Transcript Genetics

Genetics
Genetics and Mendel!
Mendel (b. 1822) in Czech Republic,
moved to Vienna, Austria
 Worked as a monk and a HS teacher,
gardened in spare time….
 Little did he know his work would be
the foundation of modern genetics
 Genetics: the scientific study of
heredity—the core of biology!
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Vocabulary
Fertilization: The process were male
and female GAMETES unite.
 True breeding: Self-fertilization, it
occurs when male gamete within a
flower combines with a female gamete
in the same flower.
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Cross pollination: Pollen from one
flower fertilizes a second different
flower.
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Trait: A specific CHARACTERISTIC
that varies for one INDIVIDUAL to
another.
Generations
F1= First Filial (offspring), F2= Second Filial
Vocabulary
Hybrid: The offspring of crosses
between parents with different TRAITS.
 Genes: A sequence of DNA that codes
for a protein and thus determines a
trait.
 Alleles: Different forms of a TRAIT.
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Mendel’s Conclusions
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Biological inheritance is determined by
TRAITS that are passed from one generation
to the next.
Today we call Mendel’s factors:
Traits=Genes, Form= Allele
Every trait is controlled by one GENE that
occurs in 2 contrasting forms called ALLELES.
Principle of Dominance
Some alleles are DOMINANT and some
are RECESSIVE
 An organism with a dominant allele for
a trait will ALWAYS exhibit that form of
the trait.
 An organism with a recessive allele for
a trait will exhibit that form only if the
dominant allele is NOT present.
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Segregation
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Medel’s question, “Did the recessive
alleles disappear?”
Principle of Segregation
 Segregation
= Separation
 The separation of alleles occurs
during the process of MEIOSIS
when gametes are formed. Each
gamete carries a single copy of
each gene.
Vocabulary
Homozygous: two identical alleles (TT) or
(tt)
 Heterozygous: two different alleles (Tt)
 Phenotype: physical or outward
appearance (ex: tall, short, yellow, green)
 Genotype: genetic makeup (TT, Tt, Gg,
gg)
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In Short…
Capital Letters (T) = Dominant Trait
 Lowercase Letters (t) = Recessive Trait
 T= Tall and t= short
 Homozygous: Having 2 IDENTICAL
alleles for a trait. (TT) or (tt)
 Heterozygous: Having 2
DIFFERENT alleles for a trait. (Tt)
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Prediction Uses Probability,
not magic!
Probability- likelihood a particular
event will occur
 We can study Mendel’s crosses with
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Punnett Squares (diagram that shows
gene combinations from a genetic
cross)
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Used to predict and compare the
genetic variations that can occur
How Punnett Squares Work