Microbial Genetics Genetics the science of heredity Genome the genetic information in the cell Genomics the sequencing and molecular characterization of genomes Gregor Mendel Grew pea plants ID: 1044474
Download Presentation The PPT/PDF document "Unit 3c Microbial Genetics" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
1. Unit 3cMicrobial Genetics
2. Microbial GeneticsGenetics: the science of heredityGenome: the genetic information in the cellGenomics: the sequencing and molecular characterization of genomesGregor MendelGrew pea plants from 1856-1863.Genetics: the science of heredityGenome: the genetic information in the cellGenomics: the sequencing and molecular characterization of genomes
3. A cell’s genome includesChromosomes and _________Chromosomes are structures containing the DNAPlasmids
4. A bacterium has a single circular chromosome consisting of a single circular molecule of DNA
5. Plasmids (review)small loops of extrachromosomal DNA in bacteriaoften carry genes for virulence, bacteriocins (toxic proteins that kill other bacteria) or drug resistance (codes for enzymes that inactivate certain drugs or toxic substances)can recombine into new combinationstransmitted from organism to organism
6. Eukaryotic DNA sites
7. DNAFig. 2.16Nucleotides
8. “Genes”Segments of DNA (except in some viruses, in which they are made of RNA) that code for functional productsDNA
9. each gene could be several thousand or more base pairs long.E. coli approximately 4,300 genes (4.6 million base pairsHumans have approximately 20,000 to 25,000 genes.Based on Human Genome Project
10. Nucleic AcidsDNA and RNADNA: deoxyribonucleic acidRNA: ribonucleic acidMessenger RNA (mRNA)Ribosomal RNA (rRNA)Transfer RNA (tRNA)Nucleotides are the structural units of nucleic acids
11. Nucleotides (Review)a nucleic acid is a long chain of nucleotideseach nucleotide has 3 parts:a 5-carbon ________ribose in RNAdeoxyribose in DNAA __________ groupa ___________ baseSugarPhosphateNitrogenous
12. One nucleotide
13. RNA nucleotide with uracil
14. Nucleic acidsRNA: usually a single chain of nucleotides (may be double in viruses)
15. DNA: usually a double chain of nucleotides (may be single in viruses)2 kinds of base pairs:PurinesPyrimidines
16. Nucleotides Complementary Base Pair Nucleotide bases bind to each other in a specific manner = complementary base pairing.Specific purines complementary base pair with specific pyrimidines.Complementarybase pairing inDNA
17. DNADouble helix of James Watson and Frances Crick
18. Review of Proteins:long chains of amino acids: hundreds of amino acids in complex three-dimensional arrangementsthere are 20 naturally occurring kinds of amino acidseach amino acid in a protein must be exactly the right kind of amino acid or it will be a different protein
19. the function of a gene is to determine the sequence of the amino acids to make a specific protein
20. The genetic codeThe set of rules that determine how a nucleotide sequence is converted into the amino acid sequencealong a mRNA, groups of 3 consecutive nucleotides is a codon, the genetic code for one amino acid e. g. —P—R—P—R—P—R— l l l U A C64 possible mRNA codons for 20 amino acidsthere can be up to 6 codons that specify the same amino acida few codons specify NO amino acid (start or stop codons),signal the end of the protein molecule’s synthesis
21. The genetic code
22. An overview of genetic flow ….figure 8.2
23. 1) DNA replicationreproduction of a molecule basis of continuity of lifemolecule “unzips” along the hydrogen bondseach half attracts the nucleotides needed to recreate the other halfif successful, both new molecules are identical to the original and to each other
24. DNA Polymerase – Enzyme that connects each nucleotide togetherDNA Ligase – Enzyme that connects sections of DNA togetherDNA ReplicationOkazaki Fragments5’5’3’3’Lagging Strand Leading Strand3’5’
25. Figure 8.6
26. DNA replication precedes cell division
27. 2) Transcription= production of RNA by DNADNA produces several kinds of RNAmessenger-RNA (m-RNA) carries the genetic code for a protein out from the chromosome to the ribosomes transfer-RNA (t-RNA) carries individual amino acids to the messenger RNA which puts them in the proper sequenceribosomal-RNA (r-RNA) links up the amino acids to form a protein
28. Translation= protein synthesis, translating the genetic code into a specific protein chain of amino acids
29. Fig. 8.10Simultaneoustranscription andtranslation inbacteria
30.
31. Becomes mRNA (messenger RNA) – this has the code for how to build a protein_________________________Connects RNA nucleotides together (like DNA polymerase)RNA Polymerase
32. Codon- A section of three nucleotides in a row that code for an amino acidtRNA – transfer RNA anticodon & amino acid
33.
34. Polypeptide Chain – all the amino acids who together
35.
36.
37. MutationsCan be negative, neutral, or positive!defined as a change in the base sequence of DNAcan involve one or more nucleotidesthe source of new genes (such as virulence or drug resistance)about one mutation per million replicated genescauses:errors in DNA replicationradiationmutagenic chemicals
38. The electromagnetic spectrum: effective wave lengths:a. ultraviolet radiationdamages DNAoptimum wave length: 260 nmpoor penetrating ability
39. Ames Test uses bacteria as carcinogenindicators (figure 8.22)Many known mutagens have been found to be carcinogens
40. Genetic RecombinationThe exchange of genes between 2 DNA molecules to form new combinations of genes on a chromosome.Vertical gene transferGenes are passed from an organism to its offspringHorizontal gene transferBetween bacteria of the same generation!Donor cell to recipient cell = recombinant
41. An overview of genetic flow ….figure 8.2
42. Bacterial gene transfersBacteria have a number of forms of recombination:_________________________________ConjugationTransformationTransduction
43. Bacterial conjugation (DNA transferred through a mating process)2 bacteria connected by a tube calledthe sex pilusF = fertility factor (ability to mate)F+ is equal to being male (one thatgrows the sex pilus)F– is equal to being a femaleDNA passes through the sex pilusfrom the F+ to the F–usually just the F factor, but sometimesother genes are carried along F– becomes F+
44. Figure 8.24: Griffith’s Transformation Experiment
45. Transduction: Transduction: host DNA carried from cell to cell by virusFigure 8.28
46. BiotechnologyRestriction Enzymes – enzymes found in bacteria that cut DNA at specific sequences.
47. …Since 1978!
48. Cotton Plants with Bacillus gene inserted (left)
49. Bioremediation
50. Pharmaceuticals
51. Figure 9.1
52. DNA in diagnosis4. Nucleic acid hybridization Basis of DNA probesShort segments of ssDNA that are complementary to the desired geneComplementary strands of known DNA separated by heatOne side marked with fluorescent dyeDNA of unknown bacteria separated by heatWill hybridize with fluorescent strand of known DNA if same kind. After rinsing away unbound DNA, a fluorescent DNA double strand will remainCan hunt for complementary DNA within a massive amount of material, such as food
53. DNA-DNA hybridization (fig. 10.15)
54. DNA probe to detect Salmonella Why useE. coli ?Easilygrown &researchersare familiarwith its geneticsFigure 10.16
55. DNA probe, continued
56. DNA probe, continued
57. DNA Chips (figure 10.17)An array of DNA probes arranged in a DNA chip can be used to identify pathogens