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20 Cards in this Set
- Front
- Back
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Define: gene
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A gene is a segment of DNA, a sequence of nucleotides that codes for a functional product, usually a protein.
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Compare bacterial chromosomes and plasmids.
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-Bacteria have a single circular chromosome consisting of a single circular molecule of DNA with associated proteins.
-Plasmids are self-replicating circular molecules of DNA carrying genes that are not usually essential for the cells survival. |
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List the several types of plasmids.
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Plasmids include conjugative, dissimilation, plasmids carrying genes for toxins or bacteriocins, and resistance factors.
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Define: mutation
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A mutation is a change in the nitrogenous base sequence of DNA; that change causes a change in the product coded for by the mutual gene.
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What causes mutations?
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The causes:
-Spontaneous mutations occur without the presence of any mutagen at the rate of one in a billion; mutation occurs in a gene at the rate of one in a million. -Chemicals cause mutagens. -Radiation: UV or ionizing radiation. |
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Compare genetic mutation and recombination.
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-Genetic mutation is change in nucleotide sequence.
-Recombination is large pieces of DNA or whole genes recombining. |
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Compare vertical and horizontal gene transfer.
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-Vertical gene transfer occurs during reproduction when genes are passed from an organism (parent) to its offspring, aka "inheritance".
-Horizontal gene transfer in bacteria involves a portion of the cells DNA being transferred from donor to recipient, aka "non-inheritance". |
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Define: Transformation
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Transformation- (1)the process in which genes are transferred from one bacterium to another as "naked" DNA in solution. (2)the changing of a normal cell into a cancerous cell.
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Define: Conjugation
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Conjugation-(plasmid sharing) the transfer of genetic material from one cell to another involving cell-to-cell contact between living cells.
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Define: Transduction
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Transduction- the transfer of DNA from one cell to another by a bacteriophage. In generalized transduction, any bacterial gene can be transferred.
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Define: Transposon
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Transposon- a small piece of DNA that can move from one DNA molecule to another; aka jumping genes that transpose around.
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Compare the mechanisms of horizontal gene transfer and recombination.
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Genetic recombination, the rearrangement of genes from separate groups of genes, usually involves DNA from different organisms, it contributes to genetic diversity. In crossing over, genes from two chromosomes are recombined into one chromosome containing some genes from each original chromosome. Horizontal gene transfer in bacteria involves a portion of the cells DNA being transferred from donor to recipient.
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Describe conjugation in bacteria.
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This process requires contact between living cells. One type of genetic donor is an F+; recipient cells are F-. F cells contain plasmids called F factor(F=fertility); these are transferred to the F- cells during conjugation.
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Give an example of mutations that affect disease and disease control.
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HIV/Influenza have new strains due to mutation, making it hard for the Immune System to catch up.
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Give an example of resistance factor and virulence factors that are carried on plasmids.
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R-Factor (R100)- half of the plasmid has genes for transfer (conjugation). The other half of the plasmid might have some ABX resistors, i.e., chloramphenicol, mercury, sulfonamide, streptomycin, and tetracycline.
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Give an example of virulence factors that apparently have been transferred by transduction.
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-Capsules - reproduction.
-Toxins: Staphylococcus aeureus: Exfoliative toxin (Scalded Skin Syndrome) Enterotoxigenic E. Coli toxin (Traveler's diarrhea) Clostridium tetani: neurotoxin produces sustained muscle contraction. Bacillis anthracis: Plasmid (1) [3 toxins, 1 capsule] need all to be a toxin. |
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What is natural selection?
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Genetic mutation and recombination provide a diveristy of organisms, and the process of natural selection allows the growth of those best adapted to a given environment.
-Adaptation to local conditions; shift in local conditions survive and produce offspring. |
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Explain how you would find an antibiotic-resistant mutant by direct selection and how you would find an ABX sensitive mutant by indirect selection.
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A mutant is isolated by direct selection b/c it grows on a particular medium. The colonies on an ABX containing medium can be identified as resistant to that ABX.
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Bacteria can acquire ABX resistance by:
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-mutation
-insertion of transposons -acquiring plasmids |
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Plasmids differ from transposons
because: |
plasmids are self-replicated outside the chromosome.
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