Transcript The Father of Genetics

Who started it
all?
What is Genetics?

Genetics is the study of biological
inheritance patterns and variation in
organisms
Mendel Background

 Gregor Mendel was an
Austrian Monk, born that
worked and lived
throughout the 1800s.
 He was a physics teacher
with a passion for plants,
which he explored in the
garden of his monastery.
 Mendel worked with Pea
Plants to establish the
basic principles of
genetics
 He proved that traits are
inherited as discreet units
from parents and given to
their offspring
 He described how traits
are passed between
generations
What did
Mendel
Do?
What got Mendel
Started?

He observed that some tall plants produce tall offspring,
while other tall plants produce short offspring. He also
noticed that some plants with yellow seeds produce
offspring with yellow seeds while others produce white
seeds.
(The event he observed is called inheritance)
How did he begin?
Mendel made three key choices when
choosing to work with pea plants
• Controlled breeding
• Use of Purebred Plants
• Use of “either/or” traits
Mendel examined 7 specific traits in pea
plants:
1. Seed Shape
2. Seed Color
3. Flower Color
4. Flower Position
5. Pod Color
6. Pod Shape
7. Plant Height
Mendel worked with pea plants because
they self-pollinate
The Experiment

P (Parental) Generation
Mendel crossed (mated) purebred pea plants that either had round or
wrinkled peas. The result was the F1 generation
F1 (First Filial) Generation
The F1 generation of peas were all round. There were no wrinkled offspring
even though one of the parents had only wrinkled peas. Mendel decided to
cross two offspring from the F1 generation. The result was the F2 generation
F2 (Second Filial) Generation
The cross result in the F2 generation was that 75% of the peas were round and
25% of the peas were wrinkled.
The Results
Mendel concluded that
even though the wrinkled
trait physically disappeared
in the F1 generation, that it
had not truly disappeared.
The wrinkled trait had been
masked by the round trait.
That is why the wrinkled
trait reappeared in the F2
generation. He also noted
that the traits reappeared in
a 3:1 ratio
(3 round: 1wrinkled)
His First Conclusion

1. The Principle of Dominance and Recessiveness
 Each characteristic of a plant was controlled by some
“factor”. The factors of different plants interacted when
the plants reproduced. Depending on the factors
involved, one may “mask” another. For example, when
a plant with green pods is crossed with a plant who has
yellow pods, the green pods appear in the offspring and
yellow pods do not.
 We can say that the round pea characteristic is dominant
and the wrinkled pea characteristic is recessive.
His Second Conclusion

Principle of Segregation
Mendel said that the two factors for a
characteristic separate during the formation
of the egg and the sperm. Each egg cell and
each sperm cell only gets ½ of the
information. If they did not separate, then
the new organism would have too many
chromosomes.
His Third Conclusion

The Principle of Independent Assortment
Mendel noticed that when he crossed plants
with two different characteristics, in the
offspring of these plants, the traits did not
necessarily travel together. For example, if
you crossed a Tall Green seeded plant with
a Short Yellow Seeded plant, both your tall
and short plants can have Green seeds.