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Mendelian Genetics
KEY VOCABULARY
 Dominant: inherited characteristic that
appears in an organism- usually
represented with capital letter.
 Recessive: inherited characteristics
often masked by the dominant
characteristic and not seen in an
organism- usually represented with
lowercase letter.
Dominant vs. Recessive
Dominant- Widow’s Peak
(W)
Recessive- No Widow’s
Peak (w)
Vocabulary
Phenotype
Genotype
 physical traits that appear
in an individual as a result
of its genetic make-up
 Genetic Make Up of an
individual
– Ex:
 Purple flower vs. White
flower
– Ex:
 P= purple; p= white
 PP
Vocabulary
 Allele: different forms of the
gene for a trait (2 for each trait)
For Example:
Both have
hair color
information
 # 4 from Mom
# 4 from Dad
For Example:
But Mom’s
could say
“blonde”
While Dad’s
says “brown”
Vocabulary
–Homozygous: having two
identical alleles (PP or pp)
–Heterozygous: having two
different alleles for a trait (Pp)
Mendel’s Experiments
Three Principles
Principle of Dominance
 one trait is masked or covered
up by another trait
Principle of Segregation
the two factors (alleles) for a
trait separate during gamete
formation
Principle of Independent Assortment
 factors of a trait separate
independently of one another
during gamete formation;
–EX: whether a flower is purple has
nothing to do with the length of the
plants stems - each trait is
independently inherited