Transcript 26 Incomplete and Codominance Notes

Genetics Continued . . .
Incomplete Dominance
and
Codominance
Essential Question: How can more complex
traits be inherited and expressed in ways other
than complete dominance?
Incomplete Dominance
• Incomplete dominance occurs when one
trait is not fully dominant over the other
trait.
What would a heterozygous individual look
like in this case?
• The heterozygous phenotype is a mixture of
both phenotypes.
Codominance
• Codominance occurs when one trait is not
fully dominant over the other trait.
What would a heterozygous individual look
like in this case?
• In the heterozygous situation, BOTH traits
are expressed at the same time.
• Because neither allele is dominant or
recessive, both alleles are written as capital
letters, but using two different letters.
Blood Types
Blood Types
• There are three alleles in blood types and
these alleles are codominant.
• Alleles:
A, B, O
• Blood types:
A, B, AB, O
• Blood type alleles determine the proteins on
the membrane of the blood cells.
Antigens – the proteins on the surface of the
blood cell
• A person has antibodies to fight off any
proteins that their blood does not contain.
• Blood types are determined by mixing blood
samples with antibodies for each blood type.
If the blood agglutinates (clumps), then that
blood type is present.
• Example: Type A antibody is mixed with the
blood and it agglutinates, what blood type(s)
could it be?
• A or AB
Rh Factor
Rh is another protein on the surface of blood
cells. It is controlled by a separate gene.
Rh is written as either + or –
• You can donate blood to someone with the
same proteins or more proteins.
• You can receive blood with the same proteins
or fewer proteins.
Blood Type Facts
http://chapters.redcross.org/br/northernohio/I
NFO/bloodtype.html
CSI: Tucson
Date: January 16, 2013
Time: 9:48pm
Location: Tucson Mall parking lot
Event Description: A witness called police and reported
seeing a fight in a Tucson Mall parking lot. The witness
gave vague details because it was dark outside and the
lights in the parking lot were broken. The witness claims to
have seen two men in a violent fight or struggle in the
parking lot. Both men appeared to be injured and the fight
ended with one man falling to the ground and the other
man taking something from him and running away. At this
time, the witness reportedly ran away so as not to be seen
by either assailant.
When police reported to the scene, they
did not find any victim, witness, or
assailant. The only evidence found at the
scene was blood on the asphalt. From
further investigation, police came up with
two possible suspects for the assailants in
the fight. The parents of both suspects are
willing to give blood samples to prove the
innocence of their sons. Testing will be done
to determine the blood types of the blood
found at the scene and of the parents.
Test Results:
Two blood types were found at the scene.
Blood Sample #1:
Agglutination with both anti-A antiserum and anti-B
antiserum
Blood Sample #2:
Agglutination with anti-A antiserum only
Parents of Suspect 1: Mother: heterozygous B
Father: Type O
Parents of Suspect 2: Mother: AB
Father: Homozygous A
Question:
Which suspect was involved in the crime?
Conclusion: Answer the question using
complete sentences. Back up your
answer by telling what blood types were
found at the scene and explain how you
are able to determine which suspect the
blood belongs to.