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SSER Ltd.…read more

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Blood, taken from individuals and from the scenes of crime, is
essential material for the forensic scientist
Blood found at the scenes of crime can be used
for Genetic or DNA fingerprinting
When the DNA fingerprints of such blood samples are compared with those of
suspects, the identification of criminals may be established
Forensic scientists also use blood samples to determine blood groups
Blood groups are another means of identifying individuals involved in crime
Identifying blood groups and obtaining genetic fingerprints are also useful
measures for establishing the identity of the father in paternity disputes
Different components of whole blood are used for the
different procedures described above…read more

Slide 3

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Blood is a tissue composed of red cells, white cells and
platelets suspended in a fluid matrix called the plasma
white cells
red cells
White cells possess nuclei and hence contain molecules of DNA
Red cells lack nuclei and therefore do not contain molecules of DNA…read more

Slide 4

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These red cells lack DNA but possess chemicals
at their cell surfaces that enable us to determine
an individual's blood group
This granulocyte possesses a nucleus containing
the DNA of the individual from whom the blood
sample was taken ­ the DNA in these white cells
can be used to obtain human DNA fingerprints…read more

Slide 5

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In order to understand how individual blood groups can be identified, it is
necessary to have an understanding of how the body's immune system functions
The functioning of the immune system is complex and involves many different
types of white cell
A particular type of white cell, known as the B-lymphocyte responds to
invading `foreign' material by secreting proteins called antibodies into
the body's fluids for destruction of the material
The `foreign material' that triggers this immune response by lymphocytes
is described as an antigen
Antigens are molecules that are recognised as foreign when
introduced into the body and elicit an immune response
Antigens are usually proteins, glycoproteins or large polysaccharides
Antigens are usually located on the membranes and walls
of cells
Bacterial cells, cancer cells, and the cells of disease-causing
organisms all have antigens that allow the body to recognise them
as foreign…read more

Slide 6

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Mature B-lymphocytes
differentiate from stem
cells in the bone marrow
Mature B-lymphocyte
The mature B cells migrate via the blood to
lymphatic tissues such as the lymph nodes,
the tonsils and the spleen
This mature lymphocyte can be recognised by its large,
spherical nucleus that occupies at least
90% of the cell's volume…read more

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