Download Historical Genetics George Mendel Mendel`s Experiment

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Historical Genetics
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George Mendel
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Mendel’s Experiment
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Austrian Monk and Teacher
Experimented with pea plants
No knowledge of genes or chromosomes
Concepts established through math
Click on Image to Play Game
Genetics Vocabulary
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Genes: A heredity factors found on chromosomes
Alleles: Two genes associated with a specific characteristic.
– Each allele is located on a homologous chromosome
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Alleles
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Mendel’s Law of Segregation
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Phenotype: The physical appearance of the gene pair
Genotype: The genetic combinations or make up of the individual trait.
Here’s an Example
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Alleles of a gene occur in pairs and are separated from each other
other during
meiosis and then are recombined during fertilization
Oh no! More Vocabulary!
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Dominant Alleles
– Only need one gene for the characteristic or trait to be expressed.
expressed.
– Represented by a capitol letter
Recessive Alleles
– Must have two genes of the same with the same allele in order for
for the trait to show.
– Represented by a lower case letter
Eye Color
The allele for the phenotype of blue eyes is “b”
The allele for the phenotype of brown eyes is “B”
A Blue eyed in individual can only be “bb” because blue eyes are recessive.
An individual with Brown eyes can Have either “BB” or “Bb” because
because brown eyes are dominant
Are you kidding me, more vocabulary?
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An individual is homozygous or pure for a trait if they have two of the same
allele.
– Ex: blue eyes are “bb”
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An individual is heterozygous for a trait if they have two different alleles for
one trait.
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– Ex: A brown eyed person who is “Bb”
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Test Cross
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To determine what genotype an individual is, a test cross can be done.
– Depending on what offspring come out will give rise to what genotype
genotype the parents could
be
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Pedigree
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Independent Assortment
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Heterozygous individuals show a phenotype intermediate between homologous
homologous parents
“R” = red “r” = white
RR = red
rr = white
Rr=
Rr= pink
Both alleles are dominant and both phenotypes show at the same time.
time.
Multiple Alleles
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Alleles are not completely dominant or recessive.
Co-dominance
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25% would be Homozygous brown
25% would be Homozygous blue
50% would be heterozygous brown
Incomplete Dominance
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To determine what the possible genotypes and phenotypes your kids
kids could have you must
do a punnet square.
Lets cross two heterozygous Brown eyes individuals:
Intermediate Inheritance
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By doing test crosses Mendel found that different traits were inherited
inherited
independently of one another
What color eyes will my kids have?
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A pedigree chart is a chart which tells one all of the known phenotypes and genotypes
genotypes for
an organism and its ancestors
A genetic history
A trait that is based on more than two alleles.
Ex: Blood Type
Sex Linked Traits
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Trait’s in which the gene is only found on the X chromosome
Examples of SexSex-linked Traits:
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RedRed-green colorblindness
Male Pattern Baldness
Hemophilia
Duchenne Muscular Dystrophy
Many of the traits are more common in men because since they have
have only one X
chromosome, even if the allele is recessive it will still show.
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Interaction of Heredity and Environment
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Effect of Light
– With out light most plants only produce a yellow pigment
– In the presence of light, the plant will start to produce chlorophyll,
chlorophyll, turning green and
beginning photosynthesis.
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Effect of Temperature
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Hair color of the Himalayan Rabbits
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Typically white with black extremities
All white in warm climates
Turns black where ice is applied to normally white areas.
Identical Twin Studies
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Twins tend to change phenotypes as they grow older. Believed to happen as being
dependant on the environment.
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