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33 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Gene Transfer in Bacteria occus on two levels
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Horizontal-Transfer of genes from one bacterium to another in the same generation.
Vertical-transfer of genes from parent bacterial cells to daughter bacterial cells |
up and down
left and right |
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3 Mechanisms of Horzontal gene transfer
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1. Transformation
2. Transduction 3. Conjugation |
all thee common in Gram + and Gram -
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Most prolific producer of antibiotics. Lives in the harsh soil environment. More than hlf of our antibiotics come from this bacteria.
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Streptomyces
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Antibiotic streptomycin
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Naked DNA in the environment is transferred to recipient bacteria
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Transformation
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Process for Transformation
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Bacteria cell die and releases DNA into its environment, it breaks up into smaller pieces (20 genes each). Some of the DNA is taken up by the nearby bacteria, the DNA is then incorporated into the bacterial chromosome
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Transpormation and transduction occur naturally and are most commin in both
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Gram + and Gram - bacterial cells
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Bacteria cells must have the ability to take up DNA. What is this called
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Competent
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Bacteria usually become this during the end of the log phase growth.
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Transfer of bacterial genes from one cell to another by means of a bacterial virus is called bacteriophage
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Transduction
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Phage means "to eat"
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What is the process of transduction
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The bacteriophage sits down on teh bacterial cell and injects itself into the bacterial cell and sucks up the DNA with it's mid section. The transferred bacterial DNA becomes integrated into the host bacterial chromosome
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THe transfer of DNA that requires CONTACT between teh donar cell ad the recipient cell, involving the sex pilus that connects the two cells.
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Conjugation
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This is as close as it gets to sexual reproduciton. Probably the most important method of gene transfer
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An extrachormosomal piesce of double-stranded DNA in bacteria that replicate independently
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Plasmids
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The genes that are transferred via conjugation are often contained on...
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F plasmids are fertility plasmids that contain genes necessary for
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1. formation of the sex pilus
2. Transfer of the plasmid |
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A bacterium that contains an F plasmid is designated ___ and if the bacterium does not contain an F plasmid, it is designated ____
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F+
F- |
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Transfer of Plasmid takes place in four steps
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1. F+ donor and F- crecipient bacterial cells come into contact with sex pili and bind to receptor sites on the recipient cell then are pulled close together.
The F plasmid is cleaved by an enxime to form a single stranded end A single strand of the plasmid enters the F- cell. THis takes about 2 min. The other cell remains in the donor cell. complementary strands of DNA are synthesized to make the single DNA strands in the donor recipient cells functional double-stranded DNA plasmids F- cell becomes F+ |
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Happens when F plasmid becomes incorporated ino the bacterial chromosome prior to transfer. The donor bacterial cell becomes known as Hfr (high frequency of rcombination) cell.
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Chromosome Transfer
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Chromosome Transfer has the same process as plasmid transfer yet with 2 major differences
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1. Most recipient cells remain F-
2. Recipient cells receive some chromosomal DNA integrates into the recipient bacterial chromosome |
Examples of how plasmids convey important traits and characteristics in baceria are:
1. Resistance genes R-Plasmids 2.(Ti)Tumor Inducing in plants-Agrobacterium tumefaciens 3. Nitrogen fixation in plants- Rhizobium converts N2 into NH3 infects roots and produces nodules 4. Antibiotic Synthesis- Streptomyces 5. Toxin Production- Bacillus anthracis |
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Play a very important role in gene transfer in bacteria
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Transposons or Jumping Genes
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Gene transfer porfides new genetic information and new combinations of genes in bacteria, giving them new traits and charachtersitics allows bacteria to survive and adapt to changing environments. Aids the process of evolution via natural selection
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Plant that can establish a symbiotic relationship with Rhizobium bactera are plants called
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Legumes
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________ ______ in any organism increases chances of survival
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Genetic Diversity
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Who made the 1st major attempt to classify bacteria; grouped bacteria according to shape:
Sherical Short Rod Long Rod Spiral |
Ferdinand Cohn
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Not adequate- did not acount for all kinds of bacteria
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Who made the 2nd attempt to classify bacteria based on their physiological or biochemical properties such as Metabolism, Nutrients, and biproducts
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Jensen
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He felt that the relatedness among bacteria could be determined by comparing gene products or necleotide sequences. He assumed that all prokaryotes were basically similar- conjugation makes this difficult
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Roger Stranier
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He compared sequences of bases in Ribosomal RNA. It became clear from the results of these comparisons that prokaryotes could be divided into t major groups:
1. Archaea common to Eukarya 2. Bacteria |
Carl Woese
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The Science that studies organisms in order to arrange them into groups
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Taxonomy
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Taxonomy encompasses 3 areas; what are they?
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Identification- process of characterizing organisms
Classification- process of arranging organisms into similar or related groups Nomenclature- system of assigning names to organisms |
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Strategies used in identification
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1. Microspic examination- Cell shape, arrangement, staining
2. Cultural Characteristics- colony size, shape morphology, color 3. bichemical tests - physiology and metabolism 4. Necleic acid analysis |
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Classification Scheme for E. coli.
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Domain- Bacteria
Kingdom- Eubacteria division- Proteobacter Class- Grammaproteo bacteria Order- Enterbacteriales Family- Enterobacteriaceac Genus- Escherichia Species- coli |
When members fo the same species of baceria have characteristics that differentiate whem from one another they are referred to as diffent strains for example E. coli O157:H7
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E. coli O157:H7
O number refers to antigen on lipopolysaccharide H number refers to antigen on flagella Strain is pathogenic because toxins code for bacteriophage DNA that has become incorporated into the bacterial chromosome this process is called |
Lysogenic Conversion
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Methods used to characterize strain differences
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1. biochemical typing
2. Serological typing 3. Genomic typing 4. Phage Typing 5. Antibiograms |
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The reference used by most microbiologist and bacteriologists to find information on specific bacteria is
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Bergey's Manual of Systematic Bacteriology
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What is Phylogeny
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Evelutionary relatedness
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goal of all toxonomists
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He worked with 2 different strains of diplococcus pneumoniae and mice to determine resistant antibiotics.
Avirulent-Rough colony Virulent-smooth colony this caused disease and he called the phenominon Transformation |
Frederick Griffith
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Bacteria are named according to International Code for the Nomenclature of Bacteria.
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Nomenclature
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reflects a characteristic of the bacterium
may include the name of a prominent researcher |
