Q: Tropomyosin is a type of what, that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin? Read this paragraph and choose the correct option from the provided answers: Tropomyosin is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. Tropomyosin binds to troponin to form a troponin-tropomyosin complex. The troponintropomyosin complex prevents the myosin "heads" from binding to the active sites on the actin microfilaments. Troponin also has a binding site for Ca++ ions. To initiate muscle contraction, tropomyosin has to expose the myosin-binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments. The first step in the process of contraction is for Ca++ to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands. This allows the myosin heads to bind to these exposed binding sites and form cross-bridges. The thin filaments are then pulled by the myosin heads to slide past the thick filaments toward the center of the sarcomere. But each head can only pull a very short distance before it has reached its limit and must be "re-cocked" before it can pull again, a step that requires ATP. Choices: - enzyme - bacteria - amine - protein A:
protein
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Q: Through which artery does blood enter the kidneys? Read this paragraph and choose the correct option from the provided answers: Blood enters the kidney through the renal artery, which branches into capillaries. When blood passes through capillaries of the glomerulus of a nephron, blood pressure forces some of the water and dissolved substances in the blood to cross the capillary walls into Bowman's capsule. Choices: - thoracic artery - jugular - cerebral artery - renal artery A:
renal artery
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Q: Unlike eukaryotic cells, dna and rna synthesis in prokaryotic cells occurs together with synthesis of what? Read this paragraph and choose the correct option from the provided answers: ART CONNECTION QUESTIONS 1. Figure 14.10 In eukaryotic cells, DNA and RNA synthesis occur in a separate compartment from protein synthesis. In prokaryotic cells, both processes occur together. What advantages might there be to separating the processes? What advantages might there be to having them occur together? 2. Figure 14.14 You isolate a cell strain in which the joining together of Okazaki fragments is impaired and. Choices: - membrane - fruit - mutation - protein A:
protein
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Q: In earthworms, the skin serves as what type of organ? Read this paragraph and choose the correct option from the provided answers: Choices: - kidney - reproductive - excretory - respiratory A:
respiratory
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