><li>But grown in Phenol agar don't grow flagella So flagella are lost physical variation </li></ul><ul><li>Lactose fermentation in E.coli dependent on Beta Galactosidase </li></ul><ul><li>When lacose present - test is positive </li></ul><ul><li>When lactose is absent - test turns negative </li></ul>
  27. 27. Different Enzymes Guided by Genomic configurations <ul><li>Inducer enzyme acts in the presence of substrate </li></ul><ul><li>Constitutive enzyme acts irrespective of presence or absence of enzyme. </li></ul><ul><li>Phenotypic variations influenced by environment limited in range by genes </li></ul><ul><li>Genotypic variations are stable not influenced by environment. </li></ul><ul><li>T.V.Rao MD </li></ul>
  28. 28. Principles of Genotypic variations <ul><li>Mutations </li></ul><ul><li>Genotypic by transfer of genes </li></ul><ul><li>Transformation </li></ul><ul><li>Transduction </li></ul><ul><li>(Lysogenic conversion) </li></ul><ul><li>Conjugation </li></ul>
  29. 29. Mutations in Bacteria <ul><li>Bacteria Multiply by asexual binary fission </li></ul><ul><li>Altered Nucleotide sequence in expresses new or </li></ul><ul><li>altered characteristics </li></ul><ul><li>Selective value to the organism </li></ul><ul><li>Evolutionary value </li></ul><ul><li>Acquires Antibiotic resistance grows in body without inhibition </li></ul><ul><li>Become a prominent organism </li></ul><ul><li>Phenotypic variation occurs when genes changes in response to the environment but reversible. </li></ul><ul><li>T.V.Rao MD </li></ul>
  30. 30. Mutations <ul><li>Mutation is a Random, Undirected, Heritable variation </li></ul><ul><li>Caused by alteration in the Nucleotide sequence at some point of DNA which can occur due to </li></ul><ul><li>Addition </li></ul><ul><li>Deletion </li></ul><ul><li>Substitution </li></ul><ul><li>of one or more bases </li></ul>
  31. 31. Mutations can occur in any sequence,inveitable, useful for Survival
  32. 32. Multiple Mutations <ul><li>Causes extensive chromosomal rearrangement </li></ul><ul><li>Missense mutation -Triplet code is acted so as to specify an Aminoacid different from that normally located at particular position in the protein </li></ul><ul><li>Nonsense mutation - Deletion of nucleotide within a gene may cause premature polypeptide chain termination by nonsense codon </li></ul><ul><li>Tran version is Substitution of purine for pyramidine or vice versa in the base pairing </li></ul>
  33. 33. Mutations <ul><li>Supressor Mutation is reversal of mutant phenotype by another mutation at a point of DNA distant from that of original mutation. </li></ul><ul><li>All genes are susceptible for mutations, but all mutations are not expressed </li></ul><ul><li>Lethal mutation is harmful destroy the vital functions </li></ul>
  34. 34. Mutations <ul><li>Conditional Lethal mutant may be Live under certain conditions </li></ul><ul><li>Common example is temperature ( its ) mutant </li></ul><ul><li>Temp sensitive ( ts) mutant lives at 35 0 c but not at 39 0 c </li></ul><ul><li>Each gene undergoes mutation at a fixed frequency. </li></ul><ul><li>Bacteria undergo mutations at 10 -4 - to 10 -10 </li></ul><ul><li>Tutomerisim T – A is replaced by G - A </li></ul>
  35. 35. Mutagenic Agents <ul><li>U V rays </li></ul><ul><li>Alkyl ting agents </li></ul><ul><li>Arcidine Dyes </li></ul>
  36. 36. GENE TRANSFER Occurs by Complex Mechanisims
  37. 37. Transformation of Genetic material ( Gene Transfer ) <ul><li>Different Mechanisms </li></ul><ul><li>Transformation </li></ul><ul><li>Transduction </li></ul><ul><li>Conjugation </li></ul>
  38. 38. What is Transformation <ul><li>Transformation is defined as transfer of Genetic information through the activity of DNA </li></ul><ul><li>Griffith experiment </li></ul><ul><li>Mice injected with Live non capsulated ( R ) Pneumococci </li></ul><ul><li>with heat killed capsulated (S) Pneumococci </li></ul><ul><li>Lead to death of Mice with isolation of Live capsulated Pneumococci </li></ul><ul><li>It means that some factor from Dead pneumococci transferred to live non pathogenic Pneumococci </li></ul><ul><li>Avery, McCleod, Mc Cartny in 1944 identified to be DNA </li></ul>
  39. 39. Griffith Phenomenon
  40. 40. Conjugation Laderberg - Tatum <ul><li>A process by which a Donor cell or male cell makes contact with another cell, the recipient or Female cell. </li></ul><ul><li>DNA is directly transferable </li></ul><ul><li>Plasmid Carry genetic information necessary for conjugation to occur. </li></ul><ul><li>Only cell that contain such plasmids can act as donor. the cell lacking a corresponding plasmid act as recipient. </li></ul><ul><li>Requires direct contact between donor and recipient </li></ul><ul><li>T.V.Rao MD </li></ul>
  41. 41. Conjugation - Transferring genes with plasmids <ul><li>Plasmids mediating conjugation carry genes coding for properties, of 1-2 microns long protein appendage termed Pilus on the Donor cell </li></ul>
  42. 42. Conjugation
  43. 43. Pilus helps Conjugation <ul><li>Different types of Pilus are specified by different types of plasmids and can help in aid of plasmid classification. </li></ul><ul><li>Only one strand of circular DNA of the plasmid nicked upon at a specific site and passed into a recipient. </li></ul><ul><li>Spread to all other cells. </li></ul>
  44. 44. F factor <ul><li>Transfer factor that contains the genetic information necessary for synthesis of Sex Pilus and for self transfer without any other identifiable genetic materials such as drug resistance </li></ul><ul><li>T.V.Rao MD </li></ul>
  45. 45. F factor helps transformation <ul><li>F + called as Donor bacteria can transform </li></ul><ul><li>F - into F + cell </li></ul><ul><li>Can be Episomes able to exist in some cells in the integrated state in the donor cell chromosome </li></ul><ul><li>Can transform chromosomal genes to recruitment with high frequency are known as Hfr cells </li></ul><ul><li>Conversion of F + cells into Hfr state is reversible. </li></ul><ul><li>F factor incorporates some chromosomal genes and is called as F’ </li></ul><ul><li>Sexduction The process of transfer of host genes through F’ factor </li></ul>
  46. 46. Transduction <ul><li>Transduction is defined as transfer of portion of DNA from one bacteria to another by Bacteriophages, is known as Transduction </li></ul><ul><li>T.V.Rao MD </li></ul>
  47. 47. Bacteriophages <ul><li>Are viruses that parasitize bacteria and consists of Nucleic acid core and a protein coat </li></ul><ul><li>A phage particle may have at its core besides its own nucleic acid and a segment of the Host DNA </li></ul>
  48. 48. DNA transfer through Bacteriophages <ul><li>When the Phage particle infects another bacteria DNA transfer is effected and the recipient cell acquires new characters coded by donor DNA </li></ul>
  49. 49. Types of DNA transfer through Bacteriophages
  50. 50. Transduction <ul><li>Generalized involve any segment of DNA </li></ul><ul><li>Restricted when specific Bacteriophages traduces only a particular genetic trait. </li></ul><ul><li>Transduction effects Plasmids ,and Episomes </li></ul><ul><li>Plasmid transfer induces Penicillin resistance in Staphylococcus </li></ul><ul><li>Helps Genetic mapping, also in eukaryotic cell </li></ul><ul><li>Helps Genetic Engineering </li></ul><ul><li>T.V.Rao MD </li></ul>
  51. 51. Transduction Types <ul><li>Two types of Transduction </li></ul><ul><li>1 Lytic and 2 Lysogenic </li></ul><ul><li>1 Virulent or Lytic cycle after large number of progeny are built up inside the host bacterium ruptures and phages are released </li></ul>
  52. 52. Transduction Lysogeny <ul><li>Bacteria called as lysogenic bacterium, in lysogenic bacteria prophages have an additional segment of bacterial chromosome </li></ul><ul><li>Codes for new characteristics </li></ul><ul><li>Influences susceptibility for Bacteriophages </li></ul><ul><li>Gains new antigen characters </li></ul><ul><li>T.V.Rao MD </li></ul>
  53. 53. Lysogenicity creates new characters <ul><li>Eg - Lysogenic conversion in Diphtheria bacilli which acquires toxigenicity by lysogenization with phage beta </li></ul><ul><li>Elimination of phage for toxigenic strain renders nontoxigenic </li></ul><ul><li>T.V.Rao MD </li></ul>
  54. 54. Colicinogenic ( Col ) Factor <ul><li>Coli form Bacteria produce Colicins </li></ul><ul><li>Colicins are lethal to other Enterobactericiae </li></ul><ul><li>Pyocins produce by Psedumonoas </li></ul><ul><li>Diptherocins produced by C.diptheria </li></ul><ul><li>Plamid transmits col factor leads to self transfer of chromosomal segments </li></ul><ul><li>T.V.Rao MD </li></ul>
  55. 55. Resistance Transfer Factor RTF <ul><li>Plasmids – helps to spread multiple drug resistance </li></ul><ul><li>Discovered in 1959 Japan </li></ul><ul><li>Infections caused due to Shigella spread resistance to following Antibiotics </li></ul><ul><li>Sulphonamides </li></ul><ul><li>Streptomycin </li></ul><ul><li>Choramphenicol, </li></ul><ul><li>Tetracycline </li></ul>
  56. 56. RTF <ul><li>Shigella + E.coli excreted in the stool resistant to several drugs in vivo and vitro </li></ul><ul><li>Plasmid mediated –transmitted by Conjugation </li></ul><ul><li>Episomes spread the resistance </li></ul>
  57. 57. Sequence of RTF transmission
  58. 58. Hfr cell conjugating a Normal cell
  59. 59. Composition of RTF <ul><li>Plasmid consists of two components </li></ul><ul><li>A transfer factor RT, helps conjugational transfer and resistant determinants ( r ) to each of the several drugs </li></ul><ul><li>RTF + r determinants are known as R factor </li></ul>
  60. 60. R factor <ul><li>R factor can contain several determinants as many as 8 or > 8 drugs </li></ul><ul><li>Guide the cell for production of Enterotoxins too </li></ul><ul><li>But R factors can be inhibited by </li></ul><ul><li>Bile salts </li></ul><ul><li>R factors can be transferred to animals </li></ul>
  61. 61. Genesis of R factors <ul><li>In discriminate use of Antibiotics in vetenary Medicine has increased the spread of R factors to Human </li></ul><ul><li>Addition of Antibiotics to Animal feeds to be prohibited. </li></ul>
  62. 62. Genetic Mechanisms of Drug Resistance <ul><li>Bacteria acquire drug resistance through several Mechanisms </li></ul><ul><li>Mutations </li></ul><ul><li>Genetic transfer </li></ul><ul><li>Transformation, </li></ul><ul><li>Transduction </li></ul><ul><li>Conjugation </li></ul><ul><li>Several Biochemical Mechanisms </li></ul><ul><li>Decreasing permeability of drugs, </li></ul><ul><li>Attaining alternative pathways </li></ul><ul><li>Produce enzymes and inactivate drugs </li></ul>
  63. 63. Genetic Mechanisms in Bacteria helps to spread the Infectious diseases
  64. 64. Mutations <ul><li>Mutatations can be </li></ul><ul><li>1 Stepwise mutation as in Penicillin use </li></ul><ul><li>2 One step mutation </li></ul><ul><li>Streptomycin use </li></ul><ul><li>May show low resistance or High resistance </li></ul><ul><li>If tuberculosis is treated with sole drug as of Only Steptomycin some resistant mutants appear and replaces senstive bacteria in due course </li></ul><ul><li>so the occurance of MDR - TB </li></ul>
  65. 65. Other Mechanisms <ul><li>Use of Penicillin created resistant Staphylococcus by transduction </li></ul><ul><li>R factors created resistance to several drugs, caused increased virulence </li></ul><ul><li>Spread to several humans and animals </li></ul><ul><li>Best option- To restrict use of </li></ul><ul><li>Antibiotics </li></ul>
  66. 66. Transposable Genetic Elements <ul><li>Structurally / Genetically – Discrete sequence of DNA – Move around in a cut and paste manner between Chromosomal and Extrachromosomal DNA molecules within cells. </li></ul><ul><li>Called as Transposons _ Jumping Genes </li></ul><ul><li>Genetic transfer due to Transposition </li></ul><ul><li>Small Transposons 1 – 2 Kb </li></ul><ul><li>Not self replicating and depend on Plasmid or Chromosome for replication. </li></ul><ul><li>A chunk of DNA is added by Transposons. </li></ul>
  67. 67. Transposons and R factor <ul><li>R forms may have evolved as a collection of Transposons </li></ul><ul><li>Each carrying Genes that confers resistance to one or several Antibiotics </li></ul><ul><li>Seen in Plasmids, </li></ul><ul><li>Microorganisms </li></ul><ul><li>Animals </li></ul><ul><li>Laboratory Manipulations are called as Genetic Engineering </li></ul>
  68. 68. Molecular Genetics <ul><li>Analysis and manipulation of DNA using Biochemical and Microbiological techniques </li></ul>
  69. 69. Genetic Engineering <ul><li>Under standing Molecular genetics in Biochemistry fuels genetic Engineering </li></ul><ul><li>Recombinant DNA (rDNA) techniques changed the ideals of Medicine </li></ul><ul><li>Genetic Engineering await many surprises? </li></ul>
  70. 70. Genetic Engineering <ul><li>Isolation of Genes coding for any desired protein from Microorganism or from cell of higher life forms including human beings and their introduction into a suitable microorganism in which genes would function directing the production of specific proteins </li></ul>
  71. 71. Genetic Engineering changing the Diagnostic and Therapeutic Protocols in MEDICINE
  72. 72. Research on Gene transfer shapes the future of Science
  73. 73. Genitically Engineered Products <ul><li>Can prepare desired protein in pure form in economic way </li></ul><ul><li>Somatostatin </li></ul><ul><li>Commercial preparations pf </li></ul><ul><li>Cloned Human Insulin </li></ul><ul><li>Interferons </li></ul><ul><li>Hepatitis B vaccine </li></ul>
  74. 74. Restriction Endonucleases <ul><li>A restriction enzyme (or restriction endonuclease ) is an enzyme that cuts double-stranded DNA . The enzyme makes two incisions, one through each of the sugar-phosphate backbones (i.e., each strand) of the double helix without damaging the nitrogenous bases . They work with cutting up foreign DNA, a process calle </li></ul>
  75. 75. Restriction Endonucleases Made the advances in Genetic Engineering
  76. 76. DNA Probes <ul><li>There are Radioactive </li></ul><ul><li>Biotinylated otherwise labelled copies united single stranded DNA </li></ul><ul><li>Contains 20 -25 nucleotides </li></ul><ul><li>Helps detection of Homology DNA by Hybridisation. </li></ul><ul><li>Helps Diagnosis of Infectious Diseases </li></ul><ul><li>Minute quantities of DNA can be detected. </li></ul>
  77. 77. Blotting Techniques <ul><li>Drug fragments obtained by restriction enzyme digestion on separation Gel can be transferred to Nitrocellulose or nylon membranes </li></ul><ul><li>Several methods </li></ul><ul><li>1 Southern blotting </li></ul><ul><li>2 Northern Blotting </li></ul><ul><li>3 Western blotting </li></ul>
  78. 78. Western Blotting <ul><li>In Western Blot Protein ( Antigen ) mixture is separated by SDS ( Sodium dodecyl sulfate – polyacrylamide gel electrophoresis ) Blotted on to Nitro cellulose strips and identified by radio labeled or enzyme labelled antibodies as probes </li></ul>
  79. 79. Western Blot to confirm HIV Infections made land mark Diagnostic tool <ul><li>Western Blot testing is confirmatory test for diagnosis of HIV/AIDS </li></ul><ul><li>Identifies antibodies directed against different antigens in pathogen </li></ul><ul><li>Surface, </li></ul><ul><li>Core </li></ul><ul><li>RT antigen </li></ul>
  80. 80. Polymerase chain reaction Kary B Mullis 1983 <ul><li>Rapid </li></ul><ul><li>Automatic amplification of specific DNA sequences </li></ul><ul><li>Nobel prize winning Technology 1993 </li></ul>
  81. 81. PCR -Sequences <ul><li>PCR consists of several cycles of sequential DNA replication where the products of first cycle becomes the template for the Next </li></ul><ul><li>It makes available abundant quantities of specific DNA sequences starting </li></ul>
  82. 82. Genetic Mapping <ul><li>Genetic sequences for Bacteriophages and virus </li></ul><ul><li>Genetic mapping is done most of the Human Genes </li></ul>
  83. 83. Newer Understanding on GENES
  84. 84. Human Genome Project
  85. 85. Human Genome Project <ul><li>C ompleted in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health. During the early years of the HGP, the Wellcome Trust (U.K.) became a major partner; additional contributions came from Japan, France, Germany, China, and others </li></ul>
  86. 86. Genetics are Complex - Leading the birth of BIOINFORMATICS
  87. 87. Genes Evolved and made us Men What NEXT ?
  88. 88. Are We Playing with Genes in the Right Direction ?
  89. 89. Understanding of human Genome is Changing the Future of Medicine
  90. 90. Created for Basic Teaching to Medical students Dr.T.V.Rao. MD email tvraodoctor2000@yahoo.co.in
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