Download Mendel 2 - Edgartown School

Gregor Mendel (1822-1884)
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Austrian monk
Gardener, scientist,
teacher,
mathematician
A truly brilliant man
Father of genetics
Mendel’s experiments
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Studied pea plants and
followed the traits passed
from one generation to the
next.
Cross-pollinated by hand
literally thousands of plants
over many years.
Closely studied traits such
as seed color, seed shape,
pod shape, pod color,
flower color, etc…
When Mendel crossed various pea plants
he discovered interesting, but predictable
results, over and over again.
What surprised him the most, was how a
trait could “skip” a generation, as if it
disappeared, only to reappear in the next
generation.
Here’s one example (next slide):
Mendel also noticed that certain traits appeared to be
“stronger” than others. He called them dominant. The
weaker trait he called recessive.
Mendel’s conclusions:
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Hereditary traits are passed from parents to their offspring
during sexual reproduction.
For each trait, there are two hereditary “factors” - one from the
mother and one from the father.
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The two inherited factors may be alike (as in purebred), or
different (as in hybrid).
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When they are different, only one will be visible. The visible
factor is called dominant. The hidden factor is called
recessive.
Modern terminology
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Alleles - what Mendel
called “factors”.
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Different forms of a gene.
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One allele from each parent.
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Might be the same from each
parent, or different.
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Genes often occur in pairs of
alleles.
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Homozygous - what is
often called
“purebred” (same
alleles from both
parents).
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Heterozygous - what
is often called “hybrid”
(two unlike alleles from
each parent).
Click on the image to watch a short video (3:15) on
Gregor Mendel.