Booklet Project – Genetics Review
• Fold Four blank pages together
• The cover should say Genetics and include a
definition and YOUR NAME
• 1. Mendelian or Simple Dominance
• 2. Incomplete Dominance
• 3. Codominance
• 4. Sex Linked
• 5. Pedigree
• 6. Mendel’s Laws
• 7. Multiple Alleles and Polygenic
Genetics: The scientific study of
heredity
YOUR NAME
Mendelian or Simple Dominance
• Dominant: The gene
• Allele: Different form of
whose trait shows when
a gene
it is present
• True-Breeding: If they
• Recessive: The trait you
self pollinate, they will
do not see unless there
have offspring identical
are two
to themselves (AA or
aa)
• Homozygous: Two
identical alleles
• Hybrid: A cross
between parents with
• Heterozygous: Two
different traits (Aa)
different alleles
Mendelian or Simple Dominance
• Example:
Tall (TT) X Short (Tt)
• Make a punnet square and
tell the genotypes and
phenotypes
• 2 Alleles (T and t)
• 3 Genotypes: TT, Tt and tt
• 2 Phenotypes (Tall / Short)
• Draw a picture
Incomplete Dominance
• Genotype: The genes in
an individual (TT Tt tt)
• Phenotype: How a trait
looks
• Incomplete Dominance:
The heterozygous
phenotype is
somewhere in between
the two homozygous
phenotypes (Blended or
mixture) Neither allele
is completely dominant.
Incomplete Dominance
• Example: Red parent and
White parent: offspring of
red, white and pink
• RR and WW
• Make a punnet square and
tell the genotypes and
phenotypes
• 2 Alleles (R and W)
• 3 Genotypes: RR, WW, RW
• 3 Phenotypes Red, White,
Pink
• Draw a picture
Codominance
• Codominance: Both
alleles contribute to the
phenotype (both are
seen - not blended)
• This is usually described
as solid color parents
with offspring that are
striped or spotted
Co Dominance
• Example: Blood Type
• IA, IB, and i
• Make a punnet square
and tell the genotypes
and phenotypes
• 3 Alleles (IA, IB, and i)
• 6 Genotypes: (IAIA, IAi, IBIB,
IBi, IAIB, ii)
• 4 Phenotypes (types: A, B,
AB and O)
• Draw a picture
Sex Linked Genes
• Sex Linked Genes:
Traits that are inherited
through either the X or
Y chromosome
• Affect males more often
because they cannot
mask an X linked trait
with a dominant allele
Sex Linked Genes
• Example: Color Blindness
• Make a punnet square
and tell the genotypes
and phenotypes
• 2 Alleles (XC, Xc )
• 4 Genotypes: XCXC,XC
Xc,XCY and XcY
• 5 Phenotypes (F No Trait,
F Carrier, Female with
Trait, Male No Trait, and
Male with Trait)
• Draw a picture
Pedigree
• Pedigree: A
chart that
show how a
trait is
inherited in
a family.
• Example:
Simple
Inheritance
Pedigree
• Sex Linked Chart
• Males more often
affected
Mendel’s Laws
• 1. The Law of
Segregation: Each
gamete gets only one
copy of a gene
• 2. Independent
Assortment:
Different traits are
inherited separately
Multiple Alleles
• Multiple alleles means
that more than two
alleles can exist in a
population, however
each individual still only
has two alleles for that
trait
Polygenic Trait
• Some traits are
controlled by more
than one gene
• Examples: Eye color
and skin color
• This explains the wide
variation in eye and
skin color