Biology 30 – Unit 3 ~Mrs. S. Pipke-Painchaud Genetics Overview
What is Genetics?
- a branch of biology that deals with the heredity of an organism
It is a field in which every year large numbers of significant findings are made. Over the past 5 decades, no five year period has passed without the establishment of 1 or more major research frontiers in genetics.
Genetics is a science, which surrounds us and determines our everyday lives.
Just look at the person next to you ( everyone is unique and different because of their genes)
It is not known when people first recognized the existence of heredity; however, archeologists have discovered evidence (primitive art, preserved bones, skulls and dried seeds), which suggests that animals were domesticated and plants were cultivated thousands of years ago.
Selection of Animals
Between 8000 and 10 000 B.C. horses, camels, oxen and various breeds of dogs (dogs are derived from the wolf family) were domesticated to serve various roles.
The local newspaper said this: “His death deprives the poor of a benefactor, and mankind at large of a man of the nobliest character, one who was a warm friend, a promoter of the natural sciences and an exemplary priest.”
Mendel’s work was not understood or appreciated while he was alive and it wasn’t until the 1900s and even into the 1920s and 30s when people truly understood what he had discovered. (Zephyrus)
conducted experiments with pisum sativum – the garden pea
he wasn’t the first scientist to study the garden pea, but he was one who distinguished himself from others through 1) careful planning and 2) adherence to the scientific method
his work, however, was largely ignored by others until Correns, de Vries, Tschenmak and Bateson all came up with the same ideas.
Mendel Selected the Garden Pea because . . .
it was cheap and readily available as seed in a variety of shapes and colors.
Normally self pollinates
It’s easy to cross pollinate
Takes up little space
Have relatively short generation time (single season)
Produces many offspring (1 pod = 6-10 peas)
Consider the time . . .
Remember that when Mendel was conducting these experiments there was no knowledge of chromosomes or the role and mechanisms of meiosis.
Regardless, Mendel was still able to find distinct units of inheritance existed and then he used this information to predict the behavior of gametes during their formation.
flower color: purple or white
flower position: axil or terminal
stem length: tall or dwarf
pod shape: inflated or constricted
seed shape: round or wrinkled
seed color: yellow or green
pod color: yellow or green
** notice that each unit has a contrasting characteristic
** all strains used were “ true breeding ” peas seeds
offspring looks like the parent i.e. white flowers give rise to white flowers
each trait (characteristic) remains unchanged generation after generation.
** TRAIT : is a characteristic that is heritable from one generation to the next.