1. Gregor Mendel ~ Father of Genetics
Mini Biography Video

2. Gregor Mendel Discovered the basic principles of heredity
Worked with pea plants
Studied 7 different traits

3. Mendel’s Peas
Self-pollination - using sperm & egg of the SAME plant
Results in offspring IDENTICAL to the parent
Cross-pollination – using sperm & egg from two DIFFERENT plants
Results in offspring with traits from BOTH parents

4. Mendel’s Observations
Crossed pure breeding yellow (yy) pod plants with pure breeding and green (YY) pod plants
To his surprise, ALL the offspring had green (Yy) pods!!!

5. Mendel’s Observations
Crossed heterozygous green (Yy) with heterozygous green (Yy).
Result= 3 green pods : 1 yellow pod

6. How did the yellow pod reappear??
Say
WhaT??

7. One allele is dominant over the other.
Mendel’s Conclusions
Two conclusions:
Individuals carry two alleles for each trait, but pass down only one allele to offspring
One allele is dominant over the other.

8. Mendel’s Conclusions
When present, dominant alleles will always be expressed
Recessive alleles will only be expressed if there are 2 present
EX: Tall dominant over short
EX: Yellow seeds dominant over green seeds

9. Segregation of Alleles During Meiosis
Reappearance of recessive allele showed that the parent’s alleles must separate allowing only them to pass on only one allele.
Each gamete carries one allele for each gene
Ex. Either tall or short

10. Segregation of Alleles During Meiosis
Each gamete carries one allele for each gene

11. Cornell Summary