Genetics, Part 1: Genes



_*** Genetics- Part 1- Genes **

** Mendel **



Mendel was an Austrian monk who taught natural science and worked on plant
breeding experiments.

He developed a basic understanding of genetics and inheritance.


** Mendel’s Work **



It took him 2 years to select the pea plant as his subject.

He collected data for 10 years.

His sample sizes were large; he tabulated results from 28,000 pea plants.

He replicated his experiments.

He analyzed his data with statistics (probability theory).


** Characteristics of Garden Peas: **



Peas are easy to grow, and take little space. 

They are inexpensive.

They have a short generation time compared to large animals so that a large
number of offspring can be obtained in a short amount of time.

They have some distinct characteristics that are easy to recognize.  These
characteristics can be used when trying to determine patterns of

They are easily self-fertilized or cross fertilized.



** Traits Studied by Mendel **



smooth or wrinkled seeds

yellow or green seeds

red or white flowers

inflated or constricted pods

green or yellow pods

axial or terminal flowers

tall or dwarf plants



** Mendels Crosses **



Mendel used pure-breeding individuals in the first (P[1]) generation.



*    yellow X green




*        all yellow



F[2   ]

* 3/4 yellow, 1/4 green_*

** Mendel’s Results for 7 different crosses **





*F[2] ratio*

smooth X wrinkled seeds all smooth

5474 smooth
1850 wrinkled 2.96:1

yellow X green seeds all yellow

6022 yellow
2001 green 3.01:1

axial X terminal flowers all axial

651 axial
207 terminal 3.14:1

red X


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