Resistance 5.8

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How has human influence affected the evolution of resistance? Example.
Created new selection pressures. Warfarin resistance in rats. Antibiotic resistance in bacteria
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Warfarin resistance in rats - Alleles (3)
RR - Homozygous resistance Rr - Heterozygous resistance rr - Homozygous no resistance
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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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Other cards in this set

Card 2

Front

Warfarin resistance in rats - Alleles (3)

Back

RR - Homozygous resistance Rr - Heterozygous resistance rr - Homozygous no resistance

Card 3

Front

What alleles are maintained in area's where warfarin is used as a selective agent?

Back

Preview of the front of card 3

Card 4

Front

Which has the best rate of survival without warfarin? Why?

Back

Preview of the front of card 4

Card 5

Front

What kind of advantage is this?

Back

Preview of the front of card 5
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