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For thousands of years
farmers have selectively bred
animals to get the traits they
want.
Farmers mate one animal
with qualities they want with
another with qualities they
want hoping to get animals
with both qualities.
Case Study:
In 1917 the average farmer wanted cows
that would produce both milk and beef.
Short horn (Durham) cows were popular
with the farmers because they had large
calves to sell for beef and gave a
reasonable amount of milk. The condensed
milk factories that bought the farmers’
milk wanted the farmers to keep Holsteins
because they produced large quantities of
milk. When the milk factories demanded
Holstein cows, rather than buy a whole
new herd, many farmers got together and
purchased a Holstein bull and introduced
the breed into their herds. The result was a
cow that gave more milk, but still had a
large, if not quite so beefy, calf.
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Gregor Mendel – 1822
Mendel was an Austrian (not Australian) monk.
He notice 2 black horses that had a tan foal and
wondered how that could happen? (no she wasn’t cheating )
At the monastery he worked in the garden.


It was here that he noticed pea plants had 6 different
characteristics (traits).*see next slide
He observed some traits disappeared and then
reappeared in later generations.
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Baby step through punnet squares
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http://users.adelphia.net/~lubehawk/BioHELP!/psquare.htm
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Why peas?

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Grow Quickly
Many different
varieties.
Self-pollinating
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Studying on trait at
time. Mendel used only
purebreds for each trait.
(TT, tt)
Mendel’s 1st experiment:

Round vs Wrinkled
 He mated a RR X rr.
 What happened?
 The offspring are called
first generation (F1) and
they were all Round.
What happened to
the wrinkled trait?

What happened to the
wrinkled Mendel then
crossed two offspring from
the F1 generation.
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
Ss X Ss
In the second generation F2,
the wrinkled trait shows up
again.
Mendel repeated this for the
other traits he studied and
saw the same phenomenon.
Your eyes are green but his are grey
and mine are brown
All caused by genes……
Now you try it……..
•Cross a Homozygous Red parent with
Homozygous blue parent. What are the
offspring's:
Genotype:
•Genotype
100% AA
•Phenotype
__________
Phenotype:
100% RED
•Cross to Heterzygous Parents.
•What are the offsprings…
•Genotype
•Phenotype
Genotype
AA: Aa: aa
1 : 2 : 1
Phenotype
Red : Blue
3 : 1
•
•
•
We each have
genes
Found on
every
chromosome
They code for
traits
•
You have two genes
per trait,
• ONE from mom
• ONE from dad
They’re called
ALLELES!!
homozygous
Two of the same
alleles is called,
homozygous
(YY /Yy)
Or….
Two different
alleles is called,
heterozygous
(Yy)
heterozygous
It’s genetics,
It’s genetics:
How traits are passed on
Phenotype 
expression of
genes, what you
look like…
These are your
traits:
-
Color –eyes / hair
Shape- body / face
Genotype  the
genes that control
characteristics
Are On…..
chromosomes
Dominance 
expressing one
trait over another.
Recessive is masked
but expressed only
when both alleles
are recessive.
Autosomes 
1st -22ndpair
chromosome, do
not determine
gender,
Sex Chromosomes
23rd pair –
determines sex
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Complete Dominance
Incomplete Dominance
Codominant
Blood Type
COMPLETE DOMIANCE
-Only Dominant & Recessive
-Only 2 Phenotypes
CODOMIANCE
-Both Alleles expressed equally.
-Third phenotype = speckled
BB- Black
Bb- Black
bb- White
INCOMPLETE DOMIANCE
-Both Alleles blend together
-Third Phenotype = new color
BB- Black
Bb- Speckled
bb- White
BB- Black
Bb- Gray
bb- White
Animation created by Molly in Ulead Gif Animator
www.promotega.org/.../inheritance_patterns.htm
Blood Types
- Multiple Alleles and Codominance
•In humans, there are four blood types (phenotypes): A, B, AB, and O.
•Blood type is controlled by three alleles. A, B, O.
•O is recessive, OO alleles must be present for the person to have type O.
•A & B are codominant.
•If you have an A allele and a B allele, their blood type is type AB
•Crosses involving blood type often use an I to denote the alleles - see chart.
How do they study genes?
Uses in everyday life?


Doctors take amniotic fluid from the unborn
child. (amniocentesis)
Scientist then take one cell, break it open and
extract the DNA. The picture looks like this…
Then they match up
the homologous
chromosomes to create
the following picture
x x
Male

Female
What is the difference???
Clearer view

Determining Genotypes
 Test Cross
 Pedigrees


Used to determine genotype of organism.
How to testcross:


Cross an individual of unknown genotype with an
individual with a known genotype.
For example: A Red Flower …is it RR or Rr?


Testcross with a known (homozygous recessive) to
determine genotype.
Geno-typically what would this look like?
rr
_RR_ X ___

Do the Cross…(click to see cross)
rr
_ Rr__ X ___
aa
_AA_ X ___

Phenotype:

100% Red
*No matter always yields
Dominant trait.
Aa x aa

Phenotype:
50 % White
 50% Red
* Recessive white appears.

http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial4_files/fig_14_6.gif
PUREBRED

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Keeps blood lines pure.
Selective Breeding –
breeder chooses trait
which is passed on.
Harmful traits appear.
Examples


Blue People
Czar of Russia
HYBRID




A mixing of genes.
Natural Breeding –
nature determines
which trait is passed on.
Dominant Trait appear
thus making stronger
healthier individuals.
Examples


Blake
Lab
Used to determine Genotypes
Shows patterns of inheritance.
Uses symbols to represent
members of a family.
Male
Male
Female Unaffected
Female Affected
Blue People of Kentucky
Click Picture to see Pedigree
The filled in symbol represent
individuals who express the trait.
Pedigree of the Fugate Family
The Story of Hemophilia
Late in the summer of 1818, a human sperm and egg united to form a human
zygote. One of those gametes, we don't know which, was carrying a newly
mutated gene. A single point mutation in a nucleotide sequence coding for a
particular amino acid in a protein essential for blood clotting. The zygote
became Queen Victoria of England and the new mutation was for
hemophilia, bleeder's disease, carried on the X chromosome.
A century later, after passing through three generations, that mutation may
have contributed to the overthrow of the Tsar and the emergence of
communism in Russia. Victoria passed the gene on to some of her children
and grandchildren, including Princess Alexandra, who married Nicholas II,
Tsar of Russia, in 1894. By 1903, the couple had produced four daughters.
The next year, the long awaited male heir appeared - His Imperial Highness
Alexis Nicolaievich, Sovereign Heir Tsarevich, Grand Duke of Russia. From
his father, the baby Alexis inherited the undisputed claim to the throne of all
the Russias. From his mother, he inherited an X chromosome carrying a copy
of the mutant gene for hemophilia. Soon after his birth, signs of Alexis'
mutant gene appeared. At six weeks, he experienced a bout of uncontrolled
bleeding and by early 1905 the royal physicians had concluded that he was
suffering from hemophilia.
•Inbreeding: creating
purebreds
•Marrying close relatives, as often occurred in royal families did increase the
chances that recessive harmful alleles (like hemophilia) would be inherited.
•Impacts of Inbreeding:
•Inbreeding has caused many breeds of dogs to have harmful genetic traits.
•Dalmations are often deaf, and other dog breeds have high frequencies of
epilepsy, blindness, and hip displaysia.
BLAKE
What
race
is
Blake?
First bred in the 1970’s by Wally
Conron , the Labradoodle is a very
lovable dog, known for their
exceptional intelligence and
trainability, low to non-shedding
coat, low allergy coat, and lack of
doggie odor. One of the finest
family pet around! A Labradoodle
is a crossbred or hybrid dog created
by crossing the Labrador Retriever
and the Standard or Miniature
Poodle.
Initially bred for hunting with
guns, quick running, swimming,
and fighting...and their sense of
smell is hardly to be credited."