Gregor Mendel (1822-1884)

-the tendency for traits to be passed from parent to offspring

-first person to systematically study heredity -Austrian monk who studied science & math -worked w/garden peas in his monastery

7, each of which had 2 distinguishable/contrasting traits -He let each variety self-feritlize for many generations to ensure it was true-breeding (homozygous)

Crossed individuals from 2 diff varieties that differ only in one trait -P (parental) generation: pure bred lines -F1 (first filial) generation: offspring of cross-fert. -F2 (second filial) generation: offspring of self-fert. of F1 plants

Let each variety self-fert for several gen's, producing a true-breeding P gen

To produce an F1 gen, Mendell pushed aside the petals of a white flower and cut off the anthers -then he placed that pollen onto the female structures of a similary castrated purple flower, where cross-fert took place

To produce an F2 gen, let the plants in the F1 gen self-fert

For all 7 contrasting triats studied, observed the same results: -1. The F1 gen showed only one of the 2 parental traits -he called it the dominant trait -the recessive trait was not expressed -2. The F2 gen showed a 3:1 ratio of the dominant: recessive parental traits

The 3:1 ratio is a disguised 1:2:1 ratio

Purple flowers x white flowers yellow seeds x green seeds round seeds x wrinkled seeds green pods x yellow pods inflated pods x constricted pods axial flowers x terminal flowers tall plants x short plants

One maternal and one paternal -these alleles, present on chromo, are distributed to gametes during meiosis

A grid structure that enables the calc of the results of simple genetic crosses -possible gametes are listed along 2 opp sides -genotypes of potential offspring are represnted by the cells in the square -Thefrequency of these genotypes in the offspring is expressed by a probability

-Mendel's procedure- determine ind's genetic composition -A purp-flowered plant can be homo (PP) or heter (Pp) (genotype) -one cannot tell by looking at the phenotype (physical apperance) -one can tell from results of a cross between the test plant & a homo recessive plant

(Mendel) - one of th most imp theories in the hist of science -been so well reported, considered "laws"

The 2 alleles of a gene separate when forming gametes, and gametes combine randomly in forming offspring