The stomach is an extremely hostile place. What protects it from digesting itself?
What will be an ideal response?
The mucus produced by its lining is protective and alkaline, so it prevents the hydrochloric acid from damaging the stomach. The lining cells actually make and release an inactive protein called pepsinogen rather than active pepsin directly. The cells of the stomach lining are rapidly replaced. Finally, gastric juices are normally released only when food is present, and the food will dilute the juices and reduce the chance of damage.
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A ____ individual is always part of a testcross
a. heterozygous b. homozygous recessive c. homozygous dominant d. self-fertilized e. dihybrid
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
A) PDGF B) MPF C) cyclin D) Cdk
The leading cause of preventable death in the United States is cardiovascular disease. Which of the following are lifestyle modifications that would lower a person's risk of CVD?
A. lose weight B. lower fat intake C. not smoking D. All of the choices are means of lowering risk for CVD.
A stomach cell is producing pepsin, an enzyme that hydrolyzes proteins. Which of the following events suggests that gene expression of pepsin has been turned off in the cell?
A) The pepsin protein is folded properly in the cytoplasm. B) The chromosome with the pepsin gene is tightly coiled. C) The pepsin mRNA leaves the nucleus and enters the cytoplasm. D) Activators and RNA polymerases are abundant in the nucleus.