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Fundamentals of Genetics
Gregor Mendel
• Mendel was an
Austrian monk who
studied genetics by
using pea plants.
• Mid 1800’s
Gregor Mendel
• Mendel observed
different
characteristics of the
plants (called traits).
Gregor Mendel
• When he planted the
offspring seeds of
purple flowered
plants, he noticed that
the flowers were
purple and white.
• This lead to the
question of “WHY?”.
Gregor Mendel
• A pure trait is one that always produces
offspring with that trait.
Generations
• Parental Generation =
P1
• Cross pollination of
the P1 generation
results in the F1
generation. F = Filial
• Cross pollination of
the F1 generation
results in the F2
generation.
Recessive vs. Dominant Traits
• Dominant = a trait
that hides the
presence of another
trait for the same
characteristic.
• Recessive = a trait
that is hidden by the
presence of another
trait.
Attached =
Recessive
Free =
Dominant
The Law of Segregation
• A pair of factors is
separated during the
formation of gametes.
The Law of Independent
Assortment
• The factors for
different
characteristics are
distributed to gametes
independently.
It’s in your Genes
• A gene is a segment
of DNA on a
chromosome that
controls a particular
hereditary trait.
It’s in your Genes
• Alleles are the
alternative forms of a
gene.
Geno. Vs. Pheno.
• Genotype is the
genetic makeup of an
organism.
• It is often written with
letters such as TT, Tt,
or tt.
Geno. Vs. Pheno.
• Phenotype is the
external appearance
of an organism.
• Such as Tall, Short,
Green, Yellow
Hetero. Vs. Homo.
• “Homo” means the
same
• “Hetero” means
different
• Homozygous
dominant : TT
• Heterozygous: Tt
• Homozygous
recessive: tt
Probability
• The likelihood that a
specific event will
occur.
• It is expressed as a
decimal, percent or
fraction.
Probability
• Formula
# of times an event is expected to happen
# of opportunities for an event to happen
Punnett Squares
• Used to predict
probability in various
crosses.
Monohybrid Cross
• Involves only one pair
of contrasting traits.
Dihybrid Cross
• Involves two pairs of contrasting traits.