Genetics
LESSON 1
INTRODUCTION TO GENETICS
The Work of Gregor Mendel
•Every living thing - plant or animal,
microbe, or human being - has a set of
characteristics inherited from its
parents.
•Since the beginning of recorded
history, people have wanted to
understand how that inheritance is
passed from generation to generation.
Genetics – the scientific study of heredity
and variation.
Gregor Mendel
•Austrian Monk
•Born 1822 in the Czech Republic
•Worked at a monastery and taught
high school.
•Tended the monastery garden.
•Grew peas and became interested in
the traits that were expressed in
different generations of peas.
True breeding
•If allowed to self-pollinate they would
produce offspring identical to
themselves
•He was also able to crossbreed peas
for different traits.
Genes and Dominance
•Mendel studied seven different pea
plant traits.
•Each trait he studied had a contrasting
form.
•The offspring of crosses between
parents with different traits are called
Hybrids.
•When Mendel crossed plants with
different traits, he expected them to
blend, but that's not what happened at
all.
•All of the offspring had the character of
only one of the parents.
Mendel drew two conclusions:
1. Inheritance is determined by
factors that are passed from
generation to generation - today
we call these factors genes.
2. The Principal of Dominance
•Some alleles are dominant, and
some are recessive.
Alleles – different forms of genes
Dominant – cover up the recessive from
Ex: T = tall
Recessive – gets covered up with the
presence of a dominant allele.
Ex: t = short
Segregation
•Mendel wanted to answer another
question.
Q: Had the recessive alleles disappeared?
Or where present in the F1 plants?
•To answer this he allowed the F, plants
to produce an F 1 generation by self-
pollination.
