Mr. Chapman
Genetics & Gregor Mendel
Biology 30
Genetics & Gregor Mendel
Gregor Mendel

The basic laws of heredity were first formed during the
mid ____________ by an Austrian botanist monk named
Gregor ______________. Because his work laid the
foundation to the study of ____________, Mendel is
referred to as “_____________________________________.”
Mendel’s Pea Plants
Mendel based his laws on his studies of _______________________________.
Mendel was able to observe differences in multiple traits over many
____________________ because pea plants reproduce ______________, and have
many visible traits which include:




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Mr. Chapman
Genetics & Gregor Mendel
Biology 30
Mendel’s Experiments
Mendel noticed that some plants always produced __________________ that had
a form of a trait ______________ like the parent plant. He called these plants
____________ plants. For instance, purebred short plants always produced
___________ offspring and purebred _________ plants always produced tall
offspring.
Mendel crossed purebred plants with _____________ forms of a trait. He called
these plants _______________________, or _____ generation. For instance,
purebred tall plants were crossed with purebred short plants. Mendel observed
that ______ of the offspring grew to be tall plants. None resembled the
Mr. Chapman
Genetics & Gregor Mendel
Biology 30
__________ parent. He called this generation of offspring the _______ __________,
or F1 generation.
Mendel’s Second Experiment
Mendel then crossed two of the offspring tall plants produced from his first
experiment. (Fill in the titles above and below the plants in these notes)
Mendel called this ___________ generation of plants the second ________, F2
generation. To his surprise, Mendel observed that this generation had a ______
of tall and short plants. This occurred even though __________ of the F1
parents were short.
Mr. Chapman
Genetics & Gregor Mendel
Biology 30
Mendel’s Law of Segregation
Mendel’s first law, the ______________________________, has three parts. From his
experiments, Mendel concluded that:
1. ________________________________________________________________________
_____________________________________________________________________________.
2. ________________________________________________________________________
_____________________________________________________________________________.
3. _______________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Mr. Chapman
Genetics & Gregor Mendel
Biology 30
Dominant and Recessive Genes
Mendel went on to reason that one ____________ (gene) in a pair may mask, or
_______, the other factor. Mendel concluded that the _______________ factor
masked the ________________ factor.
Today, scientists refer to the “factors” that control
traits as _________. The different forms of a gene are
called ____________.
Alleles that mask or hide other alleles, such as the
“tall” allele, are said to be _____________.
A _____________ allele, such as the _________ allele, is masked or covered up
whenever the dominant allele is present.
Homozygous Genes
What Mendel referred to as a “purebred” plant we now know means that the
plant has two _________________ genes for a particular trait. For instance, a
purebred tall plant has two tall genes and a purebred short plant has two short
genes. The modern scientific term for “purebred” is ___________________.
According to Mendel’s Law of Segregation, each parent donates one height
gene to the offspring. Since each parent had only short genes to donate, all
Mr. Chapman
Genetics & Gregor Mendel
Biology 30
offspring will also have two short genes (homozygous) and will therefore be
short.
Hybrid Alleles
In Mendel’s ________ experiment, F1 offspring plants received one ______ gene
and one ________ gene from the parent plants. Therefore, all offspring
contained ________ alleles, a short allele and a tall allele. When both alleles for
a trait are present, the plant is said to be a ___________ for that trait. Today,
we call hybrid alleles ______________________. Fill in the above and below pictures.
Although the offspring both have a tall and short allele, only the tall allele is
expressed and is therefore dominant over short.
Mendel observed a variety of _____________ alleles in pea plants other than the
tall allele. For instance, hybrid plants for seed color always have ________ seeds.
Mr. Chapman
Genetics & Gregor Mendel
Biology 30
Law of Independent Assortment
Mendel’s second law, the Law of Independent Assortment, states that each
pair of genes separate __________________ of each other in the production of
________ cells. 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 _______ or ___________ cells. The
plant will donate one ___________ 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 a round seed allele. It will always donate a wrinkled pod
shape. The donation of one allele from each pair is ___________________
of any other pair. For example, if the plant donates the yellow seed
allele it does _______ mean that it will also donate the yellow pod allele.