General Knowledge Quiz
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Questions and Answers

What characterizes a senescent cell?

  • Cells that can divide temporarily
  • Cells that only divide in response to signals
  • Cells that can no longer divide permanently (correct)
  • Cells that divide actively
  • Which phase of the cell cycle involves DNA synthesis?

  • G1 phase
  • S phase (correct)
  • M phase
  • G2 phase
  • What role do cyclins play in the cell cycle?

  • They are responsible for cell apoptosis
  • They enhance the rate of DNA replication
  • They inhibit the cell cycle progression
  • They activate checkpoints (correct)
  • In which phase do cells prepare for division?

    <p>G2 phase (B)</p> Signup and view all the answers

    What is the primary function of checkpoints in the cell cycle?

    <p>To ensure accurate DNA duplication (B)</p> Signup and view all the answers

    What can lead to cancer formation regarding regulatory signals?

    <p>Both stimulators and inhibitors can contribute (B)</p> Signup and view all the answers

    During which checkpoint is the cell often most disrupted in cancer?

    <p>G1/S checkpoint (B)</p> Signup and view all the answers

    What happens at the restriction point in the cell cycle?

    <p>Cells commit to the cell cycle and division (A)</p> Signup and view all the answers

    Which type of UV rays is primarily responsible for inducing cutaneous cancers?

    <p>UV-B (280-320 nm) (D)</p> Signup and view all the answers

    What type of radiation includes alpha, beta, protons, and neutrons?

    <p>Ionizing radiation (B)</p> Signup and view all the answers

    What is the primary mutagenic effect of UV-C radiation?

    <p>Formation of pyrimidine dimers in DNA (A)</p> Signup and view all the answers

    What kind of damage can occur with extensive exposure to UV radiation?

    <p>Overwhelmed DNA repair systems (C)</p> Signup and view all the answers

    Which population is especially susceptible to radiation-induced neoplasia?

    <p>Individuals with defects in DNA excision repair enzymes (B)</p> Signup and view all the answers

    What is a common effect of lun exposure to UV rays?

    <p>Killing of cells (D)</p> Signup and view all the answers

    In what organ is acute leukemia most commonly observed following radiation exposure?

    <p>Bone marrow (C)</p> Signup and view all the answers

    What is the latency period for radiation-induced neoplasia in atomic bomb survivors?

    <p>7 years (B)</p> Signup and view all the answers

    What primary role does glucagon play in the body?

    <p>Raises blood glucose levels (D)</p> Signup and view all the answers

    Which process is NOT promoted by insulin?

    <p>Glycogenolysis (C)</p> Signup and view all the answers

    How does glucagon affect the liver during fasting?

    <p>Stimulates gluconeogenesis (B)</p> Signup and view all the answers

    What triggers the release of insulin after a meal?

    <p>Absorption of carbohydrates from the digestive tract (C)</p> Signup and view all the answers

    Which of the following processes does insulin NOT facilitate?

    <p>Release of free fatty acids (D)</p> Signup and view all the answers

    What physiological state occurs immediately after consuming a meal?

    <p>Postprandial state (D)</p> Signup and view all the answers

    Which mechanism describes glucagon's action on glycogen?

    <p>Promotes glycogen breakdown (D)</p> Signup and view all the answers

    What is the correct incubation temperature for the glucose test that can be used for 10 minutes?

    <p>15-25°C (D)</p> Signup and view all the answers

    During fasting, blood glucose levels gradually decrease due to:

    <p>Utilization of available glucose (C)</p> Signup and view all the answers

    Which of the following substances may interfere with the glucose test?

    <p>Urea (D)</p> Signup and view all the answers

    What is used to set the spectrophotometer to 'zero' before measuring absorbance?

    <p>Blank test tube (D)</p> Signup and view all the answers

    Which measuring device is used to determine the absorbance at 505 nm?

    <p>Spectrophotometer (C)</p> Signup and view all the answers

    What formula is used to calculate glucose concentration in the sample?

    <p>Glucose (mg/dL) = (A) Sample / (A) Standard × Standard Concentration (B)</p> Signup and view all the answers

    What is the appropriate control sample for this glucose testing method?

    <p>Glucose standard solution (A)</p> Signup and view all the answers

    What is the primary purpose of stabilizers and activators in the glucose test?

    <p>To maintain the pH of the reaction (B)</p> Signup and view all the answers

    What is the result of elevated blood glucose levels in the body?

    <p>Potential development of diabetes (A)</p> Signup and view all the answers

    What is the effect of phosphorylation on the RB1 protein during the cell cycle?

    <p>It releases inhibition of E2F transcription factors. (B)</p> Signup and view all the answers

    Which of the following statements is true regarding mutations in the RB1 gene?

    <p>They result in the formation of defective pRB. (D)</p> Signup and view all the answers

    How do viral oncoproteins such as HPV E7 affect RB1 function?

    <p>They bind, sequester, and degrade pRB. (B)</p> Signup and view all the answers

    What is the main function of the RB1 gene product, pRB, in normal cell proliferation?

    <p>To bind and inactivate E2F transcription factors. (C)</p> Signup and view all the answers

    In cancer, how is RB1 generally inactivated?

    <p>Through mutations or hyperphosphorylation. (B)</p> Signup and view all the answers

    What role does p53 play in relation to RB1 loss in tumorigenesis?

    <p>It protects against RB1-loss induced apoptosis. (C)</p> Signup and view all the answers

    What effect does hyperphosphorylation of RB1 have on gene expression?

    <p>It primarily de-represses only cell cycle genes. (A)</p> Signup and view all the answers

    Which tissues express the RB1 gene product, pRB?

    <p>In various tissues including osteoblast, fibroblast, and skin. (A)</p> Signup and view all the answers

    What is the primary reason for insulin deficiency in individuals with type 1 diabetes?

    <p>Destruction of insulin-producing beta cells (B)</p> Signup and view all the answers

    Which of the following describes the blood glucose level management for individuals with type 2 diabetes?

    <p>Often managed with lifestyle changes and oral medications (D)</p> Signup and view all the answers

    What are the target postprandial blood glucose levels for both type 1 and type 2 diabetes?

    <p>Less than 180 mg/dL (10.0 mmol/L) (B)</p> Signup and view all the answers

    Which complication is most directly associated with poorly controlled blood glucose levels in diabetes?

    <p>Stroke (C)</p> Signup and view all the answers

    What is a significant consequence of elevated blood glucose levels over time?

    <p>Potential damage to blood vessels and nerves (C)</p> Signup and view all the answers

    What is the general approach to managing blood glucose levels in type 1 diabetes?

    <p>Regular monitoring and insulin administration (C)</p> Signup and view all the answers

    What factor distinguishes type 2 diabetes from type 1 diabetes regarding insulin production?

    <p>Type 2 diabetes involves insulin resistance rather than complete deficiency (A)</p> Signup and view all the answers

    Which of the following statements about fasting blood glucose levels is accurate for both types of diabetes?

    <p>Normal fasting levels are between 80-130 mg/dL (C)</p> Signup and view all the answers

    Flashcards

    Blood Glucose

    The concentration of glucose in the blood, a crucial energy source for cells.

    Insulin

    A hormone that regulates blood glucose levels by promoting glucose uptake and storage.

    Hyperglycemia

    High blood glucose levels (above 180 mg/dL after meals or 125 mg/dL fasting).

    Hypoglycemia

    Low blood glucose levels (below 70 mg/dL).

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    Diabetes Mellitus

    Chronic condition with high blood glucose levels due to insufficient insulin or impaired insulin function.

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    Fasting Blood Glucose

    Blood glucose level measured after an overnight fast (no food).

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    Oral Glucose Tolerance Test (OGTT)

    Test to assess how the body handles glucose after a glucose load.

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    Glycated Hemoglobin (HbA1c)

    Blood test measuring average blood glucose levels over several months.

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    G0 phase

    Resting phase of the cell cycle where cells are not actively dividing.

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    Senescent Cell

    A cell that can no longer divide (permanently in G0).

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    Quiescent Cell

    A cell that doesn't divide when it reaches maturity or terminal differentiation.

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    Cell Cycle

    Series of events that cells go through as they grow and divide.

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    G1 Phase

    Cell prepares for DNA duplication; long gap (6-12 hours).

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    S Phase

    DNA synthesis and duplication phase.

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    G2 Phase

    Cell prepares for cell division.

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    M Phase

    Cell division and formation of two daughter cells.

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    Cyclin-CDK

    Protein kinases that regulate cell cycle progression at checkpoints.

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    Checkpoints

    Control points in the cell cycle that determine if a cell proceeds to the next stage.

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    Protooncogenes

    Normal genes that regulate cell cycle progression.

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    Oncogenes

    Mutated protooncogenes that promote uncontrolled cell division.

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    Tumor Suppressor Genes

    Genes that inhibit cell growth and division.

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    Point Mutation

    Single change in a DNA sequence.

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    Gene Amplification

    Increased number of copies of a specific gene.

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    Gene translocation

    Movement of a gene segment to a different chromosome location.

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    Cell Cycle Checkpoints

    Control points in the cell cycle that ensure proper division. They check for errors and ensure the cell is ready for the next stage.

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    G1/S Checkpoint

    This checkpoint in late G1 makes sure the cell is ready to commit to replicating its DNA. It's often disrupted in cancer.

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    What are physical carcinogens?

    Physical agents like UV rays and ionizing radiation that can cause cancer by damaging DNA and altering cell growth.

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    How do UV rays cause cancer?

    UV rays, especially UV-B, can damage DNA by forming pyrimidine dimers, leading to mutations that may overwhelm repair systems and result in skin cancer.

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    What are the effects of ionizing radiation?

    Ionizing radiation includes various forms like X-rays and alpha particles, all of which have the potential to cause cancer by damaging DNA.

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    What are the specific targets of ionizing radiation?

    Ionizing radiation is particularly harmful to bone marrow and the thyroid gland, leading to leukemia and thyroid cancer respectively.

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    What is the relationship between UV rays, melanin, and skin cancer?

    The amount of melanin in the skin acts as a protective barrier against UV rays, but excessive exposure can still overwhelm the protection and cause skin cancer.

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    Why are individuals with DNA repair deficiencies more susceptible to cancer?

    Defective enzymes involved in DNA repair processes leave cells vulnerable to accumulating mutations, leading to higher chances of developing cancer.

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    What are the key effects of UV rays on cells?

    UV rays can damage DNA, inhibit cell division, inactivate enzymes, and even kill cells, leading to various skin problems.

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    What is the role of the nucleoside excision repair pathway?

    This pathway repairs DNA damage, specifically pyrimidine dimers, induced by UV rays. It acts as a defense mechanism against potential cancer development.

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    RB1 gene function

    The RB1 gene produces a protein called pRB that acts as a tumor suppressor. pRB regulates the transition from G1 to S phase by binding to and inactivating E2F transcription factors, preventing the expression of cell cycle genes.

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    RB1 mutations

    Mutations in the RB1 gene disrupt the normal function of pRB, leading to uncontrolled cell division. These mutations can be either 'loss of function,' where pRB is defective and cannot inactivate E2F, or 'gain of function', where pRB is hyperphosphorylated and disengaged from E2F prematurely.

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    E2F transcription factors

    E2F transcription factors are a group of proteins that control the expression of genes involved in cell cycle progression. When pRB is active, it binds to and inactivates E2F, preventing the expression of those genes and halting the cell cycle.

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    How RB1 inactivation leads to cancer

    Inactivation of RB1, whether through mutations or hyperphosphorylation, leads to uncontrolled cell division and the potential for cancer development. This is because the cell cycle is deregulated, and E2F is free to activate cell cycle genes, promoting continuous proliferation.

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    MDM2 and RB1

    The MDM2 protein, a product of the MDM2 oncogene, can bind to and inhibit pRB, essentially removing the brake on cell cycle progression and promoting unchecked cell division.

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    Viral oncoproteins and RB1

    Certain viral oncoproteins, like those produced by adenovirus, SV40, and HPV, can bind to and degrade pRB. This effectively removes the pRB brake, leading to uncontrolled cell division and tumor growth.

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    RB1 and apoptosis

    RB1 can also regulate apoptosis, a programmed cell death process that eliminates damaged or unwanted cells. Loss of RB1 function can lead to increased apoptosis because the cell is unable to appropriately regulate the expression genes that determine cell fate.

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    RB1 and tumor suppression

    RB1 is a critical tumor suppressor gene. By preventing uncontrolled cell division and regulating apoptosis, RB1 contributes to the overall regulation of cell growth and development, suppressing the formation of tumors.

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    Glucose Test Principle

    The test utilizes a colorimetric reaction where glucose in the sample reacts with a reagent, causing a change in color that is measured by a spectrophotometer. The amount of color change is proportional to the glucose concentration.

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    Interfering Substances

    Various substances may interfere with the test, leading to inaccurate results. These include bilirubin, hemoglobin, and some medications. They can react with the reagent, causing false positive results.

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    Reference Values

    Normal blood glucose levels vary slightly but typically range between 70-100 mg/dL when fasting and <140 mg/dL after a meal.

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    Elevated Blood Glucose

    Elevated blood glucose levels can indicate various conditions like diabetes mellitus, hyperglycemia, or hormonal imbalances. In these cases, the body either doesn't produce enough insulin or can't use it effectively, leading to high blood sugar.

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    Role of Insulin

    Insulin is a hormone that regulates blood glucose levels by promoting glucose uptake and storage in cells. It acts like a gatekeeper, allowing sugar to enter cells for energy or storage.

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    Hyperglycemia vs. Hypoglycemia

    Hyperglycemia is high blood glucose levels, often seen in diabetes. Hypoglycemia is low blood glucose levels, which can occur due to excessive insulin, lack of food, or certain medical conditions.

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    Glucose Synthesis

    The body synthesizes glucose through a process called gluconeogenesis, primarily in the liver. This process converts non-carbohydrate sources like amino acids and glycerol into glucose.

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    Primary Sources of Glucose

    The primary sources of glucose in the diet are carbohydrates, such as starches, sugars, and fibers. These carbohydrates are broken down into glucose during digestion.

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    Glucagon

    A hormone released by the pancreas that raises blood glucose levels by stimulating glycogen breakdown and glucose production.

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    Glycogenolysis

    The breakdown of glycogen (stored glucose) into glucose, releasing it into the bloodstream.

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    Gluconeogenesis

    The production of glucose from non-carbohydrate sources, such as amino acids and glycerol, in the liver.

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    Lipolysis

    The breakdown of stored fat (triglycerides) into free fatty acids and glycerol, releasing them into the bloodstream for energy.

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    Postprandial State

    The state after a meal, when blood glucose levels are elevated due to the absorption of glucose.

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    Postabsorptive State

    The state after absorption of nutrients from a meal, when blood glucose levels are gradually decreasing.

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    How do insulin and glucagon work together?

    Insulin and glucagon work in tandem to maintain stable blood glucose levels. Insulin lowers blood glucose, while glucagon raises it, like a seesaw.

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    Type 1 Diabetes

    An autoimmune disease where the immune system attacks insulin-producing cells in the pancreas, leading to little or no insulin production.

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    Type 2 Diabetes

    A condition where the body either doesn't produce enough insulin or can't use it properly, causing high blood glucose levels.

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    Blood Glucose Fluctuations

    Variations in blood glucose levels occur due to insulin deficiency or resistance in both type 1 and 2 diabetes.

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    Insulin Therapy

    The use of insulin injections or an insulin pump to manage blood glucose levels, essential for type 1 diabetes.

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    Lifestyle Changes

    Changes in diet and exercise can significantly impact blood glucose management in type 2 diabetes.

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    Cardiovascular Complications

    Diabetes can damage blood vessels, increasing the risk of heart disease, heart attacks, and stroke.

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    Monitoring Blood Glucose

    Regularly checking blood glucose levels is crucial for both type 1 and 2 diabetes, ensuring optimal management.

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    Complications of Diabetes

    Long-term poorly controlled blood sugar can damage organs and systems like the heart, kidneys, eyes, and nerves.

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