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BIOLOGY CHAPTER 11. INTRODUCTION TO GENETICSPG 262. 11-1 THE WORK OF GREGOR MENDEL. Gregor Johann Mendel- (born 22nd July 1822, died 6th January 1884). Introduction:"EARLY IDEAS ABOUT HEREDITY" .
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11-1 THE WORK OF GREGOR MENDEL Gregor Johann Mendel- (born 22nd July 1822, died 6th January 1884)
Until the 19th century people believed that heredity was a BLENDING inheritance and the nature of these factors was unknown…
*The resemblance of children was explained by the THEORY OF BLENDING INHERITANCE.
GENETICS- the branch of biology that studies heredity….the scientific study of heredity.
HEREDITY- the passing of traits from parents to their young...biological inheritance.
Heredity is the reason we have different species....cats have kittens, dogs have puppies, oak trees produce acorns...
NO THIS CANNOT HAPPEN! NO! This CANNOT Happen!
Gregor Mendel , an Austrian monk born in 1822, is known as the "father of genetics".
At the age of 21 Mendel entered a monastery in "Brno"and in 1851 was sent to the Univeristy of Vienna to study science and math.
He spent 2 years at the University and then returned to the monastery and spent the next 14 years teaching at the monastery.
Mendel was a teacher & was also responsible for tending the garden at the monastery. From this responsibility came the foundation of genetics.
Mendel studied the garden pea plants and conducted experiments that unlocked some of the secrets of heredity.
Teacher Tube Video Clip • http://www.teachertube.com/v.php?viewkey=2cbe4813cae2f7715336
Mendel found that pea plants have both male and female parts and that normally, pollen from the male part of a pea flower fertilizes the female egg cells of the same pea flower.
TRUE BREEDING- when allowed to self pollinate, the parents produce offspring identical to the parent plant.
SELF POLLINATION- the process in which pollen falls from the male part of a flower to the female part of a flower of the same plant.
PUREBRED- belonging to a group of organisms that can produce offspring having only one form of a trait in each generation.
*Mendel used pea plants that had been allowed to self pollinate for several generations because they were purebred.
The purebred pea plants would produce offspring that were identical to themselves.
Tall plants produced only tall offspring. Short plants produced only short offspring. Plants that had green seeds produced offspring with green seeds.
Mendel’s pea plants produced seeds by self pollination. These true breeding plants were the basis for Mendel's experiments.
The seeds that were produced inherited all of their characteristics from the single plant that "created" them.
Mendel prevented self-pollination in some plants and fertilized the eggs of a flower with the pollen from a different plant.
CROSS POLLINATION- the transfer of pollen from the flower of one plant to the flower of another plant...fertilization of a plant's eggs by the pollen of another plant.
Cross pollination produces seeds that are the offspring of 2 different plants.
Through cross pollination Mendel was able to cross plants with different characteristics.
Mendel studied a few isolated traits...ones that were easily observed.He studied 7 traits...See figure 11-3 page 264
TRAIT- a specific characteristic that a living thing can pass on to its young
Traits Medel Studied: Seed Shape, Seed Color, Seed Coat Color, Pod Shape, Pod Color, Flower Position, Plant Height.
Studying only a few traits made measuring the effects of heredity much easier.
Mendel crossed pea plants with different characteristics for the same trait....tall with short.
Flower positions: axial and terminal...axial along the sides...terminal at the end.
HYBRID- an organism that results from crossing parents with differing traits or characteristics…
Mendel thought that he would get half short and half tall plants when he crossed a short and tall plant…
