Gregor Mendel

3. Timeline
1822 born July 20 in Heizendorf,
Austria
1833 is enrolled in Piarist secondary
school in Leipnik, Heinzendof
1838 at the age of sixteen begins to
support himself

4. Timeline
1839 becomes ill and was absent
from school for months
1840 enrolls in the University of
Olmutz and studies philosophy
1843 joins the Augustinian
monastery and changes his name
from Johann to Gregor

5. Timeline
1851 Enrolls in the University of Vienna
1856 Begins experiments with genes
(Pea Plant Experiment)
1884 died January 6, in Brno, Austria

8. Who was this Mendel and what the heck is
he doing in a monastery?
• trained himself to be a
naturalist early in life
• joined a monastery in
Brunn, Austria
•Mendel spent his spare time
breeding pea plants.
•He did this over & over & over
again, and noticed patterns to the
inheritance of traits, from one set
of pea plants to the next.
•By carefully analyzing his pea plant
numbers, he discovered three laws
of inheritance.
The dude
was a
total
GENIUS

9. 9
Site of
Gregor
Mendel’s
experimental
garden in the
Czech
Republic

10. Mendel’s first published work:
"Versuche über Pflanzen-Hybriden“
or Experiments in Plant Hybridization
was a landmark in clarity and insight!
Trained as a mathematician
and a biologist, he figured
out the laws of inheritance…
mathematically!!

11. The work of Gregor Mendel
…he called
them his
children!
• worked with pea plants…
Why pea plants???
There was a long-standing tradition of breeding pea
plants at the monastery where Mendel lived and worked

12. So…they were readily available and they come in lots
of varieties!
…there were plants with different flower colors, seed
color, flower position etc..

14. And best of all…
Pea plants flowers can
reproduce by themselves
This allowed Mendel to see if
strains were true breeding and to
produce hybrids

15. How Mendel made hybrids…
He’d then tie little
bags around the
flowers to prevent
contact with stray
pollen.

16. Mendel’s hybridization experiments…
Monohybrid crosses:
Parental
Generation
True-breeding
purple flower x
True-breeding
white flower
F1 generation All purple flowers (the hybrids)
F2 generation
Allowed F1 offspring
to self-fertilize
705 purple
224 white

20. “Brother Mendel! We grow tired of
peas!”

21. The results of Mendel’s monohybrid
crosses led him to propose…
1. All organisms contain two “units of
heredity” for each trait (alleles).
2. Dominant and recessive alleles…
…and organisms can have any combination of
the two alleles (2 dominants, 2 recessives
or a mixture 1 dominant and 1 recessive).
3. The Law of Segregation – during
gamete formation, alleles separate
randomly into separate gametes.

22. 4. Law of Independent Assortment
Mendel’s fourth law, the Law of Independent
Assortment, states that each pair of genes separate
independently of each other in the production of
gametes. For instance, consider an example of the
following gene pairs:
According to Mendels’ Law of Independent Assortment,
the gene pairs will separate during the formation of egg or
sperm cells. The plant will donate one allele from each
pair. The plant will donate either a yellow or green seed
allele, either a yellow or green pod allele, and a wrinkled
or round seed allele. It will always donate a wrinkled pod
shape. The donation of one allele from each pair is
independent of any other pair. For example, if the plant
donates the yellow seed allele it does not mean that it will
also donate the yellow pod allele.

23. A bit of genetic terms …
phenotype vs. genotype
What the
organism
looks like
What alleles
the organism
has - its
genetic makeup

24. More terms …
homozygous vs. heterozygous
2 of the
same alleles:
PP or pp
2 different
alleles:
Pp
P
p

25. 25
Failure of Mendel’s Laws
Incomplete Dominance
F1 hybrids have an appearance somewhat
in between the phenotypes of the two
parental varieties.
Example: snapdragons (flower)
red (RR) x white (rr)
RR = red flower
rr = white flower
R
R
r r
copyright cmassengale

26. 26
Incomplete Dominance
Rr
Rr
Rr
Rr
R
R
r
All Rr = pink
(heterozygous pink)
produces the
F1 generation
r
copyright cmassengale

27. 27
Incomplete Dominance
copyright cmassengale

28. SOURCES/REFERENCES
Blumberg, Robert. Mendel Web. 24 Oct. 2002. http://mendelweb.org
http://www.carolina.com/achievements/janapr/mendel.asp
"Villanova University - Gregor Mendel." Villanova University Astronomy &
Astrophysics. Web. 22 Sept. 2011. http://astro4.ast.vill.edu/mendel/gregor.htm.
"Exploring Nature Educational Resource." Exploring Nature Educational
Resource: A Natural Science Resource for Students and Educators. Web. 21
Sept. 2011. http://www.exploringnature.org/db/detail.php?dbID=22
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