1. Review: Types of Reproduction
Sexual reproduction: two organisms produce a new unique organism = VARIABLITY!!!
Asexual reproduction: one organism produces a new nearly identical organism = no variability!

2. Genetics
The branch of biology that is concerned with the ways in which hereditary information is transmitted from parents to offspring.

3. How does it work? Women carry XX sex chromosomes
Men carry XY sex chromosomes (technically, men determine the sex of a baby)
Many diseases/conditions are carried on the X chromosome (nothing is carried on the Y)
** ColorBlindness
** Hemophilia
Women can be healthy ‘carriers’
Men either have or don’t have the disease.

4. Mendel’s 1st experiments
Trait = specific characteristic that varies from one individual to another
Height (tall or short)
Seed color (green or yellow)
Seed texture (smooth or wrinkled)
Mendel crossed plants with contrasting traits
P (Parental) = original pair of plants
F1 (First Filial) = first set of offspring
(filius means “son” in Latin)
Hybrids = offspring of parents crossed with different traits (aka HETEROzygous)

5. Mendel’s 1st conclusions
Biological inheritance is determined by factors passed from one generation to the next = genes
Each gene occurred in two contrasting forms that produced different characteristics = alleles

6. The Principle of Dominance
Some alleles are dominant and others are recessive

7. Mendel’s 2nd experiments
Mendel crossed the F1 hybrid plants
F1 (First Filial) = first set of offspring (hybrids)
F2 (Second Filial) = offspring of self-pollinated F1
Dominant vs. Recessive alleles
Upper case letter = dominant allele
Lower case letter = recessive allele

8. Mendel’s 2nd conclusions
The dominant allele masked the corresponding recessive allele in the F1 generation
The reappearance in the F2 generation indicated that the alleles separated during gamete (sex cell) formation
Each gamete contains a single copy of each gene
The recessive alleles can be paired up again in the F2 generation

9. The Principle of Segregation
Alleles are separated (segregated) during gamete (sex cell) formation (meiosis)

10. Concept Map Gregor Mendel Pea plants “Factors” determine traits Law of
Section 11-3
Gregor
Mendel
experimented with
concluded that
Pea
plants
“Factors”
determine
traits
Some alleles
are dominant,
and some alleles
are recessive
Alleles are
separated during
gamete formation
which is called the
which is called the
Law of
Dominance
Segregation
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