2. Gregor Mendel
Austrian monk born 1822
Lived in a monastery
and taught high school
Experimented with pea plants by cross
breeding plants with different
characteristics and studying results.
Known as the father of Genetics
3. Mendel’s Principles
Law of Inheritance – Characteristics or
traits are inherited by individual units
known as “genes”.
4. Vocabulary
Gene – the sequence of DNA that codes
for a protein and thus determines a trait.
Example – a gene
will determine plant
height in peas.
5. Mendel’s Principles
Law of Segregation - states that during
the formation of reproductive cells
(gametes), pairs of hereditary factors
(genes) for a specific trait separate so
that offspring receive one factor from
each parent.
6. Vocabulary
Allele – one of a number of different
forms of a gene.
Example:
this flower
carries an
allele for white
and an allele for purple flowers
7. Mendel’s Principles
Law of Independent
Assortment - states
that chance deter-
mines which factor
for a particular trait
is inherited.
8. Mendel’s Principles
Law of Dominance – states that when 2
or more forms of a gene exist (alleles),
some forms are dominant and others are
recessive
9. Dominant/Recessive
Shapes for Pea seeds
R = round (Dominant)
r = wrinkled (recessive)
Genotype Phenotype
RR Round homozygous dominant
Rr Round heterozygous dominant
rr wrinkled homozygous recessive
13. Monohybrid Crosses
Practice some monohybrid crosses
BB x BB
BB x Bb
BB x bb
Bb x Bb
Bb x bb
What are the genotypic ratios?
What are the phenotypic ratios?
