You cut some sheep DNA and some plasmid DNA with the same restriction enzyme. The plasmid contains an AmpR gene and a lacZ gene. You mix together the fragments of sheep DNA and the linearized plasmid. You transform bacteria with your mixture, and plate the bacterial cells on growth media containing the antibiotic ampicillin and X-gal (the substrate of beta-galactosidase). You need to pick some bacterial colonies that contain recombinant plasmids. Which colonies do you choose?
A. Any colony; if they grow on the media they are recombinant.
B. The blue colonies; any cells containing eukaryotic (sheep) DNA will be blue.
C. The white colonies; only cells that contain a recombinant plasmid will be white.
D. The large colonies; large colonies are more resistant to the antiobiotic and thus more likely to contain a recombinant plasmid.
E. Any colony, all colonies will contain plasmids; it requires additional testing to determine if the plasmid is recombinant.
Answer: C
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Scientists develop a chemical that binds to molecules that make quorum sensing possible, rendering those molecules non-functional. If this chemical is incorporated into a mouthwash, how would it affect the community of bacteria that cause dental plaque?
A. Their negative effects would be reduced because they will no longer be able to produce mucilage and stick to teeth. B. Their negative effects would be reduced because they will no longer be able to produce the acid that damages teeth. C. Their negative effects would be increased because it will cause them to produce mucilage, allowing them to stick to teeth. D. Their negative effects would be increased because it will cause them to produce the acid that damages teeth. E. It would have no effect because they will still be able to form a biofilm and secrete the acid that damages teeth.
Which of the following does NOT have an exoskeleton?
a. lobsters b. spiders c. insects d. earthworms e. centipedes
Describe the mechanism(s) used by bacteria and eukaryotes for transcription termination
What will be an ideal response?
In an experiment described in a chemistry lab book, the directions state that after mixing two chemicals (A and B) and waiting 5 minutes that A will be oxidized. This means that:
A. chemical A has gained energy in the form of heat from chemical B. B. chemical A has lost energy in the form of heat to chemical B. C. chemical A has lost electrons to chemical B. D. chemical A has reacted with oxygen. E. chemical A has gained electrons from chemical B.