1. Mendel’s Legacy
Section 9.1

2. Genetics- the field of biology devoted to understanding how characteristics are transmitted from parents to offspring
Genetics was founded with the work of Gregor Johann Mendel

3. Gregor Johann Mendel Austrian monk who experimented with garden peas
1842- age 21; entered a monastery in Brunn
1851- entered the University of Vienna
Heredity- the transmission of characteristics from parents to offspring

4. Mendel’s garden peas
Mendel observed 7 characteristics of pea plants, each occurring in 2 contrasting traits.
Traits- plant height (long or short stems), flower position along stem (axial or terminal), pod color (green or yellow) pod appearance (inflated or constricted), seed texture (smooth or wrinkled), & flower color (purple or white)

5. Mendel collected seeds from his pea plants
He observed that both purple-flower and white-flower plants grew from the seeds of purple-flower plants

6. He also observed that both tall and short plants grew from seeds obtained from tall plants
Mendel wanted to find an explanation for the variations

7. Mendel’s methods
Mendel documented the traits of each generation’s parents by controlling how much the plants were pollinated
Pollination- occurs when pollen grains produced in the male reproductive parts of the flower (anthers) are transferred to the female reproductive part of the flower (stigma)

8. Self-pollination- occurs when pollen is transferred from the anthers of a flower to either the stigma of the same flower or a flower on the same plant
Cross-pollination- involves flowers of 2 separate plants

9. Self-pollination can be interrupted (and cross-pollination performed) by removing the anthers from a flower and manually transferring the anther to the stigma of another plant
By doing this, Mendel was able to protect his flowers from receiving pollen that might be transferred by wind or insects, giving him more control over the pollination of his pea plants

10. Mendel’s experiments
Plants that are pure for a trait always produce offspring with that trait
strain- denotes plants that are pure for a trait
P1 generation- each parental generation

11. F1 generation- the first filial generation
F2 generation- the second filial generation

12. Mendel’s Crosses & Results
P cross F1 generation F2 generation Actual ratio Probability ratio
Axial X Terminal = Axial axial : :1
207 terminal
Tall X Short = tall tall : :1
277 short
Inflated X inflated inflated : :1
Constricted = cons.
Green X yellow = green green : :1
(pods) yellow
Smooth X smooth ,474 sm : :1
Wrinkled = ,850 wrink.
Yellow X Green = yellow ,022 yellow : :1
(seeds) ,001 green
Purple X White = purple purple : :1
224 white

13. Recessive & Dominant traits
Dominant factor- dominates the other factor of a specific characteristic
Recessive factor- the trait that did not appear in the F1 generation but reappeared in the F2 generation

14. Law of segregation
States that a pair of factors is segregated, or separated, during the formation of gametes.

15. Law of independent assortment
States that factors for different characteristics are distributed to gametes independently.

16. Chromosomes & Genes
Molecular genetics- the study of the structure and function of chromosomes and genes
Allele- each of several alternatives of a gene (Mendel's factors are now called alleles.)