AP Bio Cell Communication

See changes in signal transduction pathway quiz 1 The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein? A The intracellular concentration of glycogen will increase. B The intracellular concentration of activated protein kinase A will increase. C The intracellular concentration of cyclic AMP will increase. D The intracellular concentration of glucose-1-phosphate will increase.

A

See changes in signal transduction pathway quiz 3 Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. Figure 1. Model of signal transduction cascade incorporating protein A A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation? A Production of activated molecule 1 will stop, but production of activated molecules 2 and 3 will continue. B The molecule that normally binds to protein A will no longer attach, deactivating the cellular response. C The molecule that normally binds to protein A will not enter the cell, thus no cellular response will occur. D Since protein A is embedded in the membrane, the mutation will be silent and not affect the cellular response.

B

Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch's ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell's nucleus and alter the expression of specific genes. Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway? A Delta transmits a chemical signal to all the cells of a developing embryo. B Delta allows the cells of a developing embryo to communicate without making direct contact. C Delta restricts cell communication to short distances within a developing embryo. D Delta determines which cells in a developing embryo express the gene that encodes the Notch protein.

C

Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances? A The proteins receive electrical signals from nerve cells. B The proteins leave the cell and travel in the bloodstream to other cells. C The proteins interact directly with proteins on the surfaces of other cells. D The proteins bind to molecules secreted by cells located in other parts of the body.

C

Ethylene causes fruits to ripen. In a signaling pathway, receptors activate transcription factors, which ultimately leads to ripening. Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to ripening of fruit? A Ethylene is a simple gaseous molecule, which makes it easily detected by receptors. B Fruit will ripen in closed containers without exposure to air. C Ethylene synthesis is under both positive and negative feedback regulation. D Loss-of-function mutations in ethylene receptors result in changes to the ripening process.

D

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher's claim? A Epinephrine is a signaling molecule that binds to a transmembrane protein. B The G protein in the epinephrine signaling pathway consists of three different subunits. C Phosphorylase kinase catalyzes the hydrolysis of ATP. D Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

D

See q5 Researchers investigating the regulation of neurotransmitter release from presynaptic neurons proposed a model (Figure 1) in which CDK5 , a protein expressed in axon terminals, inhibits the movement of synaptic vesicles to the presynaptic membrane. To test their model, the researchers used a modified version of green fluorescent protein (GFP*) . In slightly alkaline conditions, GFP* exhibits a bright green fluorescence. In acidic conditions, GFP* exhibits no fluorescence. Using standard techniques, the gene encoding GFP* is easily introduced into living cells. By engineering the expression of GFP* in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. Previous experiments indicate that CDK5 is active only when attached to a protein called p35 . Which of the following best predicts how p35 might play a role in regulating neuron function? Attachment of p35 to synaptic vesicles results in increased synaptic activity. Reabsorption of p35 from the synaptic cleft results in increased synaptic activity. Elevated intracellular levels of p35 result in increased synaptic activity. Degradation of p35 results in increased synaptic activity.

Degradation of p35 results in increased synaptic activity

See q4 Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells A researcher claims that the epinephrine signaling pathway controls a catabolic process in muscle cells. Which of the following statements best helps justify the researcher's claim?

Glycogen phosphorylase catalyzes the conversion of glycogen to glucose-1-phosphate.

In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMP inside the cell. The cyclic AMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway? It acts as a second messenger that helps relay and amplify the signal within the cell. It acts as a receptor that carries the signal from outside the cell to inside the cell. It acts as a signaling molecule that passes the signal from the cell to other cells. It acts as a channel protein that transmits the signal across the cell's nuclear membrane.

It acts as a second messenger that helps relay and amplify the signal within the cell.

See q6 Steroid hormones, such as testosterone, pass through the plasma membrane and bind to an intracellular protein, as shown in the diagram below. The hormone-receptor complex then enters the nucleus, where it interacts with DNA to promote transcription of a specific gene. Based on the information presented, which of the following will also occur in response to steroid signaling? DNA replication will increase as a result of the binding of the hormone-receptor complex to the DNA . Histone protein synthesis will increase because histones maintain the DNA in an optimal conformation for chromosome assembly. Ribosome production will increase because ribosomes are specific for the mRNA with which they bind during translation. Production of a specific mRNA will increase as a result of the binding of the hormone-receptor complex to the DNA .

Production of a specific mRNA will increase as a result of the binding of the hormone-receptor complex to the DNA

In flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following? Small, water-soluble molecules Membrane-bound organelles Condensed, duplicated chromosomes Branched polysaccharides

Small, water-soluble molecules

See changes in signal transduction pathway quiz 2 Glucocorticoids are steroid hormones that control cellular responses through several different signaling pathways. One of the signaling pathways involves the glucocorticoid receptor, an intracellular protein that is activated by binding to a glucocorticoid molecule. A simplified model of the glucocorticoid receptor signaling pathway is represented in Figure 1. Figure 1. A simplified model of the glucocorticoid receptor signaling pathway Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function? A The transduction of the glucocorticoid signal across the plasma membrane will be blocked. B The glucocorticoid receptor will remain associated with the accessory proteins. C The rate of diffusion of glucocorticoid molecules into the cell will increase. D The concentration of glucocorticoid receptors inside the nucleus will increase.

The glucocorticoid receptor will remain associated with the accessory proteins.

Vertebrate immune responses involve communication over short and long distances. Which of the following statements best helps explain how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances? The proteins interact directly with proteins on the surfaces of other cells. The proteins leave the cell and travel in the bloodstream to other cells. The proteins receive electrical signals from nerve cells. The proteins bind to molecules secreted by cells located in other parts of the body.

The proteins interact directly with proteins on the surfaces of other cells.

See q8 The coagulation cascade controls blood clot formation in response to blood vessel injury. Thrombin is an enzyme that plays a key role in regulating the coagulation cascade. A simplified model of thrombin's role in regulating the coagulation cascade is represented in Figure 1. Figure 1. A simplified model of thrombin's role in regulating the coagulation cascade Argatroban is a competitive inhibitor of thrombin. Which of the following effects on the coagulation cascade is most likely to result from inhibiting thrombin activity with argatroban? The rate of fibrin formation will decrease. Thrombin will be converted to prothrombin. The activation of clotting factors will be blocked. The rate of blood clot formation will increase.

The rate of fibrin formation will decrease

A student claims that the Y chromosome contains the sex-determining region gene, known as the SRY gene, which causes male fetuses to develop testes. Which of the following provides correct information about cell signaling that supports the claim? A The SRY gene is found only in tissues of the developing gonads. B The SRY gene produces a protein that binds to specific regions of DNA in certain tissues, which affects the development of these tissues. C The SRY gene produces an RNA segment that is exported from specific cells and targets the developing gonads. D The SRY gene produces a protein that deletes portions of the X chromosome in males so that male characteristics can develop.

B

Notch is a receptor protein displayed on the surface of certain cells in developing fruit fly embryos. Notch's ligand is a membrane-bound protein called Delta that is displayed on the surface of adjacent cells. When Notch is activated by its ligand, the intracellular tail of the Notch protein becomes separated from the rest of the protein. This allows the intracellular tail to move to the cell's nucleus and alter the expression of specific genes. Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway? Delta transmits a chemical signal to all the cells of a developing embryo. Delta restricts cell communication to short distances by requiring direct cell-to-cell contact for activation of the Notch signaling pathway. Delta allows the cells of a developing embryo to communicate without making direct contact. Delta determines which cells in a developing embryo express the gene that encodes the Notch protein.

Delta restricts cell communication to short distances by requiring direct cell-to-cell contact for activation of the Notch signaling pathway.

See q1 The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells Based on Figure 1, which of the following statements are correct in describing the epinephrine signaling pathway? Two answers It involves the opening and closing of ion channels. It involves a second messenger that helps relay and amplify the signal within the cell. It involves the deactivation of Adenylyl cyclase.. It involves enzymes activating other enzymes.

It involves a second messenger that helps relay and amplify the signal within the cell. It involves enzymes activating other enzymes.

See q11 Figure 1 shows a model of a signal transduction cascade, initiated by the binding of a ligand to the transmembrane receptor protein A. Figure 1. Model of signal transduction cascade incorporating protein A A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A produced by the cell. Which of the following predictions is the most likely consequence of the mutation? The molecule that normally binds to protein A will not enter the cell, thus no cellular response will occur. Production of activated molecule 1 will stop, but production of activated molecules 2 and 3 will continue. Since protein A is embedded in the membrane, the mutation will be silent and not affect the cellular response. Since the specified mutation changes the shape of the ligand-binding site, the cascade will not be activated, and the cell will not respond to the presence of the ligand.

Since the specified mutation changes the shape of the ligand-binding site, the cascade will not be activated, and the cell will not respond to the presence of the ligand.

Type 1 diabetes results from the destruction of insulin-producing cells in the pancreas. Individuals with type 1 diabetes produce insufficient amounts of insulin, a hormone that regulates the concentration of glucose in the blood. Which of the following best explains how treatment with a drug that stimulates the production of insulin receptors on target cells will affect the insulin signaling pathway in an individual with type 1 diabetes? The drug will restore the function of the signaling pathway because insulin levels will return to normal. The drug will have little or no effect on the signaling pathway because insulin receptors will not be allowed to enter the cells. The drug will restore the function of the signaling pathway because nonpancreatic cells will begin to produce insulin receptors. The drug will have little or no effect on the signaling pathway because the receptors will not be activated in the absence of insulin.

The drug will have little or no effect on the signaling pathway because the receptors will not be activated in the absence of insulin.

See q2 Figure 1. A simplified model of the glucocorticoid receptor signaling pathway Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function? Two answers. The rate of diffusion of glucocorticoid molecules into the cell will increase. The glucocorticoid receptor will remain in its inactive state in the cytosol. The glucocorticoid receptor will remain associated with the accessory proteins. The transduction of the glucocorticoid signal across the plasma membrane will be blocked.

The glucocorticoid receptor will remain in its inactive state in the cytosol. The glucocorticoid receptor will remain associated with the accessory proteins.

See q 13 The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor. A simplified model of the epinephrine signaling pathway is represented in Figure 1. Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells. Which of the following outcomes will most likely result from the irreversible binding of GDP to the G protein? The intracellular concentration of cyclic AMP will increase. The intracellular concentration of glucose-1-phosphate will increase. The intracellular concentration of activated protein kinase A will increase. The intracellular concentration of glycogen will increase.

The intracellular concentration of glycogen will increase.