In E. coli cells, when lactose is absent from the environment,
A. no b-galactosidase, lactose permease, andgalactosidetransacetylas are made.
B. polycistronic mRNA levels would be very high.
C. trace amounts of b-galactosidase, lactose permease, and galactosidetransacetylase are made.
D. the lac operon is induced.
E. large amounts of b-galactosidase, lactose permease, and galactosidetransacetylase are made.
Answer: C
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Adult T-cell leukemia is thought to be caused by
A. parvoviruses. B. herpesviruses. C. picornaviruses. D. retroviruses.
The M protein of group A streptococci inhibits:
A. antibody binding. B. phagocytosis. C. T-cell apoptosis. D. lymphocyte proliferation.
Why does removing an overripe, mushy apple from a container of otherwise good apples help preserve the good apples?
A) Chemicals in the overripe apple stimulate the conversion of sugar to starch in the good apples. B) Ethylene production in the good apples is inhibited by the lack of ethylene production in the overripe apple. C) Gibberellins help preserve the good apples. D) The overripe apple makes ethylene gas, which can cause the good apples to ripen more quickly than usual. E) The production of cytokinins is inhibited in the remaining good apples.
Which description(s) correspond to class Prokaryote in order to test your understanding of the characteristics of prokaryotes, eukaryotes, and viruses.
> Must be viewed with an electron microscope > Acellular particle > Size range: 10-200nm > Cell type that lacks a nucleus > Contains a nucleus and other membrane-bound organelles > Size range: 1-10?m