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24 Cards in this Set
- Front
- Back
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Genetics
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Study of what genes are
how they carry information (deoxyribonucleotide sequence) how information is expressed (transcription and translation) how genes are replicated (DNA synthesis) |
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Gene
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segment of DNA that encodes a functional product, usually a protein
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Genome
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all of the genetic material in a cell
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Genomics
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molecular study of genomes
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Genotype
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genes of an organism
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Phenotype
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expression of the genes
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Flow of Genetic Information
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Mutation
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Change in the genetic material (as little as one deoxyribonucleotide)
Mutations may be neutral, beneficial, or harmful |
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Mutagen:
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agent that causes mutations
UV light and chemicals that react with DNA |
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Spontaneous mutations:
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occur in the absence of a mutagen
Frequency [1 mutation per million cells to 1 mutation per billion cells] Ex:Neisseria gonorrhoeae penr (spontaneous) |
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Change in a Population of Bacteria
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Colony: all identically identical cells? no
Mutation (change in existing gene) Recombination (pick up new genes) |
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Recombination
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exchange of genes between two DNA molecules
Crossing over occurs when two chromosomes break and rejoin ex: Genetic recombination Crossing over Donor and recipient cell DNA |
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Transformation
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uptake fragments of DNA in environment
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Conjugation
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cell to cell transfer of DNA involves contact
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Transduction
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cell to cell transfer of DNA via virus
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Recombination Scenarios
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1.Transformation
2.Conjugation 3.Transduction significance is bacteria acquire new virulence factors and antibiotic resistance genes Ex: gene for capsule production gene for penicillin resistance |
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Transformation Experiment
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Transformation Mechanism
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Fredrick Griffith (1928)
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(Transformation)
Streptococcus pneumoniae virulent or S strain (smooth colonies) avirulent or R strain (rough colonies) transformation factor Competent (recipient strain) |
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Oswald Avery (1944)
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demonstrated the transformation factor was DNA
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Conjugation
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direct cell to cell contact
conjugative plasmid present in donor cell plasmid genes code for pili copy of plasmid transfers to recipient cell donor cells called F+ recipient cells (F-) become F+ intergenic transfer : Escherichia, Salmonella, Shigella, Serratia |
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Conjugative plasmid
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(Plasmids)
Carries genes for (F Factors) pili and transfer of the plasmid |
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Dissimilation plasmids
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(Plasmids)
Encode enzymes for catabolism of unusual compounds |
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R factors
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(Plasmids)
Encode antibiotic resistance |
