9/28/2012 TEST RAD BIO CH

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9/28/2012 TEST RAD BIO CH
2012-09-27 18:07:14

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  1. Tumors are the result of...
    Abnormal cell proliferation
  2. What occurs when a stem cell undergoes mitosis and divides into daughter cells?
    Cell differentiation
  3. During _________ __________ cells continue to divide and differentiate until a mature cell with a specific function results.
    • Cellular differentiation
    • Which breaks down to, when the cell is maturing into its own cell and becoming less specialized into a more specialized. cell
  4. What is a disease of the genes?
  5. Normal_______ _____ contain genes that promote growth and genes that suppress growth, both of which are important to control the growth of the cell.
    somatic cells
  6. what 2 things are important to the growth of a cell?
    the ability to promote and suppress growth.
  7. When cellular differentiation is disrupted, the daughter cells may continue to divide with no resulting mature cell, thus causing....
    abnormal cellular proliferation AKA Tumor
  8. Note:
    In a tumor cell, the counter balance between promoting growth and suppressing growth is missing.
  9. normal genes that play a part in controlling normal growth and differentiation
    proto oncogenes
  10. What are the pre cursors for the oncogenes?
    Proto oncogenes
  11. These are implicated in the abnormal proliferation of cells. These are the genes that regulate the development and growth of cancerous tissue.
  12. What transforms a proto oncogene into oncogene and results in unrestricted cellular growth?
    mutations, translocations, and gene amplication of which all are DNA mutations
  13. These are tumor suppressing genes
  14. Inactivation of this gene allows the malignant process to flourish
  15. For normal somatic cells, exposure to what can cause DNA mutations?
    sunlight, cigarette smoke, and radiation
  16. What is the 1st and 2nd growth phase?
    G1 and G2
  17. What is the phase where living cells are fully functional but not programmed for mitosis and are basically in the resting phase?
  18. Which phase is the most rapid?
  19. How long is the length of time spent in G1 phase?
    hours to years depending on if the cell is a slow growing cell or not.
  20. When are cells the most sensitive to radiation?
    During G2 and M phase
  21. dead tissue
  22. Tumor growth is a result of an imbalance between _____ and ______
    replication and cell death
  23. As the tumor grows larger, the blood and nutrient supply are inadequate creating areas of
  24. Cancer cells do not _____after a programmed # of cell divisions as do normal cells. They have the ability to ______ indefinitely.
    • die
    • proliferate
  25. Which organelle is responsible for protein synthesis?
  26. What houses the genetic material of a cell that directs cellular metabolism?
  27. which organelle is responsible for storage and manages intracellular chemical substances?
    Golgi Apparatus
  28. How long does mitosis generally take?
    2 hours
  29. Note:
    Radiation is most effective on cells that are actively dividing.
  30. What are the building blocks of life?
  31. In a process called_____________, enzymes in the cells nucleus facilitate the transfer of information from a strand of DNA to RNA.
  32. Ribosomes are the site of ____________ at which the message borne by the mRNA is apprehended by another type of RNA termed transfer RNA and is restated in the language of peptides.
  33. How much of the cell contains water and because of this the probabilityof damage by indirect effects is much greater than for direct effects.
  34. It is usual to classify ionizing radiation as
    electomagnetic or particulate
  35. Indirect effects predominate with sparsely ionizing radiation or_____________ radiations can be modified by physical, chemical, or biological factors.
    low linear energy transfer LET
  36. Because of the cell mostly consisting of water, the probability of damage occurring through________ action is greater than the probability of damage through_____ action.
    • indirect
    • direct
  37. Radiations can be catergorized by the rate at which energy is deposited by charged particles (incident or secondary) as they travel through matter. This is called the ____ of the radiation
  38. How are sparsely ionized radiations such as xrays and gamma rays classified?
    Low LET because the secondary electrons produced are small particles that deposit their energy over great distances.
  39. Densely ionizing radiations, which include charged particles such as protons and alpha particles are classified as
    High LET because these particles are much bulkier in terms of mass than electrons and therefore deposit their energy over much smaller distances in the cell.
  40. Note:
    LET is directly proportional to the square of the charge and inversely proportional to the square of the velocity. Basically as the radiation hits the tissue, it slows down.
  41. What relates the ability of radiations with different LETs delivered under the same conditions to produce the same biological effect? In other words, equal dose of different LET radiations do not produce the same biologic response.
    • RBE relative biologic effectiveness
    • like the tanning bed versus laying out at the beach
  42. Gross structural changes in chromosomes are called
    aberations, lesions, or anomalies.
  43. Structural changes induced in chromosomes by radiation include single breaks, multiple breaks, and a phenomenon known as
    chromosome stickiness or clumping.
  44. Radiation is an effiecient breaker of chromosomes by
    indirect or direct pathways.
  45. A ________ ________ occurs when radiation is administered to cells in the G1 phase or before the cell replicates its DNA in the S phase.
    chromosome aberation and can invovled both daughter cells after mitosis, because if the break is not repaired, the cell replicates it during the S phase.
  46. A _______ ________ results when radiation is administered to cells in the G2 phase or after they have completed DNA synthesis.
    chromatid abberation
  47. When any part of the chromosome results in 2 chromosome fragments where 1 fragment contains the centromere and the other (acentric) does not.
    Single radiation induced break
  48. The rejoining of the fragments from the single radiation induced break is______ and has a high probability of occurring because of their proximity.
  49. If irradiation occurs in _______ cells and restitution does not occur, both fragments are replicated during the S phase thus resulting in 4 fragments (each with a broken end)
  50. When radiation interacts with a cell, the ionizations are ________ or___________
    direct or indirect
  51. Ionizing radiation can be classified as
    electromagnetic or particulate
  52. When a beam of charged particles (alpha, protons, or electrons) is incident on living tissue, _____ _____ of a critical target, DNA, is highly probable because of the relatively densely ionizing nature of most particulate radiations.
    direct ionization
  53. What predominates when neutrons compose the primary beam because the secondary particles produced (protons, alpha, or heavy nuclear fragments) from the neutron's interaction with the nucleus of the atom may cause damage directly to the DNA or toher important macromolecules in the cell.
    Direct effects
  54. What predominates when the incident beam is composed of xrays, gamma rays or neutrons?
    indirect effect
  55. what occurs predominantly when xrays or gamma rays compose the primary beam, thus producing fast electrons as the secondary particles that interact with the most abundant cellular medium?
    indirect effect
  56. Indirect effect involves a series of reactions knowns as_________
    radiolysis or splitting of water.
  57. what is a highly reactive species with an unpaired valence electron?
    free radical
  58. A _____ ______ may involve both daughter cells after mitosis, because if the break is not repaired, the cell replicates it during the S phase.
    Chromosome aberration
  59. approximately ______ of all single breaks heal by _____ with the result being no damage to the cell.
    • 95%
    • restitution
  60. 2 chromatids that each contain a centromere that join are called
  61. 2 chromatids that join without a centromere are
  62. A ____ _____ in 1 chromatid in 2 different chromosomes also produce 4 fragments, 2 contain a centromere but 2 do not
    single break
  63. When an acentric fragment from 1 broken chromosome joins to a centromere containing fragment of the other broken chromosome and forms a normal appearing chromosome this rearrangement is called
  64. A ____ _____ in one arm of the chromosome results in 3 fragments, each with a broken end
    double break
  65. The major consequences of a double break are
    deletions and inversions
  66. When the fragment between the  break is lost and the remaining 2 fragments join, it is called
    deletion. Kind of like cutting your body in 3rds and removing your torso and putting your head and legs together.
  67. When the middle fragment with 2 broken ends turns around or inverts before rejoining the other 2 fragments, this is called
    inversion. Kind of like cutting your body in 3rds and taking your torso and turning it upside down before connecting it to back to your head and legs.
  68. The # of _____ ______ is directly proportional to the total dose of radiation administered.
    single breaks
  69. The frequency of single breaks, or simple aberrations also increases as the _____ of the radiation decreases.
  70. _____ LET radiations such as xrays and gamma rays produce a higher amt of simple versus complex (multiple breaks) aberrations.
  71. Puck and Marcus first irradiated
    human cervical carcinoma in a petri dish
  72. The response of cells after irradiation can now be classified into 3 categories....
    division delay, interphase death, or reproductive failure.
  73. Note
    Puck and Marcus created the survival curve
  74. The line of cervical carcinoma cells that have been used since the 1950s are called
    HeLa cells
  75. The measure for the proliferation status of a cell population. The ratio of the number of mitotic cells to the total # of cells in the irradiated population
    Mitotic index
  76. Irradiated cells that involve a disruption in the mitotic index is known as the
    division delay
  77. Division delay causes cells in interphase at the time of irradiation to be delayed in the _____ phase which is also known as mitotic delay.
  78. Note
    the consequence of mitotic delay is a decrease in the MI for the population, which means that fewer cells than normal will enter mitosis and divide.
  79. The higher the radiation dose, the longer is the ______ and therefore the greater is the decrease in the mitotic index
    mitotic delay
  80. the results in a higher than normal # of cells dividing is
    mitotic overshoot
  81. Cells attempt to repair radiation damage before mitosis by stopping in ________phase to confirm that the DNA and protiens are intact.
  82. Does division delay occur in both lethally and nonlethally damaged cells?
  83. If irradiation of the cell during the G1, S, or G2 phase results in death, this mode of response is
    interphase death
  84. Interphase death is defined as
    death of an irradiated cell before the cell reached mitosis., also known as nonmitotic or nondivision death.
  85. VIM
    vegitative intermitotic
  86. DIM
    differentiating intermitotic
  87. RPM
    reverting postmiotic
  88. FPM
    fixed postmiotic
  89. The 3rd and most common end point for response of cells to radiation is _____ which is defined as a decrease in the reproductive integrity or cells ability to undergo a limited # of divisions after irradiation.
    reproductive failure aka mitotic death.
  90. Another form of cell death that has been assoc with the cellular response to radiation and is unrelated to mitosis because it is not an unsuccessful attempt by the cell to divide is _____
  91. The most common way of evaluating the cellular response to radiation that was first introduced by Puck and Marcus when they irradiated the human cervial cells (known as HeLa cells) on a semilogarthmic graph. The results were called a
    survival curve
  92. A plot of the radiation dose administered on the x axis versus the surviving fraction of cells on the y axis
    survival curve
  93. The survival curve is characteristic of the survival of cells exposed to ____ LET radiations such as ____ or _____
    • low
    • xray or gamma rays
  94. As the radiation does increases, the probability of cellular targets being hit _____
    also increases.
  95. 3 important parameters that allow interpretation of survival curves are the
    • extrapolation #
    • quasithreshold dose Dq
    • dose Do
  96. survival curve low let means
    cell has to have multiple hits to kill
  97. note
    radiosensitive cells have a low Do whereas radioresistant cells have a high Do.
  98. Changes in response to radiation is
    conditional sensitivity
  99. 3 factors of conditional sensitivity are
    physical, chemical, and biologic
  100. what can affect cellular radioresponse and therefore change the overall appearance of a cell lines survival curve and magnitude of the parameteres?
    • The 3 group factors of conditional sensitivity
    • physical
    • chemical
    • biologic
  101. what is an example of a physical factor that influences cellular radioresponse
    the response of cells to high LET radiation differs from that seen after exposure to low LET radiation and that is because the high LET goes straight and hard and the cells gets all of its energy whereas low LET bounces around. Pg 64
  102. What are the 2 physical factors that influence cellular response to radiation?
    dose rate. The amt of radiation put in the cell. and the response of cells to high LET radiation differs from that seen after exposure to low LET radiation
  103. A____ _____ has been observed for reproductive failure, division delay, chromosome aberrations, and survival time after whole body irradiation.
    dose rate
  104. The ___ ___ is significant with Low LET radiations such as xrays and gamma rays but is not observed with high LET
    dose rate effect
  105. what are 2 major chemical factors that influence cellular response to radiation
    radiosensitizers and radioprotectors
  106. which chemical enhances repsonse to radiation?
  107. which chemical decreases the cellular response to radiation?
  108. What is the most potent radiosensitizer
  109. Note
    cell survival curves differ for oxic (normal oxygen level) versus hypoxic (reduced oxygen level) cell populations.
  110. the magnitude of the oxygen effect is called
    OER oxygen enhancement ratio
  111. What compares the response of cells with radiation in the presence and absense of oxygen
  112. what do hypoxic cell sensitizers do
    they selectively increase the radiosensitivity of hypoxic tumor cells.
  113. The ability of a radioprotector to diminish the effects of a dose of radiation is called
    dose reduction factor DRF
  114. What are some examples of radioprotectors?
    • sodium cyanide
    • carbon monoxide
    • epinephrine
    • histamine
    • serotonin
  115. Why are the  below radioprotectors
    sodium cyanide, carbon monoxide, epinephrine, histamine, and serotonin
    Because they all cause hypoxia is cells.
  116. what are 2 biological factors by which cellular response is also affected by
    position in the cell cycle and the ability to repair sublethal damage
  117. Is cellular radiosensitivity dependent on the specific phase of the cell cycle during irradation?
    yes most cells are the most sensitive in the G2 and M phase and most resistant in the S phase
  118. when are cells the most radiosensitive?
    G2 and M
  119. When are cells the least radiosensitve
    S phase
  120. What states that that ionizing radiation is more effective against cells that are actively mitotic, are undifferentiated, and have a long mitotic future?
    The law of Bergonie and Tribondeau. It basically states that immature, rapidly dividing cells were damaged at lower radiation doses than matre, nondividing cells.
  121. Bergonie and Tribondeau defined radiosensitivity in terms of the
    mitotic activity and the level of differentiation. These 2 characteristics determined a normal cells sensitivity to radiation therefore cells dividing more often are more radiosensitive than cells dividing less often or not at all.
  122. According to Bergonie and Tribondeau, cells that are undifferentiated ( immature cells whose primary function is to divide and replace more mature cells lost from the population) are extremely radiosensitive. These cells are also known as
    stem or precursor cells.
  123. A fully differentiated cell is know as an
    end cell
  124. The change in sensitivity is know as the
    conditional sensitivity
  125. The 1st group of cell population category  is______ which are cells that are rapidly dividing, undifferentiated cells with short life spans.most radiosensitive examples are basal cells and crypt cells
    vegitative intermiotic cells VIM
  126. The 2nd group of cell population is _______ which are cells that are also actively mitotic but a little more differntiated than VIM cells. these are a radiosensitive group. examples are intermediate spermatogonia and myelocytes
    differntiated intermitotic DIM
  127. The fourth most  group of cell population is _______ which are cells that normally do not divide but are capable of doing so. this group is radioresistant. examples are parenchymal cells of the liver and lymphocytes
    reverting postmitotic RPM
  128. The most radioresistant and th 5th of the cell group population are the _______ which are cells that are highly differentiated, do not divide, and may or may not be replaced when they die. examples are nerve cells and muscle cells
    fixed postmitotic FPM
  129. Response to ionizing radiation treatment refers to
    visible structural and functional changes that a dose produces in a ceratin period.
  130. Response at all levels, whether in a cell, a tissue, an organ or a system or the entire organism is a function of
    the dose administered.
  131. Structural or morphologic response after irradiation is usually grouped into 2 phases
    • early or acute changes observed within 6 months of treatment AND
    • late or chronic changes occurring more than 6 months later
  132. What refers to the replacement of damaged cells by the SAME cell type?
  133. What refers to the replacement of damaged cells by a DIFFERENT cell type, thus resulting in scar formation or fibrosis?
  134. What are the most common early or acute changes after irradiation
    inflammation, edema, and possible hemmorrhaging in the exposed area. if doses are high, these changes can progress to chronic
  135. What are the most common late or chronic changes after irradiation
    fibrosis, atrophy,, and ulceration
  136. note
    Late changes after irradiation are permanent and not reversible
  137. Who summarized the acute and chronic effects of radiation into various categories or grades based on the severity of clinical response
    RTOG, radiation therapy oncology group, they set the standards