Introduction to Genetics Chapter 11 Slide 2 The Work of Gregor
Mendel Section 11.1 Slide 3 The Experiments of Mendel Heredity is
the delivery of characteristics from parent to offspring.
Scientific study of heredity is genetics. Austrian monk Gregor
Mendel is the father of genetics. Used pea plants (a model system)
Slide 4 The Experiments of Mendel The Role of Fertilization
Fertilization is when male/female reproductive cells join to make a
new cell. Pea plants normally self pollinate true breeding
Offspring identical Each plant had certain traits. These traits may
vary between individuals. Slide 5 The Experiments of Mendel Mendel
crossed his true breeding plants to see how traits would be
expressed. He studied 7 different traits. Each had two contrasting
characters. Offspring of a cross between different parents are
called hybrids. Slide 6 The Experiments of Mendel Genes and Alleles
Each original pair of plants is the P generation. Offspring are F1
= first filial Genes are the factors (traits) passed from one
generation to the next. Alleles are alternative forms of a gene.
Slide 7 The Experiments of Mendel Dominant and Recessive Alleles
Principle of Dominance (Mendels 2 nd Conclusion) Dominant: trait
will show if one allele present (masks other allele) Recessive:
need two alleles for trait to appear Slide 8 Segregation Mendel
didnt stop with crossing the parent plants. He thought: Where did
the recessive alleles go? He allowed all 7 kinds of plants to self
pollinate. Called these the F2 Slide 9 Segregation The F1 Cross The
F2 plants showed the recessive alleles! of the plants showed this
trait. How could this be? At some point, the recessive allele had
separated from the dominant. Another word for
separation=SEGREGATION Alleles segregate during the formation of
gametes. Slide 10 Segregation During gamete formation, the alleles
for each gene segregate. Each gamete carries only one allele for
each gene.
