Rad Bio Exam 1

Front 1

the most radiaosensitive phase of the mammalian cell cycle is

a. G1
b. s phase
c. interphase
d. mitosis

Back 1

mitosis

Front 2

study of the human genome has shown that

a. genes are vary in size and are not equally spaced on the DNA
b. human chromosomes are all the same size
c. the final mRNA is teh same size as the genoic gene in the DNA
d. chromosome translocations are always lethal

Back 2

genes are vary in size and are no equally spaced on the DNA

Front 3

of the clincal benefits of using high energy 6MV X-rays is that

a. absorption of teh X-rays is linear with distance in tissue
b. RBE of 6MeV X-rays is 3.0 compared to Cesium (y) rays (gamma)
c. X-ray absorption is independent on tissue density (Z)
d. 6MeV x-rays have no exit dose after 5cm

Back 3

C.
X-ray absorption is independent on tissue density (Z)

Front 4

in low let radiations the majority of the DNA damage to a cell si due to

Back 4

indirect action of *OH radicals

Front 5

a mammalian cell survival curve with large should indicates

Back 5

the cells can repair sublethal damage very well

Front 6

the shoulder of a standard mamalian cell survival curve can be decreased by:

Back 6

increasing the dose rate from 10cGy/minute to 200cGy/minute

Front 7

for high LET radiations the majority of cell death is due to

Back 7

direct action to the DNA

Front 8

Radiation sensitivity is not dependent on

Back 8

the size of the cell cytoplasm

Front 9

radiation sensitivity is dependent on

Back 9

DNA size and repair capacity
DNA repair
phase of the cell cycle

Front 10

D0 is the radiation dose that reduces cell survival to

Back 10

37% of its previous value one the exponential portion of the survival curve

Front 11

t/f
if SLD is expressed the shoulder of a low LET survival curve is reduced

Back 11

TRUE

Front 12

t/f
The low LET x-ray survival curve for cells in late S phase has no shoulder

Back 12

FALSE

Front 13

t/f
Dicentric and ring chromosome abberations are nonlethal in irradiated cells

Back 13

FALSE

b/c cell can't divide with these aberrations

Front 14

t/f
the biological effects of radiation are faster processes than the initial radiation chemistry that produces the damage

Back 14

FALSE

b/c biological effects could take months to see

Front 15

t/f
protons are indirectly ionizing radiations

Back 15

FALSE

they are charged particles which cause direct hits

Front 16

t/f
chromatid aberrations arise from irradiation given during G2-phase

Back 16

TRUE

Front 17

t/f
the frequency of chromosome aberrations is linear at doses <2Gy

Back 17

FALSE?

Front 18

t/f
the average D0 for normal human fibroblasts is ~125 cGy

Back 18

TRUE

Front 19

two things that support the concept that DNA is the target of radiation-induced reproductive death

Back 19

1. it takes larger dose to kill cell when irradiating cytoplasm than when it hits the DNA

2. chromosomal aberrations are closely related to cell death

Front 20

t/f
cells in G2 phase are able to perform homologous recombinational DNA repair

Back 20

TRUE

Front 21

t/f
the D for bone marrow stem cells is smaller than the Dq for crypt cells

Back 21

TRUE

Front 22

t/f
OER is mostly independent of the survival level at which you do the comparison

Back 22

FALSE

Front 23

t/f
the OER for x-rays is typically 5.0-8.0

Back 23

FALSE (1-5?)

Front 24

t/f
the TD5/5 for the lung depends on the volume irradiated but the TD5/5 for kidney is independent of the volume irradiated

Back 24

FALSE

Front 25

Dq is___

Back 25

zero for pure single exponential survival curves

Front 26

the clinical response of tumors has been shown to correlate with

Back 26

the survival fraction at 2Gy or alpha component of the LQ survival curve

Front 27

if dose rate of low LET increases from 10rad/min to 100rad/min

D0

Back 27

decreases

Front 28

if dose rate of low LET increases from 10rad/min to 100rad/min

cell survival per Gy

Back 28

decreases

Front 29

if dose rate of low LET increases from 10rad/min to 100rad/min

repair of radiation damage

Back 29

decreases

Front 30

if dose rate of low LET increases from 10rad/min to 100rad/min

number of chromosome aberrations produced per Gy

Back 30

increases

Front 31

if dose rate of low LET increases from 10rad/min to 100rad/min

number of initial ionizations per minute induced

Back 31

increases

Front 32

if lymphocytes were irradiated iwth dose of x-rays equal to 4 times the D0 the average number of lethal aberrations per cell would be

Back 32

4

Front 33

a Bcl protein that inhibits apoptosis after x-ray exposure

Back 33

Bcl2

Front 34

the distance that oxygen can diffuse rom a capillary

Back 34

70-100um

Front 35

typical dose to reduce fibroblast survival to 37% of it's inital value

Back 35

D0

Front 36

teh range that RBE can vary in value from

Back 36

????

Front 37

order of radiosensitivity

mammary cells, bone marrow cells, jejunal crypt cells

Back 37

most sensitive=BM
then mammary cells
then crypt cells=least

Front 38

t/f
the small intestine has limited repair capacity

Back 38

FALSE

Front 39

t/f
the oxygen partical pressure of most normal tissues is 2-4mmHg

Back 39

FALSE

Front 40

apoptosis results in swelling and bursting of the cells contents

Back 40

FALSE that necrosis

Front 41

t/f
necrosis dose not require induction of the p21 protein

Back 41

TRUE it just blows up

Front 42

t/f
clinical tumor response is dependent on dose rate but not total dose

Back 42

FALSE depends on both

Front 43

t/f
Tumor reoxygenation occurs over hours to a day

Back 43

TRUE

Front 44

which cyclin regulates teh G1/S checkpoint

Back 44

cyclin D

Front 45

which cyclin regulates the G2/M checkpoint

Back 45

cyclin B

Front 46

which cyclin dependent kinae inhibitor (cdki) is regulated by p53

Back 46

p21

Front 47

When G1 Cyclin/cdk compleses phosphorylate Rb which transcription factor is released

Back 47

E2F2 ???

Front 48

irradiaton with high LET tend to reduce or increase any differences in cell cycle radiosensitivity

Back 48

decrease
because it doesn't repair well at high LET