Blood typing and genetics February 18 2020 Blood

Blood typing and genetics February 18, 2020

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 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 Can donate to A+, AB+ A+ A-, A+, AB-, AB+, AB+ B+ BB-, B+, AB-, AB+ AB+ AB-, AB+ ABA+, B+, AB+, O+ O+ A+/-, B+/-, AB+/-, O+/O- Can receive from A+, A-, O+, O- Which is the universal donor? A-, OB+, B-, O+, O- O- B-, O- Which is the universal recipient? A+/-, B+/-, AB+/-, O+/A-, B-, AB-, OO+, OO- 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. IAi. DD iidd IB IB Dd IA IB dd IB i. Dd

Genotype to Phenotype What blood type will result from each genotype? 1. 2. 3. 4. 5. IAi. DD iidd IB IB Dd IA IB dd IB i. Dd 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, IAi. DD, IAIADd, IAi. Dd IAIBdd iidd IBIBDD, IBi. DD, IBIBDd, IBi. Dd 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 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 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 he t rite , w n, allele o i nt B e v e on of th nt c By ront rese : 3 in f e p e r t No llele oth a A a en b wh Mom’s eggs Dad’s sperm IB IB IA IAIB i Genotypic % Ia. IB – 50% IBi – 50% Phenotypic % AB – 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 Genotypic % Dd – 50% dd – 50% Phenotypic % Rh+ 50% Rh- 50%

Dihybrid Crosses 1. 2. 3. 4. IAi. Dd X ii. Dd AB- X ii. DD IBi. Dd X IAi. DD IAidd X IBi. Dd

Dihybrid Crosses Example #1: IAi. Dd X ii. Dd AB- X ii. DD IBi. Dd X IAi. DD IAidd X IBi. Dd Genotype IAi. DD – 1/8 IAD i. D Phenotype A+ 3/8 IAi. Dd – ¼ Iadd – ¼ A- 1/8 ii. DD – 1/8 O+ 3/8 ii. Dd – ¼ Iidd – 1/8 Mom’s eggs O- 1/8 Dad’s sperm 1. 2. 3. 4. IAi. DD IAd i. D id IAi. Dd ii. DD ii. Dd i. D IAi. Dd ii. DD ii. Dd id IAi. Dd IAidd ii. Dd iidd id

Dihybrid Crosses Example #2: IAIBdd X ii. DD IAi. Dd X ii. Dd AB- X ii. DD IBi. Dd X IAi. DD IAidd X IBi. Dd Genotype Mom’s eggs IAd Phenotype IAi. Dd – 50% A+ 50% IBi. Dd – 50% B+ 50% Shortcut! Dad’s sperm 1. 2. 3. 4. IAd IBd i. D IAi. Dd IBi. Dd i. D

Dihybrid Crosses Example #3: IBi. Dd X IAi. DD IAi. Dd X ii. Dd AB- X ii. DD IBi. Dd X IAi. DD IAidd X IBi. Dd Genotype IAIBDD 1/8 IAIBDd 1/8 IAi. DD 1/8 IAi. Dd 1/8 IBi. DD 1/8 IBi. Dd 1/8 ii. DD 1/8 ii. Dd 1/8 Phenotype AB+ ¼ A+ ¼ B+ ¼ O+ ¼ Mom’s eggs IBD Dad’s sperm 1. 2. 3. 4. IBd i. D id IAD IAIBDD IAIBDd IAi. DD IAi. Dd IBi. DD IBi. Dd ii. DD ii. Dd i. D IBi. DD IBi. Dd ii. DD ii. Dd

Dihybrid Crosses Example #4: IAidd X IBi. Dd IAi. Dd X ii. Dd AB- X ii. DD IBi. Dd X IAi. DD IAidd X IBi. Dd Genotype IAIBDd 1/8 IAIBdd 1/8 IAi. Dd 1/8 IAidd 1/8 IBi. Dd 1/8 IBidd 1/8 ii. Dd 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 IAd id id IBD IAIBDd IBi. Dd IBd IAIBdd IBidd ii. Dd IAd Dad’s sperm 1. 2. 3. 4. i. D id IAi. Dd IAidd 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 IAi. DD and IBIBdd?