Transcript Nonmendelian Inheritance File

PATTERNS OF HEREDITY
NON-MENDELIAN?
• Hint look for the number of phenotypes
• If there are more than 2 phenotypes
per trait then it can not be Mendelian.
CODOMINANCE
• Third Phenotype – both appear
R
R
• RR = Red
• WW = White
• RW = Red White
• Genotypic Ratio ________
• Phenotypic Ratio _______
W
RW
RW
W
RW
RW
CODOMINANCE
The meaning of the prefix “co-” is “together”.
In codominance, the heterozygous allows both
dominant traits to appear together in the
phenotype of organisms.
Red X White --> Red & White spotted
INCOMPLETE DOMINANCE
• Third Phenotype – blending
R
R
• RR = Red
• R’R’ = White
• R R’ = PINK
• Genotypic Ratio ________
• Phenotypic Ratio _______
R’
RR’
RR’
R’
RR’
RR’
INCOMPLETE DOMINANCE
Produces offspring with a third phenotype
that is a blending of the parental traits.
RED Flower X White flower
PINK
It is like mixing paints, red + white will make
pink.
+
KEY TERMS
Multiple alleles - traits controlled by
more than two alleles.
Autosomes - in humans, the 22 pairs of
matching homologous chromosomes.
Sex chromosomes - the two
chromosomes that determine the sex of
an individual. XX = Female, XY = Male
MULTIPLE ALLELES
If there are 4 or more possible phenotypes for
a particular trait, then more than 2 alleles for
that trait must exist in the population’s gene
pool. We call this multiple alleles.
There may be multiple alleles within the
population, but an individual can have only
two of those alleles. WHY?
ANSWER
Because individuals have only two
biological parents. We inherit half of
our genes form ma and the other half
from pa, so we end up with two alleles
for every trait in our phenotype.
MULTIPLE ALLELES
•
IA
IB
Blood Types
• IAIA and IAio = A
• IBIB and Ibio = B
• IAIB = AB
io
IAio
I Bi o
io
IAio
IBio
• ioio = O
Genotypic: 2IAio:2IBio
Phenotypic: 2A:2B
SEX-LINKED TRAITS
In 1910, Thomas Hunt Morgan
discovered traits linked to sex
chromosomes in fruit flies.
Sex-linked traits are controlled by genes
located on sex chromosomes.
SEX-LINKED TRAITS
• Cross a white-eyed male with a heterozygous red-eyed female.
Xr
Y
X
XR
XRXr
XRY
Xr
XrXr
XrY
Genotypic: 1XRXr:1XrXr:1XRY:1XrY
Phenotypic: 1Female Red:1Female white:
1 Male Red: 1 Male white
POLYGENIC INHERITANCE
Polygenic inheritance is controlled by two
or more genes. This type of inheritance
occurs when many genes interact to produce
a single trait. (Upper and lower case letters
are used to represent the alleles.) Examples:
skin color and height in humans.
TESTCROSS
1. The organism with the dominant trait is always
crossed with an organism with the recessive trait.
2. If ANY offspring show the recessive trait, the
unknown genotype is heterozygous.
3. If all the offspring have the dominant trait, the
unknown genotype is Homo. Dom (?)
4. Large numbers of offspring are needed for
reliable results.
MORE KEY TERMS
Carrier - a heterozygous organism that
contains the recessive trait.
Pedigree - a graphic representation of an
individual’s family tree.
HELPFUL WEBSITES
• http://anthro.palomar.edu/mendel/mendel_3.htm
• http://prezi.com/v3ndrbgvgadl/non-mendelian-inheritance/
• http://biology.clc.uc.edu/courses/bio105/geneprob.htm
• http://www.biologycorner.com/lesson-plans/genetics/
SAMPLE STORY PROBLEM 1
• The famous Botanist Professor Ingendera was able to
produce a new species of purple Antheridionus flower.
Which he promptly named Antheridionus purplinium. He
had crossed a red Antheridionus redlinium from the far
northern region of Crendor with a blue Antheridionus
bluinium from the southern region of Brelizon. How is this
possible? Show a Punnett Square with its possible
genotypic and phenotypic ratios.
ANSWER STORY PROBLEM 1
• He crossed a Red with a Blue flower.
R’
R’R’ = Red
R’R = Purple
RR = Blue
Genotypic: 4R’R
R’
R
R’R
R’R
R
R’R
R’R
Phenotypic: 4 Purple
SAMPLE STORY PROBLEM 2A
Terry read the sign at the side of the road again,
“Purebreed Wumples For Sale - Cheap!” The man
only wanted $200. He mentioned something about
needing the money for his wife’s operation. Terry
remembered that purple fur is recessive and golden
fur is dominant in Wumples. The man’s Wumples
do have golden fur. Terry also knew that Purebreed
Wumples usually go for $500 - this deal seemed to
good to be true.
SAMPLE STORY PROBLEM 2B
Terry had just been paid for doing yard-work for all of
his neighbors all summer and he had exactly $200. Terry
decided to buy a Wumple from the man at the side of the
road. He thought if nothing else I can breed Wumples
and sell the Wumplets and make a profit.
What kind of cross should Terry do in order to determine
if his newly acquired Wumple is homozygous dominant
or heterozygous? Show the possible Punnett Square
cross and the possible genotypic and phenotypic ratios.
ANSWER STORY PROBLEM 2
• Testcross - If any of the offspring turn out to have the recessive trait, then he knows
that his Wumple is heterozygous.
T
T_ = Gold
tt = purple
Genotypic: 2Tt:2tt
t
t
Tt
tt
t
Tt
tt
Phenotypic: 2Gold:2purple
SAMPLE STORY PROBLEM 3A
• Timmy buys a new Gronk. He thinks that it is a
very special Gronk, because it has both blue and
purple stars on each feather. He remembered
seeing a blue Gronk at his Grandfather’s house
in the far eastern city of Tangeria. His Gramp’s
Gronk has only blue stars. Timmy snickered as
he thought to himself how much better his Gronk
had to be than Gramps.
SAMPLE STORY PROBLEM 3B
• Timmy also remembered seeing a purple-starred
Gronk in a zoo during a class field trip - the one
where Paul got sick all over the Giant Zork’s
glass cage. How is it possible that Timmy’s
Gronk has both blue and purple stars? Show a
Punnett Square that can explain this.
ANSWER STORY PROBLEM 3
• Codominance - cross a Blue starred with Purple starred.
B
BB = Blue stars
B
BP = Blue & Purple stars
PP = Purple stars
P
BP
BP
P
BP
BP
Genotypic: 4BP
Phenotypic: 4 Blue Purple starred