Download Heredity not following the Rules

Heredity
not following
the Rules
Incomplete dominance

A heterozygous condition in which both alleles are
partially expressed, often producing an
intermediate or blended phenotype (which is
different than either of the homozygous forms).
Snapdragons
Incomplete dominance
Snapdragons
Incomplete dominance
RR
R’R’
RR’
RR RR’RR’R’R’
Incomplete dominance


Palomino horses are a cross between a
chestnut horse and a cremello (white) color
horse.
Practice the cross using a Punnet Square.
H’
H’
H
HH’
HH’
H
HH’
HH’
Codominance

Codominance –Neither phenotype is dominant.
Instead, the individual expresses both phenotypes.
Co – both are dominant enough to be expressed!!
Dominique chickens
Codominance
BB - Black
WW - White
BW - Black and White
Cross a black
chicken with a
white chicken and
what to you get if
the traits are
CODOMINANT?
W
W
B
BW
BW
B
BW
BW
Predict the
outcome if BOTH
chickens are
dominique
(black and white)
????
Codominance
BB - Black
WW - White
BW - Black and White
B
B
W
BB
BW
W BW WW
BB=1
BW=2
WW=1
Codominance

Another example of codominance is ABO blood
typing. The blood types A and B are codominant
to each other; however, type O is actually
recessive to A and B.
Codominance
BB or BO
OO
AB
AA or AO
When both alleles exist,
both are present!
Codominance
Blood
Group
Antibodies
Can give
blood to…
Can
receive
blood from
AB
None
AB
A, B, AB,
and O
A
B
A and AB
A and O
B
A
B and AB
B and O
O
A and B
A, B, AB,
and O
O
Practicing Blood Types

A man of blood type AA marries a woman
with blood type AB. What is the chance they
will have a child with type AB blood?
A
B
A
AA
AB
A
AA
AB
Practicing Blood Types #2

O?
A man of blood type B marries a woman with
blood type O. What is the chance they will
have a child with type O blood?
O
O
B
BO
BO
B
BO
BO
O
O
B
BO
BO
O
OO
OO
Multiple Alleles

An individual can only have 2 genes thus 2
alleles for a trait, but there could be more
than 2 alleles present in a population. This
type of inheritance is known as multiple
alleles.
Why
Because…
can youyou
onlyonly
have
have
2 2 of
genes
each type
for each
of chromosome!!
trait?
Multiple Alleles - examples


In Blood typing, there are 2 possible alleles
(genes) that could could inherit – A, B, and O,
but you can only inherit 2 of them. In this
case, blood typing is also a trait that has
multiple alleles.
Coat color in rabbits is inherited as a series of
multiple alleles.
Multiple Alleles - examples
Multiple Alleles - examples
What are all of the possible genotypes for a
1. dark-gray coated rabbit? (4)
CC Ccch Cch Cc
2. chinchilla rabbit (3)
cchcch
cchch
cchc
3. Himilayan rabbit(2)
c hc h c hc
4. White rabbit (1)
cc
Multiple Alleles - examples
Predict the phenotype for a rabbit with a cchch.
Chinchilla
Is it possible to obtain a white rabbit if one parent is white and
the other is chinchilla?
Yes. Only if the chichilla is cchc
Polygenic Inheritance

Polygenic inheritance is the inheritance
pattern of a trait that is controlled by two or
more genes. The genes may be on the
same chromosome or on different
chromosomes.


Height in humans
Skin color
Polygenic Inheritance
Gametes
ABC
ABc
AbC
Abc
aBC
aBc
abC
abc
ABC
6
5
5
4
5
4
4
3
ABc
5
4
4
3
4
3
3
2
AbC
5
4
4
3
4
3
3
2
Abc
4
3
3
2
3
2
2
1
aBC
5
4
4
3
4
3
3
2
aBc
4
3
3
2
3
2
2
1
abC
4
3
3
2
3
2
2
1
abc
3
2
2
1
2
1
1
0
Polygenic inheritance in people showing a cross between two mulatto parents (AaBbCc x
AaBbCc). Skin color has now been determined that it is controlled by 3 different genes. The
offspring contain seven different shades of skin color based on the number of capital letters
in each genotype.
POPQUIZ!! (Just kidding)

A roan cow is the product of a red cow and
a white cow. What type of inheritance is
exhibited?
A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic
POPQUIZ!!

Curly headed people have the genotype
HH, while straight headed people have the
genotype hh. A wavy headed person is
heterozygous. What type of inheritance
does this exhibit?
A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic
POPQUIZ!!

How well a person performs on an IQ test is
controlled by multiple genes. Which of the
following types of inheritance does this
exhibit?
A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic
POPQUIZ!!

Hair loss is a trait caused by a gene located
on the X chromosome. This trait would be
considered A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic
POPQUIZ!!

Kim’s has always wondered why her 2nd toe
is longer than her first. She recently
discovered that it is a dominant trait. This
trait is considered to exhibit A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic
BTW
POPQUIZ!!

Here is an easy one! Blood types fall under
the category of which type of inheritance?
A.
B.
C.
D.
E.
F.
Complete dominance
Codominance
Incomplete dominance
Sex-linked
Multiple alleles
Polygenic