What alleles are maintained in area's where warfarin is used as a selective agent?
Both warfarin resistant and sensitive alleles.
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Which has the best rate of survival without warfarin? Why?
rr - The dominant R allele confers a requirement for vitamin K which is often unsustainable, especially in RR rats.
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What kind of advantage is this?
Heterozygote
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Antibiotic resistance - Why are antibiotics over used in farming?
Farm animals are reared indoor to increase growth. Greater risk of disease in crowded conditions. Broad spectrum antibiotics are added to food to try and prevent outbreaks of disease.
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How do some bacteria become resistant?
Mutations that occur randomly in bacterial populations that confer an advantage
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How does the initial resistant bacteria become a whole population?
The antibiotics are a selection pressure that favour the resistant bacteria. The non-resistant bacteria die allows the resistant bacteria the opportunity to reproduce (binary fission) and pass on the gene.
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Example of antibiotic resistance.
Bacteria produce the enzyme penicillinase.
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How else, other than reproduction, can antibiotic resistance be transmitted?
Conjugation - Resistance passed via plasmids between species
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What problem can this cause?
A disease causing organism can become resistant to an antibiotic before said antibiotic is used against them
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