Effects Of Insulin And Glucagon! Biochemistry Trivia Quiz

The labeled subunit A is involved in binding the receptor to the insulin molecule.

The correct answer is Pancreatic Beta cell. These cells are responsible for releasing insulin in the pancreas. Insulin plays a crucial role in regulating blood sugar levels by allowing cells to take in glucose from the bloodstream. When blood sugar levels are high, beta cells release insulin to lower them. Dysfunction or destruction of these cells can lead to insulin deficiency and the development of diabetes.

Receptor tyrosine kinase is a type of enzyme that plays a crucial role in cell signaling. It is responsible for phosphorylating other proteins, such as insulin receptor substrates (IRS). This phosphorylation process is important for the activation of downstream signaling pathways, ultimately leading to various cellular responses. Therefore, the statement that receptor tyrosine kinase phosphorylates other proteins, including IRS, is true.

Glucagon is a hormone that is secreted by the alpha cells of the Islets of Langerhans into the blood vessels. It is not secreted by acinar cells into the pancreatic duct, beta cells of the Islets of Langerhans into the pancreatic duct, or Islets of Langerhans cells into blood vessels.

Correct Answer: C. Stimulation of Fatty acid and TAG synthesis occurs in the liver and adipose tissue. A. occurs in all three tissues (liver, adipose, muscle). B. occurs in Adipose tissue only. D. occurs in all three tissues.

Insulin binding to the insulin receptor activates tyrosine kinase activity in the intracellular domain of the beta subunit. This means that when insulin binds to the receptor, it triggers a signaling cascade that leads to the activation of tyrosine kinase enzymes. These enzymes play a crucial role in various cellular processes, including glucose uptake and metabolism. Therefore, the statement is true.

The liver is considered the nutrient distribution center because it plays a crucial role in processing and distributing nutrients throughout the body. It receives nutrients from the intestines and processes them into forms that can be used by the body's cells. The liver also stores and releases glucose as needed, regulates cholesterol levels, and produces bile to aid in digestion. Additionally, it detoxifies harmful substances and metabolizes drugs, making it an essential organ for overall health and well-being.

Insulin secretion is stimulated by high levels of glucose and amino acids in the blood, as well as the presence of glucokinase in beta cells. However, scarcity of food does not stimulate insulin secretion. When food is scarce, the body conserves energy by reducing insulin secretion, as insulin promotes the storage of nutrients and energy. Therefore, scarcity of food is not a stimulator of insulin secretion.

Adipose tissue primarily functions to store excess fatty acids that are derived from circulating TAGs and chylomicrons. These fatty acids are stored in the form of TAGs within adipocytes. This storage of fatty acids helps to maintain energy balance in the body and provides a readily available source of fuel when needed.

Pancreatic Alpha cells release glucagon. Glucagon is a hormone that helps to regulate blood sugar levels. When blood sugar levels are low, the alpha cells in the pancreas release glucagon, which signals the liver to convert stored glycogen into glucose and release it into the bloodstream. This helps to increase blood sugar levels.

Insulin is a hormone that is released by the pancreas in response to high levels of glucose in the blood. It helps regulate blood sugar levels by promoting the uptake and utilization of glucose by cells. In the liver, insulin has two major effects during the feed cycle. Firstly, it promotes glucose consumption through glycolysis, which is the breakdown of glucose to produce energy. It also stimulates glycogen synthesis, which is the storage of glucose in the form of glycogen. Secondly, insulin stimulates the synthesis of fatty acids and triglycerides (TAG) in the liver. This is important for storing excess glucose as fat for later use. Therefore, the correct answer is glucose consumption (glycolysis and glycogen synthesis), fatty acid and TAG synthesis.

Hypoglycemia is identified by a blood glucose level that is below 55 mg/dl. This indicates that the individual has low blood sugar levels, which can lead to symptoms such as dizziness, confusion, and weakness. Monitoring blood glucose levels is important in identifying and managing hypoglycemia.

The absorptive state occurs 2-4 hours after a meal. During this state, the body is actively absorbing and utilizing the nutrients from the recently consumed meal. This is when the blood glucose levels are elevated, and insulin is released to facilitate the uptake of glucose by cells for energy production or storage. The absorbed nutrients are used to replenish energy stores, build new tissues, and support various metabolic processes. After this period, the body enters the post-absorptive state, where it starts using stored energy reserves to meet its energy needs.

The islets of Langerhans are specialized regions within the pancreas that are responsible for producing and releasing hormones such as insulin and glucagon. These hormones play a crucial role in regulating blood sugar levels. The pancreas is composed of various types of cells, and the islets of Langerhans make up only a small percentage, approximately 1-2%, of the total pancreatic cells. Therefore, the statement that the islets of Langerhans only make up about 1-2% of the total pancreas cells is true.

Glucose is the correct answer because it is the primary source of energy for the brain. The blood-brain barrier is a protective barrier that prevents most substances from entering the brain, but glucose is an exception. The brain relies on a constant supply of glucose to function properly, and it can transport glucose across the blood-brain barrier using specialized transporters. Other fuels such as amino acids, TAGs, and fatty acids cannot easily cross the blood-brain barrier and therefore cannot be used as direct sources of energy for the brain.

Glucagon is actually secreted out of the islet of Langerhans cells directly into blood vessels, just like insulin. Therefore, the statement is incorrect and the correct answer is False.

In the pancreatic beta-cell, preproinsulin undergoes processing to form proinsulin, which is then further processed to form insulin. This processed insulin is then secreted from the pancreatic beta-cell.

The liver is responsible for maintaining homeostasis in the body by regulating nutrient availability to the peripheral tissues. It stores excess nutrients such as glucose and releases them when needed, thus buffering large variations in nutrient availability. Additionally, the liver metabolizes and detoxifies various substances, further contributing to its role in regulating nutrient levels in the body.

Adipose tissue is the correct answer because it is the primary site of energy storage in the body. It is made up of fat cells, which store excess energy in the form of triglycerides. When the body needs energy, these triglycerides are broken down and released into the bloodstream to be used as fuel. Adipose tissue also serves as insulation and protection for organs. The liver, brain, and muscle do not primarily function as energy storage depots.

Insulin stimulates tyrosine kinase, an enzyme that plays a crucial role in insulin signaling pathways. When insulin binds to its receptor on the cell surface, it activates the receptor's tyrosine kinase activity. This leads to the phosphorylation of tyrosine residues on intracellular proteins, initiating a cascade of signaling events that ultimately result in the uptake of glucose into cells and the regulation of various metabolic processes. Therefore, option C is the correct answer as it accurately describes the effect of insulin on tyrosine kinase.

The correct answer is that the endocrine pancreas consists of groups of cells known as islets of Langehans which are embedded in the exocrine portion of the gland. This means that the cells responsible for secreting insulin and glucagon are located within the exocrine portion of the pancreas, rather than in a separate part of the gland.

Insulin signaling plays a crucial role in regulating glucose and nutrient metabolism in the body. It promotes glucose uptake by muscles and adipose tissue, but inhibits glucose production in the liver. Insulin also stimulates protein synthesis and inhibits protein breakdown in skeletal muscles. Therefore, the correct answer is C, as an increase in amino acid uptake by the skeletal muscles is a result of insulin signaling.

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Insulin receptor can be controlled by insulin binding and subsequent dissociation. When insulin binds to the receptor, it triggers a cascade of signaling events that regulate various cellular processes, including glucose uptake and metabolism. Once the desired effects are achieved, insulin dissociates from the receptor, allowing the receptor to become available for further signaling events. Therefore, the statement is true.

The correct answer is Letter C shows a giant lipid droplet flattens the nucleus and cytoplasm at one end of the cell. This is because the image clearly depicts a large lipid droplet that is pushing against the nucleus and cytoplasm, causing them to flatten. This can be observed by the displacement and distortion of the cellular components in the image.

Active Glucokinase inside the Beta cells activates the secretion of Insulin from the Pancreas. Glucokinase is an enzyme that helps in the metabolism of glucose. When glucose is metabolized by Glucokinase inside the Beta cells of the Pancreas, it leads to the production of ATP. This increase in ATP levels triggers the release of Insulin from the Pancreas. Therefore, the presence of active Glucokinase inside the Beta cells is necessary for the secretion of Insulin.

The statement is false because after the autophosphorylation of tyrosine and the phosphorylation of intracellular proteins, multiple signaling pathways can be activated by glucose. Glucose can activate various pathways such as the insulin signaling pathway, the AMP-activated protein kinase (AMPK) pathway, and the mammalian target of rapamycin (mTOR) pathway, among others. Therefore, it is not accurate to say that only one signaling pathway is activated by glucose.

Insulin inhibits lipolysis, which is the breakdown of fats into fatty acids. It also inhibits glycogenolysis, which is the breakdown of glycogen into glucose. Additionally, insulin inhibits protein degradation, which is the breakdown of proteins into amino acids. These inhibitory effects of insulin help to promote energy storage and anabolic processes in the body.

Insulin causes the stimulation of glycogenesis (the formation of glycogen) and the inhibition of glycogenolysis (the breakdown of glycogen) in the liver, adipose tissue, and muscle. This means that insulin promotes the storage of glucose as glycogen in these tissues and prevents the breakdown of glycogen back into glucose. The pancreas is not affected by insulin in terms of glycogenesis and glycogenolysis. Therefore, the correct answer is I, III & IV only.

Insulin binding does not lead to the dephosphorylation of tyrosine residues of the beta subunit. In fact, insulin binding activates the insulin receptor, leading to the phosphorylation of tyrosine residues on the beta subunit. This phosphorylation is an important step in the signaling cascade triggered by insulin binding, which ultimately leads to various cellular responses such as glucose uptake and metabolism. Therefore, the correct answer is false.

After the consumption of a large bowl of ice cream, one would expect to observe an increase in liver fructose 2,6-bisphosphate levels. This is because ice cream contains a high amount of sugar, which is broken down into fructose in the body. Fructose is then converted into fructose 1-phosphate, which is further converted into fructose 1,6-bisphosphate. Fructose 1,6-bisphosphate is then converted into fructose 2,6-bisphosphate, which is an allosteric activator of the enzyme phosphofructokinase-1 (PFK-1). PFK-1 is a key enzyme in glycolysis, and its activation by fructose 2,6-bisphosphate leads to an increase in glycolysis and the production of ATP. Therefore, after consuming a large amount of fructose from ice cream, the liver would increase its production of fructose 2,6-bisphosphate to enhance glycolysis and ATP production.

Insulin stimulates amino acid uptake in muscle tissues. This is because insulin promotes the transport of glucose and amino acids into muscle cells, where they can be used for energy and protein synthesis. In contrast, insulin does not have a significant effect on amino acid uptake in the liver, adipose tissue, pancreas, or brain.

During sudden flight or fight situations, the body requires a rapid source of energy to fuel the muscles. Glycogenolysis is the process by which glycogen stored in the muscles is broken down into glucose, which can then be used as a fuel source. This process is activated in the muscles to provide the necessary energy for physical activity during these situations. Therefore, option F is the correct answer.

Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. It has several effects on the body, including increasing glucose uptake by cells, increasing glycogen synthesis (the storage form of glucose), decreasing glycogenolysis (the breakdown of glycogen), and decreasing gluconeogenesis (the production of glucose from non-carbohydrate sources). However, insulin does not decrease glycogenesis, which is the process of converting glucose into glycogen. Instead, insulin promotes glycogenesis. Therefore, the correct answer is "Decreased glycogenesis."

The normal AST/ALT ratio is approximately 1.3. This means that the levels of aspartate aminotransferase (AST) are slightly higher than the levels of alanine aminotransferase (ALT) in the blood. This ratio is used as a marker for liver health, as an increased ratio may indicate liver damage or disease.

In alcoholic hepatitis, AST (aspartate aminotransferase) levels are typically higher than ALT (alanine aminotransferase) levels. This is because AST is found in both the liver and other organs such as the heart and muscles, while ALT is primarily found in the liver. Therefore, when there is liver damage due to alcohol consumption, AST levels tend to rise more significantly than ALT levels.

In viral hepatitis, the levels of alanine aminotransferase (ALT) are typically higher than the levels of aspartate aminotransferase (AST). This is because ALT is predominantly found in the liver, while AST is present in multiple tissues including the liver, heart, and muscles. Therefore, when the liver is damaged, such as in viral hepatitis, the ALT levels increase more significantly than AST levels.

Insulin is primarily secreted in response to elevated blood glucose levels. When food is consumed, the intestine secretes certain hormones, such as incretins, which stimulate insulin secretion. Amino acids, especially arginine, also stimulate insulin secretion. Additionally, glucose itself is a potent stimulator of insulin secretion. Therefore, secretion from the intestine following food intake, amino acids in the blood (esp. arginine), and glucose in the blood are all stimulators of insulin secretion.

The alpha subunit is not an intracellular effector involved in insulin function. Insulin signaling involves the activation of insulin receptor substrate (IRS), which acts as a docking protein for downstream signaling molecules. Adaptors are also involved in insulin signaling by facilitating the interaction between different signaling molecules. Enzyme effectors, such as phosphatidylinositol 3-kinase (PI3K), play a crucial role in mediating the metabolic effects of insulin. However, the alpha subunit is not directly involved in insulin signaling and is not considered an intracellular effector in this context.

Fructose 2, 6 bisphosphate is known to be a potent activator of phosphofructokinase 1 (PFK-1), an enzyme involved in glycolysis. By stimulating PFK-1, fructose 2, 6 bisphosphate increases the rate of glycolysis, leading to the production of ATP and other metabolic intermediates. This is consistent with option A, which states that fructose 2, 6 bisphosphate stimulates PFK-1 and increases glycolysis.

During the post absorptive period, the body is in a fasting state and is not actively digesting and absorbing nutrients from the gastrointestinal tract. Glucagon, a hormone released by the pancreas, increases during this period to stimulate the breakdown of glycogen in the liver and release glucose into the bloodstream. This helps to maintain blood sugar levels during fasting. Therefore, the statement "C. Glucagon secretion increases" accurately describes what happens during the post absorptive period as compared to the postprandial period.

The liver responds to high blood glucose levels by increasing the phosphorylation of glucose using glucokinase. Glucokinase has a high Km for glucose, meaning it has a low affinity for glucose. This allows the liver to efficiently phosphorylate glucose even at high concentrations, helping to regulate blood glucose levels. By increasing the phosphorylation of glucose, the liver promotes its storage as glycogen or conversion into fatty acids for storage.

Glycogen phosphorylase kinase is inactive in its dephosphorylated state. This enzyme is responsible for phosphorylating and activating glycogen phosphorylase, which in turn breaks down glycogen into glucose. When glycogen phosphorylase kinase is dephosphorylated, it cannot phosphorylate glycogen phosphorylase, resulting in the inhibition of glycogen breakdown. Therefore, the correct answer is glycogen phosphorylase kinase.

Glycogen phosphorylase kinase is inactive in its dephosphorylated state. This enzyme plays a crucial role in the regulation of glycogenolysis, the breakdown of glycogen into glucose. When the enzyme is phosphorylated, it becomes activated and can catalyze the phosphorylation of glycogen phosphorylase, which in turn activates glycogenolysis. However, in its dephosphorylated state, glycogen phosphorylase kinase is unable to phosphorylate glycogen phosphorylase, rendering it inactive and preventing the breakdown of glycogen.

The answer is C. The major regulated step of glycolysis is the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, catalyzed by the enzyme PFK-1. PFK1 is activated by both F- 2,6-BP and AMP and inhibited by ATP and citrate. The modulation of F-2,6-BP levels in the liver is controlled by the insulin-to-glucagon ratio in the blood, which is tied to the regulation of PFK- 2, the enzyme that both produces and degrades F-2,6-BP. Glucose 6-phosphate acts by negative
feedback inhibition on hexokinase (an enzyme not present in liver), whereas acetyl CoA is an inhibitor of the pyruvate dehydrogenase reaction.

During the early stages of fasting, the body needs a constant source of energy to function properly. Since glucose is the primary source of energy for the body, the liver releases stored glucose into the bloodstream to ensure a steady supply. This process is known as glycogenolysis, where glycogen (stored glucose) is broken down into glucose molecules. By releasing glucose from the liver, the body can maintain normal blood sugar levels and provide energy to various organs and tissues.

High ADP inside the β cell of the pancreas inhibits insulin secretion. When blood glucose levels are high, glucose is taken up by the β cells of the pancreas and undergoes glycolysis, producing ATP. The ATP is then converted to ADP by the enzyme ATPase. The high levels of ADP inhibit ATP-sensitive potassium channels, which leads to depolarization of the β cell membrane and the subsequent release of insulin. Therefore, high levels of ADP inside the β cell inhibit insulin secretion.

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