Lecture 1.2 Laws of inheritance established by Gregor Mendel. 1. An ideal experimental organism characteristics

Plan

1. An ideal experimental organism characteristics

2. The features examined by Gregor Mendel

3. The laws of Gregor Mendel: hybrids uniformity in the first generation (dominance law), the law of segregation, the law of features independent assortment

4. Standard phenotype classes numerical ratios in the segregation and deviations from it

An ideal experimental organism characteristics

For his studies, Mendel chose the garden pea, Pisum sativum, as his experimental organism. This choice proved to be an important one for Mendel. In genetics, an ideal experimental organism has three distinct characteristics.

First, it must have a short generation time and have the capability of producing large numbers of offspring per generation.

The power of Mendel’s work is that he linked mathematical analysis to the study of inheritance. This is possible with observation of large numbers of offspring over multiple generations. Insects and small plants (such as peas) are ideal model organisms.

The second is the existence of easily distinguishable traits. Mendel chose seven traits as “markers”.

Finally, it must be relatively easy to grow and manipulate the ideal organism. Researcher could control breeding (which is relatively easy in plants) and grow large numbers of in a small area.

Few of experimental organisms used by geneticists:

Table Model Experimental Organisms

Species Name Common Name Some Research Uses

Escherichia coli E. coli Bacterial genetics

Drosophila Fruit fly Development, molecular genetics,

melanogaster genome structure, transgenics

Mus muscalis Mouse Mammalian development,

gene regulation

Arabidopsis thalania Wall cress Plant development

Caenorhabditis elegans Roundworm Animal development