Describes the principles applications and uses of tracers in biology, the topic is included in kerala University MSc Botany syllabus.

1. PRINCIPLE,USES & Applications of tracers
in biology
Submitted by
Ardra S
P2214003
FMNC kollam

2. TRACERS
Tracers are substances with atomic or nuclear,
physical,chemical or biological properties that
can help to identify, observe or follow the
behaviour of various physical,chemical or
biological processes

3. TRACER
TECHNIQUE
• It is a method by which we can know
the location and quantity of an organic
substance in a cell and when ,where and
how it will change within the cell
precisely

4. PRINCIPLE OF TRACER
• The principle behind the use of tracers is that an atom in a
chemical Compound is replaced by another atom, of the
same chemical element.
• The substituting atom,however ,is a radioactive isotope,
This process is often called radioactive labelling.
• The power of the technique is due to the fact that
radioactive decay is much more energetic than chemical
reaction, Therefore, the radioactive isotope can be present
in low concentration and its presence detected by sensitive
radiation detectors such as Gieger Counters and
Scintillation Counters.

5. Geiger counter :A Geiger counter is an electronic
instrument used for detecting and measuring ionizing
radiation

6. • There are two main ways in which radioactive tracers
are used.
• When a labelled chemical compound undergoes
chemical reaction one or more of the products will
contain the radioactive label. Analysis if what
happens to the radioactive isotope provides detailed
information on the mechanism of the chemical
reaction.
• A radioactive compound is introduced into a living
organism and the radio-isotope provides a mean to
construct an image showing the way in which that
compound and its reaction products are distributed

7. Metabolic Pathway Studies: Radioactive isotopes can be incorporated
into molecules such as glucose, amino acids, or nucleotides. By
tracking the movement and transformation of these labeled
compounds in living organisms, researchers can study metabolic
pathways, including glycolysis, protein synthesis, or DNA replication.
This helps in understanding the flow of energy and molecules within
biological systems.
Radiography and Imaging: In medical and biological imaging,
radioactive tracers are used to visualize and diagnose various
conditions. For instance, in Positron Emission Tomography (PET) scans,
a radioactive tracer is introduced into the body, and detectors
measure the radiation emitted. This allows for the non-invasive
imaging of physiological processes and the detection of diseases like
cancer or neurological disorders.

8. • The tracer principle states that radioactive isotopes have
the same chemical properties as nonradioactive isotopes
of the same element.
• Isotopes of the same element differ only in the number of
neutrons in their atoms which leads to nuclei with
different stabilities.
• Unstable nuclei gain stability by radioactive decay which
lead to different types of radioactivity.
• One type is gamma radiation which is useful in medicine
because it penetrates the body without causing damage
and can then be detected easily

9. PROCEDURE
• The commonly used radio-isotopes have short halflife and so don’t
occur in nature in large amounts.
• They are produced by nuclear reactions. One of the most
important process is absorption of neutron by an atomic nucleus,in
which the mass number of the element concerned increases by 1
for each neutron absorbed. For example
¹³C + n → ¹⁴C
• In this case the atomic mass increases, but the element is
unchanged. Neutron irradiation is performed in a nuclear reactor.
The other main method used to synthesize radio-isotopes is proton
bombardment.
• The proton are accelerated to high energy either in a cyclotron or
a linear accelerator.

11. APPLICATIONS
Contamination
• The common use of radioactive tracers is measuring gas leaks in
industrial operations. If one gas line is not supposed to contaminate
another,it can potentially be difficult to see if the two are mixing.(
gasses are often not visible to human eyes )
• However , if tracers are injected into both lines, detection of tracer
from one line in another is a clear indication of contamination.
• Tracers can also be used as a method of quality control in
hermetically sealed containers. By exposing the container to
radioactive gas and measuring radioactivity inside the container, it
is simple to tell if the container is properly sealed.

13. Irradiation of food
• The radiation emitted by some radioactive substances can be
used to kill microorganisms on a variety of foodstuffs,
extending the shelf life of these products.
• Products such as tomatoes, mushrooms, sprouts, and berries
are irradiated with the emissions from cobalt-60 or cesium-
137.
• This exposure kills a lot of the bacteria that cause spoilage, so
the produce stays fresh longer.
• Eggs and some meat, such as beef, pork, and poultry, can also
be irradiated. Contrary to the belief of some people, irradiation
of food does not make the food itself radioactive.

15. • Plants take up phosphorus-containing compounds from
the soil through their roots.
• By adding a small amount of radioactive phosphorus-32 to
fertiliser and then measuring the rate at which
radioactivity appears in the leaves, it is possible to
calculate the rate of uptake of phosphorus from the soil.
• The information gathered could help plant biologists to
identify plant types that can absorb phosphorus quickly.
These plants may give better yields resulting in more
food or fibre at less expense.
Phosphorus uptake by
plants

16. Pesticide levels
• To measure pesticide levels, a pesticide can be tagged
with a radioisotope such as chlorine-36, and this is
applied to a field of test plants.
• Over a period of time, radioactivity measurements are
made.
• Estimates can then be made about how much
accumulates in the soil, how much is taken up by the
plant and how much is carried off in run-off surface
water.

17. Medical Applications
• Radioactive isotopes have numerous medical
applications—diagnosing and treating illness and
diseases.
• One example of a diagnostic application is using
radioactive iodine-131 to test for thyroid activity.
• The thyroid gland in the neck is one of the few places in
the body with a significant concentration of iodine.
• To evaluate thyroid activity, a measured dose of 131I is
administered to a patient, and the next day a scanner is
used to measure the amount of radioactivity in the thyroid
gland.

18. • The amount of radioactive iodine that collects there is
directly related to the activity of the thyroid, allowing
trained physicians to diagnose both hyperthyroidism
and hypothyroidism.
• Iodine-131 has a half-life of only 8 d, so the potential
for damage due to exposure is minimal.
• Technetium-99 can also be used to test thyroid
function.
• Bones, the heart, the brain, the liver, the lungs, and
many other organs can be imaged in similar ways by
using the appropriate radioactive isotope.

19. Radioactive isotopes with medical applications
Isotope Use
32P
cancer detection and treatment, especially
in eyes and skin
59Fe anemia diagnosis
60Co gamma ray irradiation of tumours
99mTc
brain, thyroid, liver, bone marrow, lung,
heart, and intestinal scanning; blood
volume determination
131I diagnosis and treatment of thyroid function
133Xe lung imaging
B198Au liver disease diagnosis

20. Uses
• Radioactive isotopes are inexpensive, quite
available and very useful in scientific research and
industry.
• Scientist can analyse biological and mechanical
process using small amount of radioactive isotopes
as tracers
• Tracers are used in medicine to study the process of
digestion and the way in which chemicals move
about in the body.

21. • Food containing a tiny amount of a radioactive
isotopes is fed to a patient. The paths of the
tracers in the food are then followed through
the body with a radiation detector.
• Radioactive isotopes can prevent food from
spoilage quickly by killing the microorganisms.
• Radioactive isotopes can also be used to trace
leaks in pipe.

22. • Engineers study automobile engine wear by making
the cylinder walls in the engine radioactive and
measuring particles that wear away with a radiation
detector.
• The shelf life of fresh strawberries is markedly
increased when the food is subjected to gamma rays
from a radioactive source

23. THANK YOU