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20 Cards in this Set
- Front
- Back
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Define an isotope? |
They have the same number of protons in the nucleus but a different number of neutrons |
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Define negatron emission. State what nuclei undergo this? |
Loss of an electron from the nucleus when a neutron transformsinto a proton Tritium, Carbon 14, Phosphorus 32 and Sulfur 35 |
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Iodine 125 decays by electron capture. Define this and state what is produced? |
A proton captures an electron and becomes a neutron X-rays |
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Explain briefly how a Geiger counter works? |
Particles enter vacuum tube Ionise gas atoms/molecules Ions strike electrode, causing ions to flow |
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What 2 isotopes cannot be detected by a Geiger Counter? |
Tritium and Carbon 14 |
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Explain briefly how a Scintillation counter works. What can it detect that a Geiger Counter cannot? |
Sample mixed with fluorophore Beta particles cause fluorescent emission, which is measured Tritium and Carbon 14 |
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Explain the process of autoradiography. |
Radioactive labels attached to molecules, which are seperated along gel electrophoresis |
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Define half life. |
Time taken for radioactivity to fall by one half |
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Radioisotopes can be used to investigate metabolic pathways. State 2 advantages of using radioisotopes for this purpose. |
-Very low incorporation required -Fed in trace amounts (doesn't disturb organisms normal metabolism) |
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Radioisotopes can be used to investigate metabolic pathways. State 2 disadvantages of using radioisotopes for this purpose. |
-Compounds tested must be purified to constant specific activity -Site of incorporation must be determined by unambiguous and controlled degradation (tedious and time consuming) |
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State 3 other biological applications of radioisotopes. |
Answe can include any 3 of the following: -Translocation studies -Ecological studies -Assays -Mutagenesis and sterilization |
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Iodine 131 targets what organ? How is Iodine radiation treated? |
Thyroid gland Iodine tablets to displace Iodine 131 |
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In the UK only cooking herbs and spices are subject to irradiation. What is the source? What kind of radiation is emitted? |
Cobalt 60 Gamma rays |
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What is the half life of Tritium? What type of emission does it produce? What is it suitable for? Other notes? |
12.3 years Beta Labelling organic molecules at high specific activity Low efficiency of detection, high rate of exchange with environment |
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What is the half life of Carbon 14? What type of emission does it produce? What is it suitable for? Other notes? |
5715 years Beta Labelling organic molecules Low rate of exchange with the environment and low specific activity |
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What is the half life of Phosphorus 32? What type of emission does it produce? What is it suitable for? Other notes? |
14.3 days Beta Labelling proteins and nucleotides Hazardous and high ease of detection |
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What is the half life of Sulfur 35? What type of emission does it produce? What is it suitable for? Other notes? |
87.2 days Beta Labelling proteins and nucleotides Low isotope effect and low specific activity |
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What is the half life of Iodine 125? What type of emission does it produce? What is it suitable for? Other notes? |
59.9 days Electron Capture and gamma Labelling proteins and nucleotides High specific activity and hazardous |
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State 2 advantages of using fluorescence over radiochemical. Also, state a disadvantage of using fluorescence. |
Advantages can include: -Very sensitive: single molecule detection possible -No extra hazard -Extra information on molecular interactions Disadvantage: -Addition of fluorophore changes molecular structure |
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State 2 advantages of using radiochemical over fluorescence. Also, state a disadvantage of using radiochemical. |
Advantages: -Very sensitive -No change in structure Disadvantage: -Hazard of radioactivity |
