Exam 11: Cell Communication

In an experiment to track the movement of growth factor molecules from secretion to the point of receptor binding in a particular species of mammal, a student found a 20-fold reduction in mm traveled when in the presence of an adrenal hormone. This is in part attributable to which of the following?

The termination phase of cell signaling requires which of the following?

The human population's life expectancy has increased significantly but seems to have an upper limit. Which of the following might be described as an ecological consequence of passing that upper limit by regulating cell death?

Which of the following is a likely explanation of why natural selection favored the evolution of signals for sexual reproduction?

Use this information to answer the following questions. Affinity chromatography is a method that can be used to purify cell-surface receptors, while they retain their hormone-binding ability. A ligand (hormone) for a receptor of interest is chemically linked to polystyrene beads. A solubilized preparation of membrane proteins is passed over a column containing these beads. Only the receptor binds to the beads. -When an excess of the ligand (hormone)is poured through the column after the receptor binding step, what do you expect will occur?

Which of the following is true of transcription factors?

Apoptosis involves all but which of the following?

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of

Which of the following is true for the signaling system in an animal cell that lacks the ability to produce GTP?

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

Use this description to answer the following questions. A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. -If you wish to design an experiment to block the G protein-coupled receptor interaction, the block would preferentially affect which of the following?

Which of the following statements is true of signal molecules?

Use this information to respond to the following questions. Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma. -The description above illustrates which of the following?

In C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?

Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell?

In which of the following ways could signal transduction most probably be explored in research to treat cancer?

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

Since steroid receptors are located intracellularly, which of the following is true?

Testosterone functions inside a cell by

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?