Transcript Multiple Allele Inheritance

Multiple Allele Inheritance
(Blood Types)
Multiple Allele Inheritance:
• There are more than two alleles for a
trait. Organisms still only inherit two of
them, but there is a greater variety of
genotypes and phenotypes.
Example:
Rabbit
coats.
Giant Rabbits
ABO Blood groups
The result of Multiple allele inheritance
(as well as complete dominance).
A History of Transfusions
Blood transfusion is the process of transferring blood
or blood-based products from one person into the
circulatory system of another. Blood transfusions can be
life-saving in some situations, such as massive blood
loss due to trauma, or can be used to replace blood lost
during surgery. Blood transfusions may also be used to
treat a severe anaemia or conditions caused by blood
diseases.
1818, Dr. James Blundell
Dr. James Blundell, a British obstetrician, first
experimented with blood transfusions in dogs, and
completed his first successful human transfusion in
1818. He completed four successful transfusions out of
slightly more than twice this number.
Blundell’s first successful transfusion of human
blood was for the treatment of postpartum
hemorrhage. He used the patient's husband as a
donor, and extracted four ounces of blood from
his arm to transfuse into his wife.
Karl Landsteiner
(early 1900s)
In 1909, Landsteiner classified the blood of human
beings into the now well-known A, B, AB, and O
groups and showed that transfusions between
individuals of groups A or B do not result in the
destruction of new blood cells and that this
catastrophe occurs only when a person is
transfused with the blood of a person belonging
to a different group. (He had suggested that, because the
characteristics which determine the blood groups are inherited, the
blood groups may be used to decide instances of doubtful paternity.)
Dr. Richard Lewisohn,
(1915)
Dr. Richard Lewisohn, at New York's
Mount Sinai Hospital, formulates the
optimum concentration of sodium citrate
that can be mixed with donor blood to
prevent coagulation, but pose no danger
to the recipient -- .2 percent. (Isotonic to
blood)
Agglutination
If you are given the wrong blood type,
agglutination can occur, which may result
in clumping of cells. This may result in
death.
Testing for Blood Types
• Add a drop of anti-A antibodies (left) to blood drop A
Add drop of anti-B antibodies (right) to blood drop B
• See If Drop A and Drop B Are Clumped By
Antibodies [Phenotype Percentages Based On U.S.
Population]
• Type O (45%): No clumping for either
blood drops with anti-A or anti-B
antibodies
• Type A (42%): Clumping for blood drop with
anti-A antibodies
• Type B (10%): Clumping in blood drop
with anti-B antibodies
• Type AB (4%): Clumping for both blood
drops A and B for anti-A and anti-B
antibodies.
The Rh factor
Rh factor
The Rh blood group is determined by
a single gene with two alleles positive
and negative.
Rh stands for “Rhesus factor” because
it was discovered in rhesus monkeys.
The positive allele Rh+ is dominant, so persons
who are Rh+ Rh+, or Rh+ Rh-, both have positive
Rh factors. Individuals with Rh- Rh- alleles negative.
Rh incompatibility
Rh incompatibility occurs when the mother's blood
type is Rh negative and her fetus's blood type is Rh
positive. An alternative name is Rh disease.
If a pregnant woman is Rh negative and the baby's
father is Rh positive, then the baby may inherit the
father's blood type, creating incompatibility between
the mother and the fetus.
With Rh incompatibility, if some of the fetal blood gets
into the mother’s blood stream, and her body will
produce antibodies. These antibodies could pass back
through the placenta and harm the developing baby's
red blood cells, causing very mild to very serious
anemia in the fetus. The first baby is usually safe,
because fetal and maternal blood usually do not mix
until delivery.
• If the second baby is also Rh positive,
there's a risk that the mother’s antibodies
will attack the baby’s blood cells and
cause problems.
Treatments
Rh disease is rare today, because mothers who are
Rh negative receive injections with a drug called
Rhogam. Rhogam removes Rh positive fetal cells from
the mother's blood stream before her body recognizes
them and begins making antibodies. All mothers who
are Rh negative receive a shot of Rhogam at 28
weeks.
(If antibodies are present and anemia is detected in the
fetus, a blood transfusion is performed to replace the
fetus's blood supply with Rh-negative blood, which will
not be damaged by antibodies the mother’s immune
system has created.)