Which of the following statements concerning enzymes is FALSE?
A. They are usually, but not always, proteins.
B. They always function best at 37°C.
C. They can be denatured if the pH of their environment is too high or too low.
D. They form a temporary intermediate compound with a substrate.
E. They can be used to catalyze a chemical reaction over and over again.
Answer: B
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In spite of their heterogeneity, steroid hormones:
A. have the same effect on different types of cells. B. bind to cell-surface receptors. C. bind intracellular receptors to form complexes that migrate to the nucleus. D. are hydrophilic small molecules that bind to intracellular receptors. E. facilitate the initiation of translation by ribosomes.
Clostridium difficile is inoculated to two different media. Media X is a rich, nutritious complex growth media. Media Y is a minimal synthetic media containing only the minimum ingredients needed for growth. After 48 hours, which media do you expect to contain a greater proportion of endospores? Explain your reasoning.
b. What is the counterstain used in acid-fast staining? c. Why can safranin not be used as the counterstain in acid-fast staining? d. In your own words, explain why some bacterial species produce endospores. What are their purpose? e. Name two genera of bacteria that produce endospores. f. What is the primary stain in Schaeffer-Fulton endospore staining? g. What is the counterstain in Schaeffer-Fulton endospore staining? h. What is the purpose of steam during Schaeffer-Fulton endospore staining? What do you expect would happen if steam were not used?
An otherwise normal yeast cell with a diploid number of 32 chromosomes does not undergo
replication prior to M phase. What would be the result after mitosis and cytokinesis, assuming that all processes after S phase occur properly?
What will be an ideal response?In which type of vessel might you find a valve to assist blood flow?
a. artery
b. arteriole c. capillary d. venule e. vein