What does the hydrolysis of a purine base from the deoxyribose-phosphate backbone leave behind?
A) an apurinic site
B) a modified base
C) a double-strand break
D) a mutation
E) a deletion
A) an apurinic site
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One effect of auxin, which triggers the elongation of cells, is to affect cell walls by increasing their
A. permeability. B. plasticity. C. stiffness. D. thickness. E. water solubility.
Amanatin, a toxin from the death cap poisonous mushroom, inhibits RNA polymerase, so it
A. stops initiation, elongation, and termination stages of transcription. B. reverses the direction of RNA polymerase action, tearing apart partially formed proteins. C. prevents the initiator tRNA from beginning translation. D. incorrectly places the release factor protein on mRNA and terminates translation. E. disables any introns from being produced, to complete the protein structures.
One way that antibiotic-resistant strains of bacteria arise is that patients do not follow the instructions for taking the drug. In a typical scenario, a drug may be prescribed for a week, but the patient may stop taking it after 2 to 3 days if they start to feel better. Then when the infection flares up again, they take the rest of their dose. Why would this scenario lead to drug resistance?
A. The first round of treatment gives the bacteria a chance to learn how to metabolize the drug. B. A patient begins to develop resistance to the drug. C. The body clears the drug faster, once it is exposed a second time. D. The first round of treatment does not kill the most resistant bacteria, which then increase in number. E. The first round of treatment suppresses the immune system, making the patient more susceptible to other infections.
The binding of a plant hormone to its receptor typically induces ____
a. an increase in membrane permeability b. an enzyme-substrate cascade c. an inhibition of protein synthesis d. a change in gene expression e. increased DNA replication activity