|
DNA samples can be analysed
to explore possible paternal
and maternal relationships
between parents and
children. This is possible
because half of each
person's 23 pairs of
chromosomes come from their
mother, and half from their
father. Each of the
chromosomes contains many
sections of non-coding DNA
that does not seem to code
for a protein, but contains
areas called short tandem
repeats (STRs). Each STR
contains repeats of short
sequences of bases, such as
CATG in CATGCATGCATG.
When STRs are tested in
DNA profiling, they occur in
pairs. One chromosome in a
pair carries an STR from the
person's mother, and the
other carries an STR from
the person’s father.
A person’s DNA profile as
seen on an electrophoresis
gel usually shows two lines
for each of the STRs tested.
This is because usually, the
STRs inherited from the
parents are of different
lengths. Occasionally, only
one line appears because
both STRs in a pair are of
the same length.
When the DNA profile of a
child is compared to the
profiles of the child's
genetic parents, it is
possible to match one line
in each STR area with a line
in that area of the mother's
profile. In this way, DNA
profiling can also reveal
non-paternity.
Three or four STRs, of
very different sizes, are
analysed when exploring
family relationships.
DNA profiling in
the media
Elizabeth Hurley, the
British actor and cosmetics
spokesperson, went to court
to prove who the father of
her baby was. The case was
brought to the family court
by her ex-boyfriend,
Hollywood producer Stephen
Bing.
DNA testing proved that
Bing was indeed the father.
This news came at a rather
unfortunate moment, as Bing
was waiting for results from
a DNA test relating to
another paternity case with
a different person. |
