1. Chapter 3 Genetics: The Science of Heredity
trait
heredity
genetics
purebred
gene
allele
dominant allele
recessive allele
hybrid
Section 1: Mendel’s Work

2. Studied math and science Priest, taught high school
Gregor Mendel
1851, University of Vienna
Studied math and science
Priest, taught high school
Took care of garden
Grew hundreds of pea plants
Noticed traits

4. Trait: physical characteristics
Heredity: the passing of traits from parents to
offspring
A. Mendel’s Peas
Have many traits that exist in only
two forms
2. Mendel was able to cross-pollinate peas

9. B. Mendel’s Experiments
Cross pollinated plants with opposite
forms of a trait
2. purebred: always produces offspring with
the same form of a trait as the parent
3. Crossed purebred tall plants with purebred
short plants

12. C. Other Traits
1. Mendel studied six other traits:
-seed shape
-seed color
-seed coat color
-pod shape
-pod color
-flower position
2. Results were all the same:
-only one form of the trait appeared in F1
-in F2 ¼ of plants had the “lost” trait

15. D. Dominant and Recessive Alleles
Mendel reasoned that individual factors
control the inheritance of traits in peas
2. genes: factors that control traits
3. alleles: different forms of a gene
4. Some alleles are dominant, while other alleles
are recessive

16. E. Understanding Mendel’s Crosses
1. Hybrids: have two different alleles for the trait