1. Introduction to Genetics
Chapter 11
Introduction to Genetics

2. Genetics = study of heredity
Gregor Mendel – Austrian monk, mid-late 1800s
“Father of Genetics”
Studied pea plants

3. Good b/c:
*** Self-pollinate
* Grow quickly
* Many offspring
*** Show 1 of 2 possible outcomes for traits
* Easy to grow
* Short life span

4. Mendel’s Experiments
Step 1 – Let plants self-pollinate, so they produce identical offspring => pure-bred plants = Parental Generation (P)
Ex. Tall plants produce tall offspring

5. Step 2 – took 2 different types of P generation plants & crossed them (mated)
- offspring = First filial generation (F1)
Ex. Tall X short -> all tall offspring

6. Step 3 – allowed F1 gen. to self-pollinate
- offspring = Second filial generation (F2)
- offspring was mostly tall, some short
- Calculated totals -> average ratio 3:1 in F2

8. Mendel’s Conclusions Parents transmit info = “factors” (now genes)
Everyone has 2 factors (1 from mom, 1 from dad)
Factors – homozygous – same type of factor
heterozygous – different form of factor

9. 3) Alternate form of a factor = allele
ex. If tall, allele = T; if short, allele = t
Genotype = genetic makeup Ex. Tt
Phenotype = physical appearance Ex. tall

10. 4) Alleles segregate randomly during meiosis
5) Dominant alleles = control, seen
recessive alleles = hidden

11. Mendel’s Laws LAW OF SEGREGATION
= each pair of alleles segregates during gamete formation (meiosis)
LAW OF INDEPENDENT ASSORTMENT
= gene pairs segregate into gametes randomly and independently of each other

12. LAW OF DOMINANCE
= One allele is shown, one is hidden