Bio 180 Exam 5 BYUI Questions and Answers Already Passed

Bio 180 Exam 5 BYUI Questions and Answers Already Passed Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because: Intracellular receptors are present only in target cells. Which type of receptor is most associated with metabolism, cell growth, and cell division? Tyrosine kinase receptors Which type of receptor is a dimer that when bound to the proper ligand autophosphorylates? Tyrosine kinase receptors A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following? A decrease in transcriptional activity of certain genes. Binding of a signaling molecule to which type of receptor leads directly to a change in distribution of ions on opposite sides of the membrane? Ligand-gated ion channel Which type of signaling is long-distance signaling mediated by chemicals released into the blood? Endocrine signaling The dissociation constant (Kd) for a receptor is the ligand concentration that results in ____ percent of the receptors being bound. 50 The dissociation constants for epinephrine and norepinephrine on beta2-adrenergic receptors are 0.50 and 0.10 nM, respectively. Which of these ligands is more efficient in activating the beta2-receptors? Norepinephrine An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? Phospholipase C What explains the increased concentration of Ca2+ in the ER? Calcium ions are actively imported from the cytoplasm into the ER. 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? Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding. Where does IP3 come from? A membrane phospholipid. Cytokinesis typically occurs during: Telophase How many chromatids are there in somatic cells during G2 phase? 92 Which of the following statements is true regarding the difference between mitosis and meiosis? Following mitosis, each daughter cell is diploid, while the cells resulting from meiosis are haploid. Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect: The formation of the mitotic spindle. During which phase of mitosis does the nuclear envelope fragment? Prometaphase The sodium-potassium pump is considered electrogenic because: It pumps three cations out of the cell while pumping only two cations into the cell. In general, carrier proteins can carry out: Passive and Active Which of the following is not one of the types of gated ion channels? Gradient-gated channels If a membrane protein in an animal cell is involved in the cotransport of glucose and sodium ions into the cell, which of the following is most likely true? A substance that blocked sodium ions from binding to the cotransport protein would also block the transport of glucose. Which of the following statements is true for the sodium-potassium pump? It pumps potassium into the cell while pumping sodium out of the cell. MPF is shut off by: destroying cyclin What does cdk do? It phosphorylates other proteins. A malignant tumor: A type of cancer At the M phase checkpoint, the complex allows for what to occur? Separase enzyme cleaves cohesins and allows chromatids to separate. Which of the following characteristics allows a cancer cell to metastasize? Anchorage independence Acquired migratory abilities Continuous proliferation Which of the following categories of endocytosis is primarily driven by the protein clathrin? Pinocytosis Receptor-mediated Endocytosis Which of the following is the least specific with respect to what is bought into the cell? Pinocytosis Which of the following processes involves actin? phagocytosis Which of the following processes would be utilized to release insulin from the beta cells of the pancreas? Exocytosis A certain channel protein in the cell membrane is equally permeable to both Na+ and K+. Na+ concentrations are high on the outside of the cell (which is positive), while K+ concentrations are high on the inside of the cell (which is negative). Assuming equal concentration gradients for both Na+ and K+, which of the following statements is true regarding the movement of these ions through this channel? More Na+ ions will be transported. Which of the following would require facilitated diffusion in order to cross the cell membrane? Glucose Water Carbon dioxide Sodium All of the above A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body fluids, distilled water (equal to the volume of blood lost) is transferred directly into one of his veins. What will be the most probable result of this transfusion? The patient's red blood cells will swell because the blood fluid is hypotonic. It is observed that when placed in a solution a cell shrinks. What can we say about the solution? the solution is hypertonic Water passes quickly through cell membranes because: It moves through aquaporins in the membrane. Which of the following processes would enable a cell to take in large quantities of a specific molecules such as LDL cholesterol? Phagocytosis Receptor mediated endocytosis Which of the following categories of endocytosis is regulated by cellular receptors? Phagocytosis Receptor mediated endocytosis Which of the following processes involves clathrin? Pinocytosis Exocytosis Receptor mediated endocytosis Which of the following requires ATP? Exocytosis Phagocytosis Pinocytosis All of the above Which of the following categories of endocytosis is primarily driven by the protein clathrin? Pinocytosis Receptor-mediated Endocytosis Which of the following membrane activities require energy from ATP hydrolysis? Na+ ions moving out of the cell. Glucose diffuses very slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells? Facilitated difussion Which of the following types of transport can use the electrochemical gradient of sodium to move a solute against its concentration gradient? Secondary Active transport Which type of signaling involves release of signal by a cell that acts on cells in the local environment? Paracrine Signaling One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? Receptor tyrosine kinases With respect to question on G Protein coupled receptors, the coupled G protein most likely interacts with this receptor: At the loop between H5 and H6. Which of the following is a correct association? GTPase activity and hydrolysis of GTP to GDP and Pi. Insulin binds to its receptor on the liver causing the liver to store glucose as glycogen. Regulate enzyme activity. Testosterone binds it receptor in a skeletal muscle cell which leads to this muscle growing larger (hypertrophy) is response to exertion. Regulate gene transcription. Cells surrounding the site of an infection release chemical signals which are "sensed" by white blood cells and allows them to migrate toward the site of infection. Activate movement of cytoskeleton. A cell surface receptor on a fibroblast cell receives a signal from a growth factor causing the cell to produce a cyclin which leads to its progression through the cell cycle regulate gene transcription Which of the following most accurately describes how a signal is propagated by a phosphorylation cascade? In a series, kinases use ATP to transfer a phosphate to protein substrates. Protein phosphorylation is commonly involved with all of the following EXCEPT? Activation of G protein-coupled receptors. The function of phosphatases in signal transduction is best described as to: Inactivate protein kinases and turn off the signal transduction. Why do neurons and some other specialized cells divide infrequently? They have been shunted into G0. Under normal conditions, crowded cells stop dividing. What is this phenomenon called? density-dependent inhibition What could happen to the target cells in an animal that lack receptors for local regulators? They would not be able to multiply in response to growth factors from nearby cells. What causes the decrease in the amount of cyclin at a specific point in the cell cycle? Its destruction by a process initiated by the activity of its complex with a cyclin. Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? Chromosomally abnormal cells can still go through cell cycle checkpoints. Which statement best describes why oxygen gas moves through the lungs and into red blood cells? Oxygen diffuses through membranes from high concentration to low concentration. Solution A has more dissolved particles than Solution B. Which of the following statements is true regarding these two solutions? Solution A is hyperosmotic with respect to Solution B. What is the force that drives diffusion? The concentration gradient for the solute. The microtubule-organizing center of the animal cell contains a pair of centrioles. It resides just outside of the nucleus. It is also known as the: centrosome Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? centrosome During which phase of mitosis do the chromosomes align in the center of the cell? Metaphase A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of eight picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2? 16:16 At which phase are centrioles beginning to move apart in animal cells? Prophase If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound: That increases phosphodiesterase activity. Which of the following is true for the signaling system in an animal cell that lacks the ability to produce GTP? It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. Lipid-soluble signal molecules, such as testosterone, cross the membranes of all cells but affect only target cells because: Intracellular receptors are present only in target cells. A drug is developed that prevents the movement of transport vesicles from the rough ER to the Golgi. Which of the following processes would be most affected when this drug is administered? Cytokinesis in plant cells. During which phase of mitosis do the chromatids become chromosomes? Telophase The standard Kool Aid recipe calls for 1 cup of sugar dissolved in 2 quarts of water. But you like your Kool Aid more sour, so you only add 14 cup sugar. Which of the following statements is true? The original Kool Aid is hyperosmotic to your sour Kool Aid Which of the following is true about the passage of water across a cell membrane? Because water is polar, it cannot easily cross the cell membrane. Plant cells do best in: hypotonic solution Which of the following types of transport can use the electrochemical gradient of sodium to move a solute against its concentration gradient? secondary active transport Which of the following enzymes removes phosphate from proteins? phosphatase Adenylyl cyclase has the opposite effect of which of the following? Phosphodiesterase Epinephrine excites some tissues and inhibits others. What is the best explanation for these observations? The transduction pathways differ in the different tissues. Which of the following molecules involved in signaling are considered second messengers? cAMP, IP3,CA2+,Diacylglycerol Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of: cAMP A hallmark of cancer cells is anchorage independence—the ability to grow on a surface that does not resemble the cell's native microenvironment. Along with the availability of growth factors and the density of cells surrounding the cancer cells, anchorage independence in normal cells is linked to the key environmental checkpoint in the cell cycle. As such, which of the following is true? Signal transduction pathways from properly adhered cells would likely result in the transcription of cyclins. A particular cyclin, called "cyclin E," forms a complex with Cdk 2 (cyclin-dependent kinase 2). This complex is important for the progression of the cell from G1 into the S phase of the cell cycle. Which of the following statements is correct? The amount of free cyclin E is highest during G1. Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? CDK 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? Cyclin