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How peas helped explain heredity

Gregor Mendel (1822–1884) is often called the father of genetics

because of the breakthroughs he made in the study of heredity, or

biological inheritance. From 1856 on, Mendel cultivated peas in the

garden at the monastery where he lived and worked. He found it quite

interesting that these plants could have such varied properties. He

noticed that there are pea plants with white or red ﬂowers, and ones

with yellow or green peas. But Mendel didn’t stop there, at the mere

observation. He started to cross-breed the peas systematically. For

example, he tried consistently combining the pollen of red-blooming

plants with the ova (egg cells) of white-blooming plants.

Then, Mendel took on an enormous task: He investigated the

features of well over 10,000 offspring plants — whether they had red,

white, or maybe even blue blossoms. Gradually, Mendel was able to

show that the instructions for features such as ﬂower color are

individually inherited from the egg and sperm cells (which, in a plant,

are the pollen grains) of the mother and father plants. He showed that

sometimes both the features from the mother and father plants

showed up in the offspring plants. But sometimes, only one of the two

features expressed itself.

He was ultimately able to summarize everything in three famous

laws of inheritance. This was the beginning of modern genetics, even

if words such as gene and genetics were totally unknown to him. He

recognized that living organisms such as plants and animals carried

many individual programs for characteristics such as ﬂower color and

passed them on to their offspring. He eventually ﬁgured out that each

pea plant has two copies of the program for any one feature, such as

ﬂower color.

Heredity:

Investigating Traits

12 | Heredity: Investigating Traits

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