During calcium chloride transformation of bacteria, during which step does plasmid DNA enter the bacterial cells?
A) Brief incubation with CaCl2 on ice
B) Brief electric shock following treatment with CaCl2
C) Selection on antibiotic plates
D) Brief incubation at 42°C
E) None of these choices
D
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Bacteria, insects, and plants use carbohydrates to build structures. Which of the following is true of structural carbohydrates?
A) Different types of pentose monomers form the basis of all carbohydrate-based structures. B) Structural carbohydrates show a high degree of branching. C) All structural carbohydrates are made from the same monomer, ?-glucose. D) Structural carbohydrates are long strands, which are chemically linked into a network.
Plants maintain higher levels of phytochrome at their growing tips where phytochrome plays important roles in growth responses to light. Phytochrome levels are also high in areas of the plant that are "greening." What does this suggest about the role of phytochrome in these "greening" zones?
A. Phytochrome is facilitating the transcription and translation of photosynthesis related proteins. B. Phytochrome is absorbing green wavelengths of light. C. Phytochrome is facilitating the migration of chlorophyll pigments from other areas of the plant. D. In these areas, phytochrome is the first step in the electron transport chain of photosynthesis.
Water is sometimes called the 21st amino acid because of its importance in defining protein structure. The basis for this is the so-called hydrophobic effect. Which of the following BEST describes the hydrophobic effect?
A) all of the choices are correct B) Polar regions of the protein are repelled by water, driving them to the interior of the protein C) water and the protein arrange themselves so that the nonpolar surface in contact with water is maximized D) Non-polar regions of the protein are repelled by water, driving them to the interior of the molecule
An agricultural worker experiences difficulty breathing which becomes progressively worse. Tests show inflammation and damage of the lung tissue, but IgE antibodies and granulocytes are in the normal ranges. With which disorder of the immune system are these signs and symptoms consistent?
A. allergic reaction B. type III (immune complex-mediated) hypersensitivity C. type IV (delayed) hypersensitivity D. autoimmunity E. acquired immunodeficiency