When the hybrid offspring shows an intermediate phenotype between the two parents. Example: Flower...
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Transcript of When the hybrid offspring shows an intermediate phenotype between the two parents. Example: Flower...
When the hybrid offspring shows an intermediate phenotype between the two parents.
Example: Flower color
CRCR = red CWCW= white CRCW = pink
High Cholesterol-
LL= normal CholesterolLL’= High CholesterolL’L’ = Very High Cholesterol
https://www.youtube.com/watch?v=fHpMT7xJR3s
See Cholesterol Worksheet for info and Punnett Squares.
When the hybrid offspring shows both parental traits.
Example: Roan Coat Color in horses
RR = redR’R’ = whiteRR’ = roan (has both red and
white hairs).
• An inherited disease where people who have the allele for sickle cell have defective hemoglobin, causing misshaped blood cells that do not carry enough oxygen . • In the heterozygous form, the disease causes
anemia and pain, but also provides a tolerance to malaria.
• https://www.youtube.com/watch?v=R4-c3hUhhyc
• In the homozygous form, the disease can cause organ failure and death.
Sickle Cell Anemia (codominance in humans)
• The change in shape occurs in the body’s narrow capillaries after the hemoglobin delivers oxygen to the cells.
Sickle-cell anemia
Normal red blood cell
Sickle cell
Sickle-cell anemia
• Abnormally shaped blood cells, slow blood flow, block small vessels, and result in tissue damage and pain.
Normal red blood cell
Sickle cell
AA= normal
AS= mild anemia- some sickle cells, some normal- resist malaria infection
SS= disease, anemia, organ damage
https://www.youtube.com/watch?v=Zsbhvl2nVNE
What is the probability that a baby will have full blown sickle cell disease if both parents have mild sickle cell anemia?
NN = normalNS = mild anemiaSS = full anemia
A S
A AA AS
S AS SS
25% chance of SS
• Mendel’s laws of heredity also can be applied to traits that have more than two alleles.
Multiple Alleles Govern Blood Type
• The ABO blood group is a classic example of a single gene that has multiple alleles in humans.
Multiple Alleles Govern Blood Type
Human Blood Types
lA lA or lAlilB lB or lBilA lB
ii
Genotypes Surface Molecules Phenotypes
AB
A and BNone
ABABO
• The gene for blood type, gene l, codes for a molecule that attaches to a membrane protein found on the surface of red blood cells.
The ABO Blood Group
• The lA and lB alleles each code for a different molecule.
• Your immune system recognizes the red blood cells as belonging to you. If cells with a different surface molecule enter your body, your immune system will attack them.
• The lA allele is dominant to i, so inheriting either the lAi alleles or the lA lA alleles from both parents will give you type A blood.
Phenotype A: Blood type A
• Surface molecule A is produced.
Surface molecule A
• The lB allele is also dominant to i.
Phenotype B: Blood type B
• To have type B blood, you must inherit the lB allele from one parent and either another lB allele or the i allele from the other.
• Surface molecule B is produced.
Surface molecule B
• The lA and lB alleles are codominant.
Phenotype AB: Blood type AB
• This means that if you inherit the lA allele from one parent and the lB allele from the other, your red blood cells will produce both surface molecules and you will have type AB blood.
Surface molecule B
Surface molecule A
• The i allele is recessive and produces no surface molecules.
Phenotype O: Blood type O
• Therefore, if you are homozygous ii, your blood cells have no surface molecules and you have blood type O.
• Determining blood type is necessary before a person can receive a blood transfusion because the red blood cells of incompatible blood types could clump together, causing death.
The importance of blood typing
Blood type A
Blood cells have
surface protein A
Blood type B
Blood cells have
surface protein B
Blood type AB
Blood cells have
surface proteins
A and B
Blood type O
Blood cells have
no surface
proteins