Physiology Concepts Quiz
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Questions and Answers

Which component of the cell membrane is responsible for linking with another molecule, such as choline or ethanolamine?

  • Glycerophospholipids
  • Phosphate head (correct)
  • Fatty acid tail
  • Glycerol backbone

    • What is the usual length of the fatty acid tail in the glycerophospholipids of the cell membrane?

  • 16-18 carbons (correct)
  • 20-22 carbons
  • 18-20 carbons
  • 14-16 carbons

    • Which type of membrane protein is involved in identifying foreign substances and initiating an immune response?

  • Receptor protein (correct)
  • Enzymatic protein
  • Carrier protein
  • Channel protein

    • Which cellular structure is primarily responsible for maintaining cell shape and providing mechanical support?

    <p>Intermediate filaments</p> Signup and view all the answers

    Which lipid component of the cell membrane is important for stabilizing membrane fluidity and integrity?

    <p>Cholesterol</p> Signup and view all the answers

    Which cytoskeletal component is involved in intracellular transport, aiding in vesicle movement within the cell?

    <p>Microtubules</p> Signup and view all the answers

    Which function of the cell membrane involves regulating the passage of molecules into and out of the cell?

    <p>Transport</p> Signup and view all the answers

    Why are cell membranes considered semi-permeable?

    <p>Because they allow the passage of water but prevent the passage of many solutes.</p> Signup and view all the answers

    What is the role of aquaporins in the plasma membrane?

    <p>Enhancing high water conductance.</p> Signup and view all the answers

    How does the Na+/K+ ATPase prevent cell swelling?

    <p>By establishing a gradient of sodium and potassium across the membrane.</p> Signup and view all the answers

    What happens when ATP levels fall to 10% of normal levels in cells?

    <p>Cells start to swell.</p> Signup and view all the answers

    What do cell membranes rely on for important signaling and metabolic functions?

    <p>Concentration gradients.</p> Signup and view all the answers

    What is the primary function of the Na+/K+ ATPase transporter?

    <p>To regulate solute concentration and cell volume.</p> Signup and view all the answers

    Why is the plasma membrane impermeable to many solutes, especially larger ones?

    <p>Because large solutes cannot pass through the aquaporins due to their size.</p> Signup and view all the answers

    What type of process involves a protein moving a substance(s) across a membrane against a concentration gradient using ATP?

    <p>Active transport</p> Signup and view all the answers

    Which protein allows a substance to move across the membrane along its concentration gradient?

    <p>Aquaporins</p> Signup and view all the answers

    What is the primary driving force that moves Na+ into the cell according to the text?

    <p>High [Na+] in the extracellular fluid</p> Signup and view all the answers

    Which type of transport involves a protein carrier binding to a substance and transporting it across a membrane along its concentration gradient?

    <p>Facilitated transport</p> Signup and view all the answers

    What is the process called that transports two substances (X and Y) using the same protein?

    <p>Cotransport</p> Signup and view all the answers

    Which of the following proteins moves substances across the membrane against their concentration gradients?

    <p>Na+/K+ ATPase</p> Signup and view all the answers

    What type of transport involves a protein forming a channel that allows substances to move across the membrane along their concentration gradients?

    <p>Passive transport</p> Signup and view all the answers

    What is the main function of most receptors on the cell membrane, according to the text?

    <p>Binding to extracellular signals</p> Signup and view all the answers

    Which part of the receptor plays a role in amplifying the signal, as mentioned in the text?

    <p>Intracellular domain</p> Signup and view all the answers

    How does the cell decide whether to respond to a signal such as a hormone, according to the text?

    <p>By expressing the specific receptor</p> Signup and view all the answers

    Which type of proteins are mentioned in the text to have diverse functions like signaling and transport?

    <p>Membrane proteins</p> Signup and view all the answers

    In extracellular signaling, what is typically required for a cell to respond to a signal?

    <p>Expressing the specific receptor for the signal</p> Signup and view all the answers

    Which domain of the receptor extends through the lipid bilayer, as mentioned in the text?

    <p>Hydrophobic domain</p> Signup and view all the answers

    What is the primary role of hydrophobic domains in most cell membrane receptors?

    <p>Extending through the lipid bilayer</p> Signup and view all the answers

    What determines whether a cell responds to a growth factor or anti-growth signal?

    <p>Expression of specific receptor</p> Signup and view all the answers

    Which part of a typical extracellular signal plays a critical role in determining if a cell will respond?

    <p>Specific receptor expression</p> Signup and view all the answers

    What is the role of flippase in the translocation of phospholipids across the ER membrane?

    <p>Translocates phospholipids from the cytosolic side to the luminal side</p> Signup and view all the answers

    What component is necessary to help with the addition of head groups to phosphatidic acid?

    <p>Adenine</p> Signup and view all the answers

    Why can't newly made phospholipids spontaneously flip over to the luminal side of the ER membrane?

    <p>Because of the presence of specific enzymes</p> Signup and view all the answers

    What happens to pieces of sER membrane containing new phospholipids?

    <p>They bud off as vesicles and are inserted into the plasma membrane</p> Signup and view all the answers

    Which side of the ER membrane do flippases translocate phospholipids to?

    <p>Cytosolic side</p> Signup and view all the answers

    In the context of phospholipid translocation, what is the function of flippase?

    <p>Translocates lipids between membrane leaflets</p> Signup and view all the answers

    What is a key characteristic of the translocation process facilitated by flippase?

    <p>Specific directionality in lipid movement</p> Signup and view all the answers

    What role do vesicles play in the transportation of new phospholipids?

    <p>They insert new phospholipids into the plasma membrane</p> Signup and view all the answers

    What are the three main components of a phospholipid?

    <p>Hydrocarbon chain, Backbone, and Glycerol</p> Signup and view all the answers

    Which derivative is formed when both fatty acids are linked to the glycerol backbone with an ester link in a phospholipid?

    <p>Phosphatidate</p> Signup and view all the answers

    Why is phosphatidic acid referred to as a 'phosphate-alcohol head group'?

    <p>It has a phosphate group and an alcohol group in its structure</p> Signup and view all the answers

    Which component forms the backbone of sphingomyelin?

    <p>Ceramide</p> Signup and view all the answers

    What is the basic structure of a phospholipid?

    <p>Phosphatidate H</p> Signup and view all the answers

    Which are the three most common phosphoglycerides found in the cell membrane?

    <p>Phosphatidylethanolamine, Phosphatidylserine, Phosphatidylcholine</p> Signup and view all the answers

    What is formed when one fatty acid is linked to the glycerol backbone with an ester link and the other with an ether link?

    <p>Plasmalogen</p> Signup and view all the answers

    Which type of phospholipid is much more common in the cell membrane?

    <p>Phosphatidates</p> Signup and view all the answers

    What is the first step in phospholipid synthesis as described in the text?

    <p>Addition of two fatty acyl CoAs to glycerol-3-phosphate</p> Signup and view all the answers

    What is the common feature regarding the fatty acids attached at carbon positions 1 and 2 in phosphatidic acid?

    <p>C-1 is saturated and C-2 is unsaturated</p> Signup and view all the answers

    What occurs during step 3 of phospholipid synthesis?

    <p>Activation of a hydroxyl group by attachment of cytosine diphosphate (CDP)</p> Signup and view all the answers

    Which molecule is responsible for donating methyl groups in the conversion of phosphatidylethanolamine to phosphatidylcholine?

    <p>S-adenosylmethionine (SAM)</p> Signup and view all the answers

    What role does phosphatidylinositol primarily play in cell membranes according to the text?

    <p>Cell signaling</p> Signup and view all the answers

    Which type of phospholipid interconversion can occur in a reversible head-group exchange reaction?

    <p>Phosphatidylserine to phosphatidylethanolamine</p> Signup and view all the answers

    What happens when a eukaryotic cell adds CDP-headgroup to diacylglycerol during phospholipid synthesis?

    <p>Addition of a head group to the diacylglycerol</p> Signup and view all the answers

    'Methyl groups are donated by S-adenosylmethionine (SAM)' - Which process does this statement refer to?

    <p>&quot;Addition of 3 methyl groups&quot;</p> Signup and view all the answers

    Where does phospholipid synthesis primarily occur?

    <p>Smooth ER</p> Signup and view all the answers

    What is the first shared step between phospholipid synthesis and triacylglycerol synthesis?

    <p>Synthesis of glycerol backbone</p> Signup and view all the answers

    What molecule can glycerol-3-phosphate be derived from?

    <p>Dihydroxyacetone phosphate (DHAP)</p> Signup and view all the answers

    Which cellular structure is involved in the conversion of glycerol-3-phosphate from dihydroxyacetone phosphate (DHAP)?

    <p>Mitochondria</p> Signup and view all the answers

    What is the final step in phospholipid synthesis after the addition of the head group?

    <p>Exchange/modification of head group</p> Signup and view all the answers

    Which type of phospholipid is synthesized with ceramide backbone instead of glycerol?

    <p>Sphingomyelin</p> Signup and view all the answers

    What is the primary function of attachment of fatty acids to the glycerol backbone in phospholipid synthesis?

    <p>Facilitate transport across membranes</p> Signup and view all the answers

    Which cellular compartment is responsible for the initial steps of phospholipid synthesis?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    What is the step in phospholipid synthesis that differentiates it from triacylglycerol synthesis?

    <p>Exchange/modification of head group</p> Signup and view all the answers

    What happens to glycerophospholipids after the addition of head groups?

    <p>They undergo exchange or modification.</p> Signup and view all the answers

    What is the cellular location where cholesterol synthesis primarily occurs?

    <p>Endoplasmic reticulum</p> Signup and view all the answers

    Which organs significantly contribute to cholesterol synthesis within the body?

    <p>Liver and kidney</p> Signup and view all the answers

    What is the key regulatory enzyme involved in cholesterol synthesis?

    <p>HMG CoA reductase</p> Signup and view all the answers

    What is the main influence on HMG CoA reductase by insulin and glucagon?

    <p>Inhibition</p> Signup and view all the answers

    Which lipid component is found in large amounts in the cell membrane along with phospholipids?

    <p>Steroids</p> Signup and view all the answers

    How many fused rings does cholesterol contain in its structure?

    <p>Four</p> Signup and view all the answers

    What molecular group characterizes sterols like cholesterol?

    <p>Hydroxy group at C3</p> Signup and view all the answers

    Which molecule is involved in the inhibition of HMG CoA reductase by high intracellular levels of cholesterol?

    <p>Cholesterol esters</p> Signup and view all the answers

    How many acetyl CoA molecules are required to form squalene in cholesterol synthesis?

    <p>3</p> Signup and view all the answers

    Which enzyme catalyzes the rate-limiting step in the formation of Mevalonate?

    <p>HMG CoA reductase</p> Signup and view all the answers

    What is the intermediate compound formed by the condensation of 6 activated isoprene units?

    <p>Squalene</p> Signup and view all the answers

    Which step in cholesterol synthesis involves the conversion of mevalonate into activated isoprenes?

    <p>Step 2</p> Signup and view all the answers

    The cyclization of squalene into cholesterol occurs in which step of cholesterol synthesis?

    <p>Step 4</p> Signup and view all the answers

    What is the highly-regulated enzyme catalyzing the rate-limiting step of cholesterol synthesis?

    <p>HMG CoA reductase</p> Signup and view all the answers

    Which cellular organelle hosts HMG-CoA reductase, the main regulatory enzyme in cholesterol synthesis?

    <p>Smooth endoplasmic reticulum</p> Signup and view all the answers

    What inhibits HMG-CoA reductase by promoting its phosphorylation, thus inhibiting cholesterol synthesis?

    <p>Glucagon</p> Signup and view all the answers

    Which condition leads to the blockage of transcription of the HMG-CoA reductase gene?

    <p>High intracellular cholesterol levels</p> Signup and view all the answers

    How does insulin affect HMG-CoA reductase activity?

    <p>Promotes de-phosphorylation, activating the enzyme</p> Signup and view all the answers

    What happens to HMG-CoA reductase when it is in its inactive phosphorylated state?

    <p>It tends to remain inactive</p> Signup and view all the answers

    How does high intracellular cholesterol levels affect esterification of cholesterol?

    <p>Promotes esterification for storage in the cell</p> Signup and view all the answers

    What is the driving force for the flow of a substance from point A to point B in a system?

    <p>Energy gradient between point A and point B</p> Signup and view all the answers

    How is flow related to the size of the energy gradient between two points in a system?

    <p>Flow is directly related to the gradient size</p> Signup and view all the answers

    What type of law describes fluid flow in a system?

    <p>Poiseuille's law</p> Signup and view all the answers

    Which factor directly influences the amount of flow from point A to point B in a system?

    <p>Energy gradient between A and B</p> Signup and view all the answers

    What does every system have that resists the flow of a substance from one point to another?

    <p>Factors</p> Signup and view all the answers

    In the model of flow down gradients, what does point A represent?

    <p>Starting point</p> Signup and view all the answers

    What does Poiseuille's law describe in the context of a system?

    <p>Fluid flow</p> Signup and view all the answers

    What parameter causes gas or liquid to flow from point A to B in a tube?

    <p>Hydrostatic pressure</p> Signup and view all the answers

    Which law determines the rate of flow of a gas or liquid through a tube?

    <p>Pouiseuille's law</p> Signup and view all the answers

    What characteristics of the substance impacts its flow in a tube according to the text?

    <p>Viscosity of the fluid</p> Signup and view all the answers

    What does Poiseuille's law define in the context of fluid flow through a tube?

    <p>Volume of liquid passing through a tube per unit time</p> Signup and view all the answers

    Which process can drive the molecular flow of gases, water, and solutes as described in the text?

    <p>All of the above</p> Signup and view all the answers

    What major variable is determined by Fick's law and Ohm's law in relation to the movement of substances in the body?

    <p>Rate of diffusion</p> Signup and view all the answers

    What characteristics determine the movement of gases and fluids through vessels?

    <p>Physical and chemical properties of the gases and fluids</p> Signup and view all the answers

    What critical impact does physical structure have on the flow of substances in a tube?

    <p>Resistance to flow</p> Signup and view all the answers

    What does the Nernst equation primarily indicate?

    <p>Energy gradient for particle movement</p> Signup and view all the answers

    Why is the Nernst potential important in understanding ion movement across a membrane?

    <p>It influences the energy gradient for ion movement</p> Signup and view all the answers

    What aspect does the Nernst potential NOT account for when describing ion movement?

    <p>Current flow or resistance of the membrane</p> Signup and view all the answers

    In the context of Nernst potential, what does the negative voltage value signify?

    <p>Anions moving out of the cell</p> Signup and view all the answers

    Which factor determines whether sodium or potassium has an unequal distribution across the cell membrane?

    <p>Ratio of intracellular to extracellular concentrations</p> Signup and view all the answers

    What is the significance of understanding the Nernst potential in relation to ion movement?

    <p>Predicting ion movement direction based on voltage</p> Signup and view all the answers

    Why is knowing the Nernst potential crucial for understanding cellular physiology?

    <p>Balancing electrochemical gradients for ion transport</p> Signup and view all the answers

    What aspect of Robert’s medical history explains his foot swelling?

    <p>Decreased cardiac output and worsening blood supply</p> Signup and view all the answers

    What is the main cause of Robert's shortness of breath?

    <p>Decreased cardiac output</p> Signup and view all the answers

    How does Robert's foot swelling illustrate the physicochemical laws discussed in the pre-learning and lecture?

    <p>Starling's Law of Capillary Forces</p> Signup and view all the answers

    Why does blood 'back up' in the venous system in heart failure?

    <p>Worsened cardiac output from the ventricles</p> Signup and view all the answers

    Which condition primarily leads to impaired 'forward-flow' in heart failure patients?

    <p>Decreased cardiac output</p> Signup and view all the answers

    What happens to tissues with poor blood supply in heart failure?

    <p>They experience enhanced function</p> Signup and view all the answers

    How does the physiopathology of heart failure manifest physicochemical principles?

    <p>'Starling's Law of Capillary Forces' impacts fluid distribution</p> Signup and view all the answers

    Why does a neuron maintain a membrane potential close to the Nernst potential for potassium?

    <p>To ensure efficient signaling through action potentials</p> Signup and view all the answers

    What purpose does the unequal distribution of charge serve in living cells?

    <p>To regulate the transport of substances</p> Signup and view all the answers

    What role do selective transporters and channels play in establishing the membrane potential of living cells?

    <p>They facilitate the movement of specific ions to create an imbalance</p> Signup and view all the answers

    How do medications and pathologies impact the membrane potential of cells?

    <p>They can alter the membrane potential of different cell types</p> Signup and view all the answers

    Why doesn't a neuron's membrane potential match exactly with the equilibrium Nernst potential for potassium?

    <p>The potential difference is necessary for resting state function</p> Signup and view all the answers

    What is the significance of living cells always having a membrane potential?

    <p>It maintains a stable environment for cellular processes</p> Signup and view all the answers

    In what way does an unequal distribution of charge aid cellular signaling?

    <p>By facilitating specific ion movements for signaling</p> Signup and view all the answers

    Which equation predicts the membrane potential when it is permeable to more than one substance?

    <p>Goldman Field equation</p> Signup and view all the answers

    In the Goldman Field equation for membrane potential, what does 'V𝑚' represent?

    <p>Membrane potential</p> Signup and view all the answers

    What does the term '𝑝𝐾' represent in the Goldman Field equation?

    <p>Permeability to potassium</p> Signup and view all the answers

    Mary, a patient presenting with numbness in her feet, has a history of which type of diabetes?

    <p>Type 2 diabetes mellitus</p> Signup and view all the answers

    In the context of Mary's condition, what physiological concept relates to the slow progressive numbness in her feet?

    <p>Membrane potential changes</p> Signup and view all the answers

    Which substance's permeability is NOT considered in the Goldman Field equation for membrane potential?

    <p>Sodium (Na+)</p> Signup and view all the answers

    What is the primary role of membrane permeability in determining membrane potential according to the Goldman Field equation?

    <p>Regulating ion flow across the membrane</p> Signup and view all the answers

    What symptoms might be associated with changes in membrane potential due to alterations in ion permeabilities as per the Goldman Field equation?

    <p>Muscle weakness or paralysis</p> Signup and view all the answers

    Which is NOT a factor influencing Mary's slowly progressive numbness according to the text?

    <p>Adequate sleep patterns</p> Signup and view all the answers

    What physiological process serves as a foundation for understanding gradual numbness and coldness in Mary's feet?

    <p>Membrane potential changes</p> Signup and view all the answers

    What is the concentration of Ca+2 in the cytosol of a 'resting' cell?

    <p>0.1 micromolar</p> Signup and view all the answers

    How many Ca+2 ions does each calmodulin bind to before becoming activated?

    <p>Four</p> Signup and view all the answers

    What activates the release of Ca+2 from the endoplasmic reticulum?

    <p>IP3</p> Signup and view all the answers

    What lipid-soluble molecule stays within the cell membrane and diffuses throughout it?

    <p>DAG</p> Signup and view all the answers

    What do both Ca+2 and DAG work together to activate?

    <p>PK C</p> Signup and view all the answers

    Why is there a high concentration gradient for Ca+2 from the ER into the cytosol?

    <p>To allow Ca+2 to enter the cytosol</p> Signup and view all the answers

    What happens when the concentration of Ca+2 increases in the cytosol?

    <p>Calmodulin binds to effectors</p> Signup and view all the answers

    What is the purpose of calmodulin once it is activated?

    <p>To activate PK C</p> Signup and view all the answers

    What is the role of Gi GPCR in cell signaling?

    <p>Downregulates the activity of Gs</p> Signup and view all the answers

    What is the impact of opening a channel that allows sodium to enter the cell on its membrane potential?

    <p>Depolarization</p> Signup and view all the answers

    What is the significance of -90 mV being the Nernst potential for K+?

    <p>It tends to cause most cells to be 'less' activated</p> Signup and view all the answers

    What would happen to the cytosolic calcium concentration if a channel allowing calcium entry was opened?

    <p>Increase</p> Signup and view all the answers

    How does the activity of Na+/K+-ATPase contribute to the cell's membrane potential?

    <p>Creates an inside-negative membrane potential</p> Signup and view all the answers

    Why does sodium want to diffuse into the cell when a channel for sodium opens?

    <p>Due to a low cytosolic concentration of sodium inside the cell</p> Signup and view all the answers

    How does opening a channel for sodium impact the membrane potential?

    <p>Causes depolarization</p> Signup and view all the answers

    What is the purpose of PK C modulating the activity of many other effectors?

    <p>Modulates cellular responses by affecting other effectors</p> Signup and view all the answers

    What is the key function of receptors in the cell membrane as mentioned in the text?

    <p>Transducing extracellular signals into intracellular signals</p> Signup and view all the answers

    In the context of intracellular signaling models, what is the role of the first messenger?

    <p>Binds to and activates cell membrane receptors</p> Signup and view all the answers

    Which event characterizes an active intracellular signaling system according to the model presented in the text?

    <p>Extracellular signal triggers the activation of second messengers</p> Signup and view all the answers

    What is the main function of G-proteins in intracellular signaling as described in the text?

    <p>Amplify the signal by activating effector proteins</p> Signup and view all the answers

    What term best describes the process where cells reduce their response to repeated or continuous stimulation?

    <p>Desensitization</p> Signup and view all the answers

    Which statement accurately represents the role of lipid molecules in intracellular signaling?

    <p>Lipids contribute to signaling by regulating membrane properties and localizing proteins</p> Signup and view all the answers

    What is a key function of second messengers in intracellular signaling pathways?

    <p>Amplify and relay signals from cell surface receptors to effector proteins</p> Signup and view all the answers

    Why are receptors on the cell membrane considered essential components of cellular signaling pathways?

    <p>To transduce extracellular signals into intracellular signals for cellular responses</p> Signup and view all the answers

    What is a key limitation of the model described in the text?

    <p>It oversimplifies the signaling events</p> Signup and view all the answers

    What is the main purpose of the model for categorizing steps in signaling events?

    <p>To offer a quick overview of similarities and differences</p> Signup and view all the answers

    What role does negative feedback play in the model?

    <p>Degradation of 2nd messengers</p> Signup and view all the answers

    What does the G-Protein-Coupled Receptors (GPCR) refer to in the text?

    <p>A type of membrane receptor</p> Signup and view all the answers

    What aspect of the model helps in understanding complex signaling events?

    <p>Categorization of steps</p> Signup and view all the answers

    What is a caveat mentioned regarding the accuracy of the model?

    <p>&quot;It is not perfectly accurate&quot;</p> Signup and view all the answers

    How does the model help in understanding different biological strategies according to the text?

    <p>&quot;By providing quick comparisons&quot;</p> Signup and view all the answers

    What is the main characteristic of receptor tyrosine kinases?

    <p>Intrinsic kinase activity</p> Signup and view all the answers

    How does the binding of a ligand affect receptor tyrosine kinases?

    <p>Dimerizes the receptor</p> Signup and view all the answers

    Which type of molecules can act as ligands for receptor tyrosine kinases?

    <p>Growth factors</p> Signup and view all the answers

    What is the role of phosphorylation in activating receptor tyrosine kinases?

    <p>Activates the receptor's kinase activity</p> Signup and view all the answers

    Which signaling cascade is commonly associated with receptor tyrosine kinases?

    <p>Ras cascade</p> Signup and view all the answers

    What is the role of Ras in the RTK → Ras → MAP K cascade pathway?

    <p>It activates Raf, another small plasma membrane-associated G-protein</p> Signup and view all the answers

    Which molecule is Ras known to directly interact with to initiate its activation in the cell?

    <p>RTK</p> Signup and view all the answers

    What is the key signaling mechanism mentioned in the text that is unique to insulin signaling and involves PI3K?

    <p>Akt system</p> Signup and view all the answers

    Which pathway is most commonly associated with Receptor Tyrosine Kinase (RTK) activation according to the text?

    <p>Ras-Raf-MAP kinase pathway</p> Signup and view all the answers

    What is the mechanism by which Ras inactivates itself within the cell?

    <p>Cleaving GTP into GDP</p> Signup and view all the answers

    What is the final outcome of the RTK → Ras → MAP K cascade pathway?

    <p>Phosphorylation of transcription factors</p> Signup and view all the answers

    Which signaling pathway does Ras primarily contribute to within the cell?

    <p>Ras-Raf-MAP kinase pathway</p> Signup and view all the answers

    What is the main role of PIP3 in the cellular signaling pathway described in the text?

    <p>Bringing PDK1 and Akt together at the membrane</p> Signup and view all the answers

    How is nitric oxide (NO) unique compared to other second messengers mentioned in the text?

    <p>It is rapidly degraded</p> Signup and view all the answers

    What activates PDK1 in the cellular signaling pathway described in the text?

    <p>PIP3</p> Signup and view all the answers

    In the PI3K-Akt signaling pathway, what is the main function of Akt?

    <p>Influencing a range of intracellular targets</p> Signup and view all the answers

    What is the primary source of nitric oxide (NO) production in cells?

    <p>NOs acting on L-arginine</p> Signup and view all the answers

    Which kinase is activated by phosphorylation from PDK1 in the cellular signaling pathway discussed in the text?

    <p>Akt</p> Signup and view all the answers

    What is the major effect of nitric oxide (NO) on smooth muscle?

    <p>Relaxation</p> Signup and view all the answers

    Which enzyme converts PIP2 into IP3 and DAG in the cell membrane?

    <p>PLC</p> Signup and view all the answers

    What brings PDK1 and Akt together at the membrane in the cellular signaling pathway?

    <p>PIP3</p> Signup and view all the answers

    What is a key feature of nitric oxide (NO) that allows it to diffuse across cell membranes quickly?

    <p>Being hydrophobic</p> Signup and view all the answers

    Which model involves pathways related to regulated proteolysis?

    <p>Model 3</p> Signup and view all the answers

    Which model directly involves non-coding RNA affecting transcription?

    <p>Model 5</p> Signup and view all the answers

    Which model includes intracellular receptors like Steroid and Thyroid hormones?

    <p>Model 4</p> Signup and view all the answers

    Which model represents pathways involving activation of transcription factors?

    <p>Model 2</p> Signup and view all the answers

    In the discussed models, which one specifically involves cAMP activating PKA?

    <p>Model 1</p> Signup and view all the answers

    Which model does NOT involve altered protein synthesis?

    <p>Model 3</p> Signup and view all the answers

    Which model is associated with a slower signaling process due to gene transcription?

    <p>Model 5</p> Signup and view all the answers

    Which model involves the AKT pathway activated by PI 3 Kinase?

    <p>Model 1</p> Signup and view all the answers

    How can intracellular signaling cascades affect transcription?

    <p>By affecting transcription factors</p> Signup and view all the answers

    What is the role of co-activators and co-repressors in transcription regulation?

    <p>They bind to transcription factors to influence transcription</p> Signup and view all the answers

    In the context of signaling cascades, which component binds to a transcription factor to modify gene transcription?

    <p>Protein kinase</p> Signup and view all the answers

    What is the effect of an inhibitory enzyme in a signaling cascade model?

    <p>Shuts off the signaling cascade</p> Signup and view all the answers

    Which molecule is responsible for dissociating the catalytic and regulatory subunits of PKA?

    <p>cAMP</p> Signup and view all the answers

    What is the primary function of cAMP in a signaling cascade?

    <p>Activates cAMP-dependent protein kinase</p> Signup and view all the answers

    How does cAMP affect the structure of PKA?

    <p>Causes binding of catalytic and regulatory subunits</p> Signup and view all the answers

    In a signaling cascade, what is the direct consequence of an increase in cytosolic cAMP concentration?

    <p>Activation of cAMP-dependent protein kinase</p> Signup and view all the answers

    How does CaM-Kinase affect gene transcription?

    <p>Activates transcription of genes with a CRE</p> Signup and view all the answers

    What is the function of Protein Kinase C (PKC) when activated?

    <p>Phosphorylates target proteins to activate/inhibit transcription factors</p> Signup and view all the answers

    How is PKC activated?

    <p>By phosphorylating target proteins</p> Signup and view all the answers

    Which protein is activated by receptor tyrosine kinases in the pathway mentioned?

    <p>Ras</p> Signup and view all the answers

    What does Active Ras trigger in the pathway?

    <p>Activation of MAP Kinase (Erk)</p> Signup and view all the answers

    Where can MAP Kinase (Erk) function after being activated?

    <p>Nucleus</p> Signup and view all the answers

    What immediate effect does the activation of MAP Kinase (Erk) have on gene expression?

    <p>Activates transcription factors for immediate early genes</p> Signup and view all the answers

    What is the primary role of PKC in the pathway described?

    <p>Phosphorylate target proteins to regulate gene transcription</p> Signup and view all the answers

    How does cAMP activate PKA in the context of transcription regulation?

    <p>By phosphorylating specific target proteins in the cytoplasm</p> Signup and view all the answers

    What is the role of CREB in transcription regulation?

    <p>Stimulates the transcription of genes with a CRE</p> Signup and view all the answers

    How does CaM Kinase (CaMKinase) affect transcription regulators?

    <p>Phosphorylates transcription regulators to increase or decrease transcription</p> Signup and view all the answers

    What is the function of a co-activator like CREB-binding protein (CBP) in gene transcription?

    <p>Promotes transcription by interacting with activated CREB</p> Signup and view all the answers

    Which enzyme inactivates cAMP to shut off the signal transduction pathway?

    <p>Phosphodiesterase</p> Signup and view all the answers

    How does PKA affect transcription factors as mentioned in the text?

    <p>Enters the nucleus and activates CREB</p> Signup and view all the answers

    What is the function of activated CREB in transcription regulation?

    <p>Promotes gene transcription by phosphorylating target proteins</p> Signup and view all the answers

    Study Notes

    Cell Membrane Components and Functions

    • Phospholipids link to molecules like choline or ethanolamine at their head groups.
    • Fatty acid tails in glycerophospholipids typically have a length of 16-18 carbons.
    • Membrane proteins involved in identifying foreign substances and initiating immune responses are known as receptors or immune receptors.
    • The cytoskeleton maintains cell shape and provides mechanical support through structures like microfilaments and microtubules.
    • Cholesterol is crucial for stabilizing membrane fluidity and integrity.

    Transport Mechanisms and Cell Regulation

    • The cell membrane regulates the passage of molecules through selective permeability.
    • Semi-permeability allows specific substances to pass while blocking others, particularly larger molecules.
    • Aquaporins facilitate the movement of water across the plasma membrane.
    • Na+/K+ ATPase pumps help prevent cell swelling by maintaining ion balance, primarily pumping out sodium and bringing in potassium.
    • Low ATP levels (below 10% of normal) hinder cellular function and energy-dependent processes.

    Signaling and Membrane Receptors

    • Cell membranes rely on receptors for important signaling and metabolic functions.
    • Receptor domains, particularly those extending through the lipid bilayer, are critical for signal transduction.
    • Hydrophobic domains amplify the signal of most cell membrane receptors.
    • Specific cellular signals, such as hormones, determine how cells respond, influenced by receptor configuration and binding.

    Phospholipid Structure and Synthesis

    • Phospholipids consist of a glycerol backbone, two fatty acids, and a phosphate group.
    • Sphingomyelin's backbone is derived from sphingosine instead of glycerol.
    • Typical phosphoglycerides include phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine.
    • Phospholipid synthesis starts with the attachment of fatty acids to the glycerol backbone, primarily occurring in the endoplasmic reticulum (ER).

    Cholesterol Synthesis and Regulation

    • Cholesterol synthesis primarily occurs in the liver and other cells, with HMG-CoA reductase as the key regulatory enzyme.
    • Insulin stimulates, while glucagon inhibits HMG-CoA reductase activity, regulating cholesterol levels.
    • Cholesterol has a structure featuring four fused rings and plays roles in membrane fluidity and stability.
    • High intracellular cholesterol levels inhibit further synthesis by promoting HMG-CoA reductase phosphorylation.

    Fluid Dynamics and Transport

    • The flow of a substance from one point to another is driven by energy gradients.
    • Poiseuille's law describes the flow rate of liquids or gases through tubes, influenced by parameters like pressure difference and tube diameter.
    • Every system has resistance to flow, impacting the movement of substances, which is defined by Fick's law and Ohm's law in physiological contexts.
    • The Nernst equation is used to calculate the electrochemical gradient across membranes, indicating the equilibrium potential for a given ion.

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    Physiology Concepts Lectures 1-4

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