blood types. co-dominance when two or more alleles for a gene contribute to the phenotype
Post on 29-Dec-2015
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Blood Types
Co-dominance
• When two or more alleles for a gene contribute to the phenotype
Blood type alleles
• IA = type A marker (antigen)
• IB = type B marker (antigen)
• IO or just I = No markers (antigen)
• Antigen – means marker on the surface of a cell
**antigens are how your body can identify which cells belong to you and which are foreign**
Antigens vs. Antibodies
• Antigens are how your body recognizes which cells are yours and which cells are foreign.
• Antibodies are what your body produces to fight off any cell that is not “marked” as yours.
THINK – PAIR - SHARE
• If there are 3 co-dominant alleles, how many different blood types (phenotypes) are possible?
• 4 possible blood types– A– B– AB– O
Type A bloodgenotypes = IAIA or IAIO
AAA
A
A
Has only A antigens on the surface
Has Anti-B antibodies
Type B bloodgenotypes = IBIO or IBIB
Has only B antigens on the surface
Has Anti-A antibodiesB
B
B
B
B
Type AB bloodgenotype = IAIB
A
A
A
AB
B
B
B
Has A and B antigens on the surface
No antibodies!
Type O bloodgenotype = IO IO
Has NO antigens on the surface
Makes Anti-A and Anti-B antibodies
Rh Blood Group
• Rh positive indicates presence of antigen D
• Rh negative indicates absence of Antigen D
• Rh antigens, like A and B antigens are inherited and present from birth
• Anti-D antibodies are not produced until after an individual is sensitized to antigen D
Fig. 14.21
What blood can I receive?Blood type: Can receive from: Can give to:
Type A A or O A or AB
Type B B or O B or AB
Type AB A, B, AB or O*UNIVERSAL RECIPIENT
AB only
Type O O only A, B and AB*UNIVERSAL DONOR
What happens if the wrong blood
type is given?
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