RadBio 9/28 1st test Katy

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RadBio 9/28 1st test Katy
2012-09-27 23:05:46
radiobiology radiation therapy oncology

Rad Bio 1st Test
Show Answers:

  1. DNA s the material from which __________ are made.
  2. Individual genes are  assigned specific loci(or positions) on protein structures called___________.
  3. The cell contains several nucleoli which are organelles that facillitate________asssembly.
  4. Woven throughout the cytoplasm is a filamentous membrane called the _____________.
    endoplasmic reticulum.
  5. The endoplasmic reticulum is continous with the___________and houses the_____________.

    nuclear membrane, ribosomes
  6. Between he nucleus and the cell wall  is as substance
    called_________ made from__________and_________.

    cytoplasm, cytosol, extranuclear organelles
  7. Which organelle is responsible for protein synthesis?
  8. Which organelle stores and manages intracellular substances?

    Golgi apparatus
  9. This organelle  is important for intracellular
  10. ___________are organelles that harbor specific enzyme systems which facilitate certain metabolic processes.
  11. Which organelle produces ATP?
  12. ___________function in cytoplasmic storage
  13. ____________is the source of energy that drives intracellular metabolism.
  14. What are the four phases of the cell cycle?
    G1, S, G2, Mitosis

    • *note
    • (G0  is the resting phase and occurs outside of the four phases -Scott called it the "pit stop of the cell cycle")

  15. ______is the period before duplication or synthesis of DNA in the nucleus.
  16. In the______ ______,living cells are fully functioning but not programmed for mitosis.
    GO, phase
  17. The_____  _____  is the observable sequence of events pursued during the life span of a dividing cell.
    cell cycle
  18. The_________ phase is extremely variable in length.
  19. The________phase is the period in which nuclear DNA is synthesized and chromosomes are duplicated.
  20. During_________phase, the cell is growing, producing proteins and organelles and discharging it's metabolic responsibilities
  21. The shortest phase of the cell cycle is the___________ phase.
    M phase(mitosis)
  22. Radiation is most effective during the ______phase.
  23. DNA is composed of a series of _________.
  24. Deoxyribonucleotides,
    which are the building blocks of ________  are composed of three chemical
     Deoxyribonucleotides, which are the building blocks of ________  are composed of three chemical components: _________, ________, and __________.

    • DNA
    • 1)a phosphate group
    • 2)deoxribose or ribose(5 carbon sugar)  depending on whetherit's DNA or RNA  
    • The phophate group and the sugars(deoxribose or ribose)make up the sides of the ladder.
    • 3) a nitrogenous base  ("rungs of the ladder" A,T, C, G)

  25. As long as cells can maintain themselves in  a range of normal function, they exist in a state of _____________.
  26. Cells maintain themselves in a state of homeostasis by elaborating a vast array of_______ and _________ that facilitate adaption to physiologic and pathologic stress.
    proteins ,macromolecules

    *remember these are made in the ribosomes
  27. What are the phases of mitosis?
    prophase, metaphase, anaphase, telophase

    *(PMAT..I  remember this by thinking pee mat and imaging my dog peeeing on a doormat.{Sorry is that's gross but gross or funny stuff is easier to remember!!)
  28. Initially tumor growth is exponential, but as the tumor enlarges and outgrows it's blood supply the rate of cell replication more closely equals the rate of cell______.
    This is demonstrated by the ________growth curve.
    Tumors that are detetectable are usually in the _______ portion of the curve.Treatment reduces the number of cells, thus moving the tumor back down the curve where growth rate is_______.Once this has happened,the cells are ____   ______ and are _______ ________ to radiation and chemotherapy.
    death, Gompertzian, higher, higher, rapidily dividing, more sensitive
  29. The DNA nitrogenous base adenine can combine only with________

    • *pneumonic: All Tigers Can Growl
    •   they're in order: A combines with T
    •                                combines with G)
  30. The DNA nitrogenous base guanine can only combine with_______.
  31. During__________the chromsomes shorten. The chromosomes consist of two chromatids atached at centromere.Centrioles move to opposite poles of cell;spindle fibers appear and begin to orient between poles; nucleoli and nuclear membrane dsappears.
  32. Chromosomes line up in the middle in of the cell in ___________.
  33. The two sister chromatids are detached and pulled towards opposite ends of the cell during ____________.
  34. This phase is the reverse of prophase:new chromosomes begin to elongate,nuclear envelopes reappears and spindle fibers disapear.
  35. Identify this phase of mitosis:
  36. Identify this stage of mitosis:
  37. Identify this stage of mitosis:
  38. Identify this stage of mitosis:
  39. _________  __________ or ___________ can be defined as the study of the sequence of events following the _______of energy from __________ __________ , the effort of the organism to _________, and the damage to the organism that may be produced.
    Radiation biology, radiobiology ,absorption, ionizing radiations, compensate
  40. When discussing the interaction of radiation with matter, two terms must be decribed:________, and ________.
    ionization, excitation
  41. In _________ the incoming radiation ejects an _______
    from the shell of an atom, causing the atom to be charged or __________.
    ionization, electron, ionized
  42. In _________, the ________ in the outer shell is said to be _________(or oscillating) but is not ejected from the shell.
    excitation, electron, excitated
  43. Can visible changes from radiation usually be distinguished from other kinds of trauma?
    No (the only exception is radiation induced cataracts)
  44. Radiation ______ or _______ _____ interact with a cell.
    may, may not
  45. If interaction does occur, damage _______ or ______ ______ occur.
    may, may not
  46. The __________ energy deposition occurs _______
    ___________ and is ______________.
    initial, extremely  rapidly, nonselective

    • *in other words-the intial energy deposited from the radiation happens really fast, but it does not choose specific areas of the cell.
  47. Biologic changes that occur after irradiation do so after some time has elapsed. This is called the ________
    latent period
  48. The duration of the latent period is ___________ related to the _________ administered and can range from ______
    to ____________.
    inversely,dose, minutes, years

    *in other words: A very large dose would have a very short latent period/small dose a long latent period Imagine people in a nuclear disaster: as people get further and further away from the source of the radiation spill(as the dose gets lower) the latent period gets longer and longer until  you get far enough away that it will be many years down the road after a long latent period you will have people coming up with thyroid cancer etc.
    (read about Chernobyl)
  49. Ionizing radiations are classified as either ____________
    or ___________.
    electromagnetic, particulate
  50. Examples of electromagnetic radiation:
    x-rays, gamma rays
  51. Examples of particulate radiation:
    alpha, beta, electrons

    • *Particulate radiation is tiny fast-moving particles that have both energy and mass.(electromagmetic radiation has no mass)Particulate radiation is primarily produced by disintegration of an unstable atom.  
  52. When radiation initially interacts with a cell, the ionization can be _____________ or ______________.
    direct, indirect
  53. Directly and Indirectly ionizing radiation:

    Note: this is just and image for your understanding
  54. _________ ionizing radiations give rise to ____________,
    charged secondary particles that can then directly or indirectly cause ionizations in the critical ________.
    Indirectly, fast(high energy), target
  55. In indirect effects ____________ __________, as the secondary particles , react with the most abundant cellular medium,___________.
    fast electrons, water
  56. __________ ________ involve a series of reactions known as _____________.
    Indirect effects, hydrolysis
  57. describe low LET radiation:
    • x rays and gamma rays
    • indirectly ionizing
    • short wavelength, high energy waves
    • sparsely ionizing
    • randomly interact
    • do not give up energy quickly
    • indirect effects- free radicals are formed  through radiolysis
    • may cause single-strand breaks in one side of the DNA ladder
    • usually sublethal- repair enzymes reverse the damage
  58. What does LET stand for?
    linear energy transfer
  59. X-rays and gamma rays are ________ LET radiation.
  60. Alpha, beta, and neutron particles have predominately
    _______________ effects.

    • *note-
    • (alpha, beta, neutrons)
    • Direct Effects
    • High LET
    • has MASS

    • Xrays, gamma rays
    • Indirect Effects(Hydrolysis>free radicals)
    • Low LET
    •  NO MASS
  61. A reactive atom or atom group in a highly reactive transient state because it has unpaired valence electron is called a __________.
    free radical

  62. One  very toxic substance to the cell, ____________, can be formed as a consequence of ________ when is  two  _______ ________combine.
    hydrogen peroxide, hydrolysis, free radicals
  63. Because the majority of the cell is(____%) consists of ______, the probability of damage by _____ effects is much greater than _______effects with the use of ________ _________.
    80, water, indirect, direct, ionizing radiation.

    *this is true because indirect effects involve radiolysis(which is the splitting of water which is 80% of the cell)
  64. Of the  several reactions caused by indirect effects, the predominate pathway that accounts for approximately _______ of the cellular damage involves the _________ _____________.
    2/3, hydroxyl(OH•), radical
  65. A _______ _______ contains an ________ electron in the outer shell; this makes it highly _______.
    free radical, unpaired, reactive
  66. Depending on the composition of the incident beam of the radiation, various _________ particles are produced in the cell. These __________particles may ________ or ________ ionize the______ target.The physical properties of these ____________ particles(mass and______)give rise to the characteristic path of damage in the cell.
    secondary, secondary,directly, indirectly,critical, secondary, charge
  67. The rate at which energy is deposited by charged particles(incident or secondary)as they travel through matter is known as the ______ ______ ______(___)
    linear energy transfer, LET
  68. The ______ is an average value calculated by dividing the ____________ deposited(in __________) by the distance traveled in _______.
    LET, energy, keV, µm
  69. Sparsely ionizing radiation like ____ ___and_____ _____ are classified as _____ _______because the _________ electrons produced are small particles that deposit their energy over _______   ________in ___________.
    xrays, gamma rays, low LET, great distances, tissue
  70. _______ ionizing radiation like ______ and _______
    particles are classified as _____ _______ because these particles are much bulkier in terms of ______than _______and therefor  deposit their energy over much
    _______ distances in the cell.
    • densely, protons, alpha high LET, mass, electrons, smaller
  71. LET  is _________ proportional to the square of the _______________ and ___________ proportional to the square of the _________.
    directly, charge(Q), inversely,  velocity

  72. Generally, a large charged particle like a ______ or  a _______ particle does not penetrate nearly as far as a ______ _______ particle(_________) , and not quite as far as am uncharged particle of equal mass.(______)
    alpha, proton, , smaller charged , electron, neutron
  73. _________ usually have an intermediate LET. As the neutron's energy _____ it's penetration into tissue also _______therefore, it's LET  _________.
    neutrons, increases,  decreases
  74. Equal doses of different _______ radiations do not produce the same biologic effect. This is called the _____ _______
    • LET, relative biologic effectiveness
    • different dosages of radiations of different LETs are required to achieve the same biologic effect.

     ******* ANALOGY ALERT**********

    • It's kind of like comparing the  Children's Liquid Tylenol with Infant's Tylenol (The childrens liquid is *33 mg/ml and  infants is *99 mg/ml)  The infants formula is 3 times more concentrated than the children's formula.(Infant's Tylenol RBE = 3) If we use  the Children's Tylenol as the  standard to compare against(like the 250 keV xray) and then divide it by the infant tylenol(like the test radiation in the RBE equation)    Dose for Children's Tylenol for 99 mg(3 ml)/Dose of Infants Tylenol to get the same benefit  (1 ml)
    • RBE(0f Infants tylenol)=3
    • (actually 32 mg/ml and 100mg/ml but the math doesn't work out as neat so I fudged a litle)
  75. The formula for determining the relative biologic effectiveness of a test radiation is:
    • RBE of test radiation=Dose from 250 keV x-ray
    •                                        Dose from test radiation to
    •                               produce the same biologic effect
  76. In general, as the LET of the radiation increases , so does its  ________.
  77. The key molecule in the nucleus of the cell for radiation damage is thought to be __________.
  78. The ______ theory states that when ionizing radiation interacts with or near a key molecule(____), the _____ area is termed the _______.
    target, DNA, sensitive, target.
  79. Damage to a key molecule may be lethal and has led to the development of the _______ ________ for radiation _______.
    target theory, damage

    *key molecule here is DNA
  80. An ionization event that occurs in the target is termed a ______.
  81. One form of DNA damage involves  the change in or loss of one or more of the four nitrogenous base(adenine, guanine,_______,   _________, or  ________instead of _______).
    thymine, cytosine or uracil, thymine

    *in the book the sides of the ladder-the alternating sugar groups is phosphate groups are referred to as the backbone
  82. ______ ________ breaks are more common in the DNA backbone, which are common after irradiation with ______ ______ radiations, and may or may not be ____________.
    Single strand, Low LET,repaired
  83. Irradiated cells that involve a disruption in the _______ ______ (____), the ratio of the number of mitotic cells to the total number of cells in the irradiated population.
    mitotic index, MI.
  84. The higher the radiation dose, the longer is the mitotic delay and therefore the greater is the decrease in __________.
    MI(mitotic index)
  85. Smile  the test will be over soon!
  86. A change in the base sequence(in DNA) not rectified by the cell is an example of a__________.
  87. Agents such as ________   ______that that cause change in the genetic  material are  __________.
    ionizing radiation, mutagenic
  88. Gross structural changes in chromosomes are referred to as
    _______, _________, and __________.
    aberrations, lesions, anomolies
  89. What is the difference between a chromoome aberration and a chromatid aberration?
    A chromosome aberration occurs in G1 before the chromosomes have had a chance to replicate and a chromotid aberration occurs in G2 or after the cells have completed DNA synthesis.
  90. In a _______ abberation only one of the two daughter cells will be affected by the chromosme damage if it is not repaired.
  91. With a ________ aberration, if the break is not repaired, it will be replicated in S phase when the cell duplicates it's DNA, and both daughter cells will have the break.
  92. What is the most potent radiosensitizer?
    • oxygen
  93. Consequences of structural damage to  a chromosome  may include_________ with no damage  or_______ or _________ of genetic material.
    healing, loss, rearrangement
  94. A single radiation induced break in any part of a chromosome results in two fragments: the part without the _________ is called the ________ _________.
    • acentric fragment
  95. The rejoining of single break fragments, called _______. and has a probability of ________ of occuring because of their proximity.
    restitution, 95
  96. If restitution does not occur after a single break, both fragments will be replicated in_______ phase resulting in ________ fragments , each with a _______ _____. ______ of these chromatids comtain a ________ and ________ do not. The two ________ containing chromatids join making a ________ fragment and the other two fragments join to make an ______ fragment. This results in an _______ bridge that tears  and results in unequal transmission of genetic material to eah daughter cell.
    • S, 4, broken end, 2, centromere, 2,  centromere, dicentric, acentric, anaphase
  97. When an acentric fragment from one broken chromosome joins to a centromere containing fragment of the other
    broken chromosome and forms a normal appearing chromosome this rearrangement is called a _______.
    • translocation
    • ----------------SINGLE BREAKS---------------------------
    • translocation:part of one chromosome breaks off (single break) and attaches to another .
    • ----------------DOUBLE BREAKS--------------------------
    • deletion:  a fragment between two breaks is lost
    • inversion: a middle fragment in a double break inverts

  98. A ____ _____ in one arm of the chromosome results in 3 fragments, each with a broken end. The major consequences of a double break are
    double break,deletions and invertions
  99. When the fragment between the  break is lost and the remaining 2 fragments joined, it is called a ________.
  100. When the middle fragment with 2 broken ends turns around or inverts before rejoining the other 2 fragments, this is called an _________.
  101. The number of _____ ______ is directly proportional to the total dose of radiation administered.
    single breaks
  102. The number of single breaks is directly proportional to the
    total dose of _________.
  103. What are the three responses described by Puck and Marcus that cells have to radiation?

    Careful here: this is not aking for conditions that affect the cells response to radiation- It IS asking for the cells response to radiation
    • 1.division delay,
    • 2. interphase death
    • 3. reproductive failure

    • (cells Do It with Radiation)
  104. The frequency of single breaks, or simple aberrations ________ as the _______ decreases.
    increases, decreases

    • *Low LET radiation(xrays, and gamma rays) produce a higher amount of SIMPLE(single) versus complex(multiple) breaks.
    • X-rays and gamma rays→Single Breaks

  105. What are HeLa cells?
    HeLa cells are the first immortal cell line, or a cell line that continues to reproduce and "live" outside the human body. These cells have been used in cell research in projects that have benefited mankind around the world. The original cells were taken from cancerous cervical .tumor from a poor African-American woman named Henrietta Lacks who died from cervical cancer in 1951.
  106. Who where Puck and Marcus?
    Puck and Marcus used HeLa cells to study the the effects of radiation.
  107. Who evented the survival curve?
    Puck and Marcus
  108. A plot of the ________ ______ _________on the x axis
    versus the _______ _________of cells on the y axis
    radiation dose administered, surviving fraction
  109. ______    ________can be defined as death of irradiated cells before they reach mitosis.
    Interphase death

    • *note interphase death IS NOT the primary mode of response to radiation.
  110. Nonmitotic and nondivision death are names for
    _________ _________.
    interphase death
  111. If irradiation of the cell during the ___, ___, or ___ phase
    results in death, this mode of response is ___________.
    • G1,S, G2, interphase death
  112. The ratio of the number of________to the total number of cells in the irradiated population is called the _________.
    mitotic cells, mitotic index(MI)
  113. What is an index that gives you the proliferation status of an irradiated cell population?
    mitotic index
  114. When there is a disruption in the MI  of an irradiated cell population it is known as a _______ _____ or a ________ _________.
    division delay, mitotic delay
  115. The consequence of mitotic delay is a decrease in the MI for the population, which means that fewer cells than normal will enter _______and________.
    mitosis, divide
  116. 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 __________.
  117. Two chromatids that each contain a centromere that join are called ___________.
  118. Two chromatids that join without a centromere are _____.
  119. What are the most common late or _______changes after
    chronic, fibrosis, atrophy, and ulceration
  120. What are the most common early or _____changes after
    acute, inflammation, edema, and possible bleeding in the exposed area
  121. The Law of Bergonie & Tribondeau states the ionizing radiation  is more effective against cells that are (1)_______(2) are    _______, and (3 ___________.
    • 1) actively mitotic
    • 2) undifferentiated
    • 3)have a long mitotic future

    • *Note-Initially when tumors are usually found, tumor growth is exponential, but as the tumor enlarges and
    • outgrows it's blood supply the rate of cell replication more closely equals the rate of cell death.(which would make the tumor not sensitive to radiation)This is demonstrated by the Gompertzian growth curve.Tumors
    • that are detectible are usually in the later portion of the
    • curve.Treatment reduces the number of cells, thus moving the tumor back down the curve where growth rate is faster .Once this has happened,the
    • cells are actively dividing and are more sensitive to radiation again.
  122. Bergonie & Tribondeau defined ______ in terms of mitotic activity and the level of differentiation.
  123. Cells dividing more often are more __________.

  124. ________  cells  also known as ______cells are completely undifferentiated and are extremely ________________.
    Stem, precursor, radiosensitive
  125. _______ refers to the replacement of damaged cells by a
    different cell type, thus resulting in scar formation or fibrosis
  126. Ancel and Vitemberger proposed that various external factors influence cellular response to radiation .This is known as________ ________ and  there are three groups of factors: _______,________. and _________.
    • conditional sensitivity, physical, chemical, biologic
  127. ________  is replacing of damaged cells by
    the same cell type

  128. Cells attempt to repair radiation damage before mitosis by stopping in ________phase to confirm that the DNA and proteins are intact.
  129. Does division delay occur in both lethally and nonlethally damaged cells?
  130. VIM is short for ______.
    vegitative intermitotic
  131. DIM is short for ______.
    differentiating intermitotic
  132. RPM is short for _______.
    reverting postmiotic
  133. FPM stands for ________.
    fixed postmiotic
  134. The 2nd group of cell population is _______ which are cells that are also actively mitotic but a little more differntiated than VIM cells. They are also considered radiosensitive.
    • DIM. 
    • examples: intermediate spermatogonia, myelocytes
  135. The 1st group of cell population category  is______ which are cells that are rapidly dividing, undifferentiated cells with short life spans which are the most ___________.
    • Vegitative intermiotic (VIM), most radiosensitive
    • examples: basal cells and crypt cells, type A spermatagonia, erythroblasts
  136. The third group of cells ,known as _______ ________  ________ __________, is intermediate in radiosensitivity.
    They divide_________ nd are more differentiated than VIM and DIM cells.
    multipotential connective tissue cellls, irregularly

    examples:endothelial cells of blood vessels, and fibroblasts of connective tissue
  137. The fourth group of cell population is _______ which are cells that normally do not divide but are capable of doing so. This group is__________.
    reverting postmitotic(RPM), radioresistant

    examples:parenchymal cells of the liver and lymphocytes
  138. The 5th  cell group  is called the ______population. The cells are highly ________, highly differentiated, do not ______, and may or may not be replaced when they die.
    fixed postmitotic (FPM), radioresistant, divide

    • examples: nerve cells and muscle cells
  139. Structurally, organs are composed of two compartments: the __________ and the ___________. The ________ contains the charecteristic cells of that tissue or organ.
    VIM, DIM, RPM,  and FPM cells are example of
    __________ cells.
    parenchyma, stroma, parenchyma, parenchymal
  140. The stroma consists of _______ tissue and _______ and is _________ in radiosensitivity.
    connective, vasculature, intermediate
  141. RTOG  stands for ________?
    Radiation Therapy Oncology Group
  142. The RTOG has summarized the  acute and ______ effects
    of radiation into various categoriesor grades based on the ________ of  the clinical response.
    chronic, severity
  143. ______ can occur in any organ and is more likely after higher doses (_______ cGy) that destroy ___________
    cells and make __________ impossible.
    Repair, 1000cGy, parenchymal , regeneration

    • *repair as ooposed to regeneration
  144. Inflammation, edema and possible hemmorrhaging in the exposed area are the most common _______ or ______ changer after irradiation.
    early, acute
  145. Fibrosis, atrophy, and ulceration are the most common ______ or _______ changes and are _______.
    late, chronic , irreversible
  146. The most severe response _____reponse to irradiation is _______ or death.
    late(chronic), necrosis
  147. Are *Type A spermatagonia cells radiosensitive or radioresistant?Are they actively divising? How differentiated? How about the length of their mitotic fuure?

    *don't confuse Type A spermatgonia(a stem cell) with spermatazoa(mature sperm)
    Extremely Radiosensitive,(VIM) actively dividing, undifferientiated, and have a long mitotic future. 

    • This is a great example to think about the Law of Bergonie and Tribondeeau
    • -------ALERT! -----ALERT!--------------------------------
    • DO NOT CONFUSE TYPE A SPERMATAGONIA(it's VIM )       WITH SPERMATAZOA(it's FPM-totally the opposite-radioRESITANT because it is differentiated, no longer dividing)
  148. Are nerve cells and spermatazoa radiosensitive or resistant? Why?
    • radioresistant.
    • They are fixed post mitotic(FPM) which means that they do not divide and are highly differentiated- both of which mak them highly radioresistant
  149. What are the two  physical factors that influence cellular response to radiation?
    • dose rate, LET
  150. The chemical factors that affect a cells response to radiation are _________, __________.
    radiosensitizers, radioprotectors.

    *These are factors of conditional sensitivity
  151. Fractionation works because normal tissue repair________damage between ________(usually
    within hours of each exposure depending on the dose/fraction).The _____portion or the curve repeats(that is where the damage is repaired) bu all other parameters of the survival curve remail the same.
    between factions but the rest of the survival 
    parameters remain the same.
    sub lethal, fractions, Dq
    Physical Factors:.
    1)dose rate (Low dose rates 
    less efficient for producing damage than high dose rate)
    2)Concentration of
    radiation in cell (LET)Optimal LET is 160 keV(higher or lower is not better) 
    Chemical Factors:
    1)RadiosensitizersOXYGEN!(MOST IMPORTANT) more significant with low LET(Halogenated pyrimidines and nitroimidazoles)
    2)RadioprotectorsSULFHYDRYLS(amofostine)more significant with low LET 
     Biologic Factors:
    1)Position in the cell
    cycle(G2, M-most radiosensitive)(S-least
    2)Ability to repair sub-lethal damage

  153. OER stands for_________________.
    oxygen enhancenment rate

    • radiation under hypoxic/anoxic conditions/
    • radiation under oxic conditions to produce the same biologic effect
  154. The oxygen effect is less significant with______ and  may not be observable with ______ _______ radiation.
    neutrons, high, LET
  155. A dose rate effect has been observable for _______, _______,  or_______.
    reproductive failure, division delay, chromosome aberrations
  156. Puck an Marcus identified the three responses of cells to irradiation as being:_______, __________, or __________.
    division delay, interphase death, reproductive failure

    Also related to  response to cellular irradiation
    i is APOPTOSIS(programmed cell death)
  157. What is the most common response of cells to irradiation?
    reproductive failure
  158. A decrease in the reproductive integrity or cells ability to undergo a limited number of divisions after irradiationis called_______.
    reproductive failure

    The most common response
  159. The dose rate effect is sugnificant with low LET radiation like xrays amf gamma rays but it is not observed in ____ ______ radiation.
    high LET
  160. Cell survival curves differ for ______ versus hypoxic cell populations.
  161. The ability of a radioprotector to diminish the effects of  a dose of radiation is called the _____ _______ _______.
    The equation for figuring this our is:
    • dose reduction factor,
    • radiation dose with radioprotector/radiation dose without the radioprotecto to produce the same biologic effect