Genetics Notes
How do we inherit traits?
• Heredity is defined as
the passing of traits
from parent to offspring.
We have_2_ genes for
every trait (one came
from your mom and the
other came from your
dad )
What traits can you inherit?
(Circle the traits that you can inherit.)
Eye color
Height
Ear type
Favorite food
Your cloths
Hair color
Having a tattoo
Favorite music
Can roll tongue
More Traits to consider….
What are genes?
• -Genes are segments of DNA
that carry hereditary
instructions to code for traits.
Genes are located on
chromosomes.
• An allele is different forms of
the same gene.
• Alleles can be dominant or
recessive.
Dominant vs. Recessive
• Dominant trait: The trait observed when at
least one dominant allele for a characteristic
is inherited. Represented by a capitol letter.
• Recessive trait: The trait that is apparent
only when two recessive alleles for the same
characteristic is inherited.
Genotype vs. Phenotype
• The genotype is the genetic make-up of an organism (in
letters). The genotype is the inherited combination of alleles.
• The phenotype is an organisms inherited physical appearance.
Homozygous vs. Heterozygous
• Genotypes can be described as homozygous. Homozygous
is When an organism has two alleles that are the _same.
Another word for homozygous is purebred
Ex: TT ; GG ; dd
• Genotypes can be heterozygous. When an organism has
two alleles that are different. Another word for
heterozygous is hybrid
Ex: Tt ; Gg ; Dd
Important Scientist in Genetics
• Gregor Mendel is
considered the father
of genetics. He used
pea plants to study the
way traits are passed
from one generation to
the next. He was the
first to discover how
some traits are
dominant over others.
Important Scientist in Genetics
• Reginald Punnett developed
a square that is used to
visualize all the possible
combinations of alleles in
offspring resulting from a
genetic cross.