Download Genotype Phenotype

Blood typing and
genetics
February 8, 2017
Blood Groups
 All cells in the body have genetically-determined
glycoproteins on their surface; the combinations of these
are unique to each individual and are involved in self / nonself recognition
 Some of these proteins are also antigens – they cause an
immune response in individuals that do not posses them
 The proteins (blood factors) that cause the greatest
immune response belong to the ABO and Rh groups.
Antigen – Antibody Reactions
 Antigens are foreign substances that provoke an immune
response, including the release of antibodies that bind to and
attack them
 Where are antigens found?
 Surface of pathogens (e.g. viruses, bacteria, etc.)
 Vaccines (that’s why they work!)
 Allergens (e.g. pollen, dust, etc.)
 Cancer cells (foreign b/c cell has mutated)
 Transplanted tissue / organs
 Antibodies are proteins produced by white blood cells that
bind to and destroy antigens. Antibodies are specific to
certain antigens
Agglutination
 When antibodies bind to
RBCs, they cause
agglutination, or clumping
Why is this bad?
 Initially, clumps clog small
capillaries, causing pain and
reduced blood flow
 Later, RBCs that are bound to
the antibodies lyse or break
open, releasing hemoglobin
into the blood – which can
cause kidney failure
ABO blood group
 In the ABO blood group, there are two antigens, “A” and “B”,
found on the surface of RBCs
 You can have
one type of
antigen, both
types, or
neither
 You develop
antibodies to
the type of
antigens you
don’t have
during infancy
Rh Blood Group
 The Rh blood group describes ~45 different (but similar) antigens
on RBCs. These antigens are called antigen “D”
 People are Rh + if they have any of the various D antigens. They
are Rh – if the do not have any D antigens.
 Unlike the ABO system, Rh- people must be sensitized to the D
antigen before developing antibodies. That means Rh- people
will NOT have an agglutination reaction the first time they
encounter Rh+ blood … but they will if they have it a second
time.
Blood Type
Our ‘blood type’ is the combination of the antigens from the ABO
and Rh groups – the two groups of antigens that cause the
strongest immune response.
What blood type do you have if you have D antigens only?
O+
If you have A- blood, what type(s) of antigens do you have? What
type(s) of antibodies?
A antigens only; B and maybe D antibodies
Blood type compatibility
The key to transfusions:
You cannot give a person blood that has antigens for
which they have antibodies, otherwise, their immune
system will attack that blood.
Fill out the chart …
Blood Type
A+
AB+
BAB+
ABO+
O-
Can donate to
Can receive from
A+, AB+
A+, A-, O+, O-
A-, A+, AB-, AB+
A-, O-
Which is
the
universal
donor?
B+, AB+
B+, B-, O+, O-
O-
B-, B+, AB-, AB+
B-, O-
AB+
A+/-, B+/-, AB+/-, O+/-
AB-, AB+
A-, B-, AB-, O-
A+, B+, AB+, O+
O+, O-
A+/-, B+/-, AB+/-, O+/-
O-
Which is
the
universal
recipient?
AB+
Blood Type Compatibility &
Pregnancy
 For the most part, blood type compatibility is NOT a
problem during pregnancy because the blood of the baby
and the blood of the mom do not mix.
 However, Rh+ babies carried by Rh- moms can face
serious risks because the
mother’s Rh antibodies can
cross the placenta and attack
the babies blood.
Blood Type Compatibility &
Pregnancy
 There are often no problems affecting the first Rh+ baby carried
by an Rh- mom… why?
Because mom needs to be sensitized by having contact with
Rh+ blood before she will produce Rh antibodies. During labor
and delivery, the baby’s blood and mom’s blood often come into
contact, which sensitizes the mother.
 If the mom becomes pregnant with
a second Rh+ baby, her immune
system will attack the baby’s blood,
causing brain damage or death to
the fetus.
 This can be prevented by giving the
mother medicine that prevents her
from developing antibodies against
Rh antigens.
Blood Typing
Antiserum is a solution that
contains antibodies against a
specific antigen (i.e. antiserum
A contains type A antibodies).
Blood type is determined by
adding antiserum A, B, and D
to blood and observing
whether or not agglutination
occurs.
O+
OA+
AB+
What does an agglutination
reaction with a certain
antiserum mean?
It means that the blood
contains that antigen.
BAB+
AB-
Just for Fun:
Genetics Refresher
We have two versions – or alleles – of every gene. One inherited
from our mom, one from our dad.
The two alleles (genotype) interact to determine our trait
(phenotype) in predictable ways.
 Some alleles are dominant, some are recessive. Dominant
genes show their trait and ‘cover up’ recessive genes.
 IA (A) and IB (B) are dominant to i (O).
 D (+) is dominant to d (–)
 Some alleles are codominant. This means both alleles fully
express their trait.
 IA and IB are codominant with each other.
Genotype to Phenotype
What blood type will result from each genotype?
1.
2.
3.
4.
5.
IAiDD
iidd
IB IB Dd
IA IB dd
IB iDd
Genotype to Phenotype
What blood type will result from each genotype?
1.
2.
3.
4.
5.
IAiDD
iidd
IB IB Dd
IA IB dd
IB iDd
A+
OB+
ABB+
Phenotype to Genotype
What are the possible genotypes for each blood type?
1.
2.
3.
4.
A+
ABOB+
Phenotype to Genotype
What are the possible genotypes for each blood type?
1.
2.
3.
4.
A+
ABOB+
IAIADD, IAiDD, IAIADd, IAiDd
IAIBdd
iidd
IBIBDD, IBiDD, IBIBDd, IBiDd
More important vocab –
Homozygous – both alleles for one gene are the same (e.g. ii)
Heterozygous – the two alleles for one gene are different (e.g. Iai)
Punnett Squares
Punnett Squares are a tool for predicting the traits that will
result from crossing certain genotypes.
Monohybrid Crosses
1. IAi X ii
Note 1: By convention, you
should always write the
dominant allele in front of the
recessive allele for each gene
2. IBIB X IAi
3. Dd X dd
Example #1: IAi X ii
Mom’s eggs
Dad’s sperm
IA
Note 2: A Punnett square isn’t
enough. You must summarize
your answer, like below.
i
i
IA i
ii
i
IA i
ii
Genotypic %
Iai – 50%
ii – 50%
Phenotypic %
A – 50%
O – 50%
Monohybrid Crosses
1. IAi X ii
2. IBIB X IAi
3. Dd X dd
Example #2: IBIB X IAi
Mom’s eggs
Dad’s sperm
IB
IB
IA
IAIB
IAIB
i
IB i
IB i
Genotypic %
IaIB – 50%
IBi – 50%
Phenotypic %
AB – 50%
B – 50%
Monohybrid Crosses
1. IAi X ii
2. IBIB X IAi
3. Dd X dd
Example #3: Dd X dd
Mom’s eggs
Dad’s sperm
D
d
d
Dd
dd
d
Dd
dd
Genotypic %
Dd – 50%
dd – 50%
Phenotypic %
Rh+ 50%
Rh- 50%
Dihybrid Crosses
1.
2.
3.
4.
IAiDd X iiDd
AB- X iiDD
IBiDd X IAiDD
IAidd X IBiDd
Dihybrid Crosses
Example #1: IAiDd X iiDd
IAiDd X iiDd
AB- X iiDD
IBiDd X IAiDD
IAidd X IBiDd
Genotype
IAiDD – 1/8
IAD
iD
Phenotype
A+ 3/8
IAiDd – ¼
Iadd – ¼
A- 1/8
iiDD – 1/8
O+ 3/8
iiDd – ¼
Iidd – 1/8
Mom’s eggs
O- 1/8
Dad’s sperm
1.
2.
3.
4.
IAiDD
IA d
iD
id
IAiDd
iiDD
iiDd
iD
IAiDD
IAiDd
iiDD
iiDd
id
IAiDd
IAidd
iiDd
iidd
IAiDd
IAidd
iiDd
iidd
id
Dihybrid Crosses
Example #2: IAIBdd X iiDD
IAiDd X iiDd
AB- X iiDD
IBiDd X IAiDD
IAidd X IBiDd
Genotype
Mom’s eggs
IAd
Phenotype
IAiDd – 50%
A+ 50%
IBiDd – 50%
B+ 50%
Shortcut!
Dad’s sperm
1.
2.
3.
4.
IA d
I Bd
I Bd
iD
IAiDd
IAiDd
IBiDd
IBiDd
iD
IAiDd
IAiDd
IBiDd
IBiDd
iD
IAiDd
IAiDd
IBiDd
IBiDd
IAiDd
IAiDd
IBiDd
IBiDd
iD
Dihybrid Crosses
Example #3: IBiDd X IAiDD
IAiDd X iiDd
AB- X iiDD
IBiDd X IAiDD
IAidd X IBiDd
Genotype
IAIBDD 1/8
IAIBDd 1/8
IAiDD 1/8
IAiDd 1/8
IBiDD 1/8
IBiDd 1/8
iiDD 1/8
iiDd
1/8
Phenotype
AB+ ¼
A+ ¼
B+ ¼
O+ ¼
Mom’s eggs
IBD
Dad’s sperm
1.
2.
3.
4.
IB d
iD
id
IAD IAIBDD
IAIBDd
IAiDD
IAiDd
IAD IAIBDD
IAIBDd
IAiDD
IAiDd
IBiDD
IBiDd
iiDD
iiDd
iD
iD
IBiDD
IBiDd
iiDD
iiDd
Dihybrid Crosses
Example #4: IAidd X IBiDd
IAiDd X iiDd
AB- X iiDD
IBiDd X IAiDD
IAidd X IBiDd
Genotype
IAIBDd 1/8
IAIBdd 1/8
IAiDd 1/8
IAidd 1/8
IBiDd 1/8
IBidd 1/8
iiDd 1/8
iidd
1/8
Phenotype
AB+ 1/8
AB- 1/8
A+ 1/8
A- 1/8
B+ 1/8
B- 1/8
O+ 1/8
O- 1/8
Mom’s eggs
I Ad
id
id
IBD IAIBDd
IAIBDd
IBiDd
IBiDd
IBd IAIBdd
IAIBdd
IBidd
IBidd
iiDd
iiDd
I Ad
Dad’s sperm
1.
2.
3.
4.
iD
id
IAiDd
IAidd
IAiDd
IAidd
iidd
iidd
Closure
What were our objectives, and what did we learn?
What was our learner profile trait and how did we
demonstrate it?
How does what we did today tie to our unit
question?
Exit Ticket
1. What blood type is shown?
2. What are the possible genotypes of this blood?
3. To which blood types could this person donate
blood?
4. From which blood types could this person
receive blood?
5. What are the genotypic and phenotypic ratios
produced by the cross of IAiDD and IBIBdd?