Download Types of Dominance and Blood Types

Dominance: Co-Dominance,
Incomplete Dominance and Blood
Types
Lesson Objectives
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Minds ON
Yesterday’s Recap
Dominances and Blood Types
Blood Typing Lab
Success Criteria
Homework Take Up
New homework
Minds ON
Two rabbits are heterozygous. Brown fur (B) is
dominant to white fur (b). Dwarf (small) ears
(D) are dominant to floppy ears (d). Draw a
Punnett square showing the possibilities.
We’ll do it together on the board once you’ve
tried it.
Yesterday’s Recap
Dihybrid Crosses
• Refers to the crossing of
two individuals who are
both heterozygous for TWO
traits (e.g. PpTt x PpTt)
• Assumes that these traits
are on different genes and
can occur at the same time.
• E.g. Pod colour
and seed colour
Dihybrid Crosses
• Parent 1 genotype is:
AaBb
• Parent 2 genotype is:
AaBb
Dominances
So far, we have been looking at situations where
a dominant trait completely masks the allele
Bb/BB = dominant
for purple colour
Incomplete Dominance
Occurs when:
- Neither gene is dominant or recessive
- The gene effect is mixed
- We use 2 different letters for the homologous
pair since neither is dominant.
An Example of Incomplete Dominance
With red and white snapdragons, the dominant
allele that codes for the colour red is not
completely dominant over the recessive allele
that produces the white colour. The result is a
pink flower.
Using a Punnett Square
Red Flower – RR
White Flower – WW
x W W
R
R
RW RW
R
RW RW
= 100% Pink Offspring
Co-Dominance
Occurs when:
- Neither gene is dominant or recessive
- Gene effects are NOT mixed
- Therefore, both genes are expressed at the
same time!
- Examples: Roan cow or Camelia flower
An Example of Co-Dominance
Write C (for co-dominance) and a super script
(R=Red, W=white)
• Red haired = CRCR
• White haired = CWCW
• Red and White (Roan) =CRCW
Using a Punnett Square
Red haired = CRCR
White haired = CWCW
Red and White (Roan) =CRCW
X
𝐶
𝑅
𝐶
𝑅
𝐶
𝑊
𝐶𝑊𝐶𝑅
𝐶𝑊𝐶𝑅
𝐶
𝑊
𝐶𝑊𝐶𝑅
𝐶𝑊𝐶𝑅
= 100% Roan
Blood Types – A Special Case
• There are three alleles:
• IA (Type A), IB (Type B) and i (Type O)
– A and B are co-dominant
– O is recessive
• +/- is the Rh (Rhesus) factor (if the Rh blood
antigen is present, the person is Rh+; if not, they
are
Rh-)
Predict offspring bloodtypes for:
Heterozygous type A mother, type O father
Using A Punnett Square
𝐼
X
50% = A
5-% = O
𝐴
i
i
𝐼𝐴i
ii
i
𝐼𝐴i
ii
IA (Type A), IB (Type B) and i (Type O)
-A and B are co-dominant
-O is recessive
Blood Types
AB universal plasma donors
AB+ universal recipients
O+ blood most needed
O- universal RBC donor
Types
Distribution Ratios
O+
1 person in 3
38.4%
O-
1 person in 15
7.7%
A+
1 person in 3
32.3%
A-
1 person in 16
6.5%
B+
1 person in 12
9.4%
B-
1 person in 67
1.7%
AB+
1 person in 29
3.2%
AB-
1 person in
167
0.7%
•
Rhesus
Disease
An individual either has, or does
not have, the "Rhesus factor" on
the surface of their red blood
cells.
• The status is usually indicated by
Rh positive (Rh+ does have the D
antigen) or Rh negative (Rh− does
not have the D antigen) suffix to
the ABO blood type.
• Rhesus Disease occurs when
there is incompatibility between
blood types of mother and fetus.
• Untreated, the result can cause
death of the child.
• Occurs in second and later
pregnancies
Murder Mystery Lab
“I THINK THERE’S BEEN…(sunglasses on)..AN
ACCIDENT!” (with emphasis)
https://www.youtube.com/watch?v=mznsEcZlM
2I&noredirect=1
The Jim Carrey shows us…
https://www.youtube.com/watch?v=HJSqkwyL1
Zo
Lab
There’s been a murder. Hortatio needs your
help! You have to find out who did it.
• Agglutination: refers to the clumping effect of
blood when it is mixed with Anti-A , Anti-B or
Rh serum .
• Go around to each station and sample the
blood to find out the blood type and Rh factor
to determine who killed One-Eyed Earl!