Genetics is a branch of biology that deals with the principles of heredity and variations in all living things
The term Genetics was derived by William Bateson
Greek word gen means to become or to grow into something
Gregor Mendel is an Austrian monk who started the works of the science of genetics
Theory of Pangenesis is proposed by Hippocrates
According to Hippocrates: All organs of the body of a parent gave off invisible seeds, which were like miniaturized building components and were transmitted during sexual intercourse, reassembling themselves in the mother’s womb to form a baby.
Charles Darwin (1868) proposed his pangenesis theory to describe the units of inheritance between parents and offspring and the processes by which those units control development in offspring.
Aristotle emphasized the importance of blood in heredity
Blood supplied generative material for building all parts of the adult body and was the basis for passing on this generative power to the next generation.
The male's semen is a purified blood and woman's menstrual blood is an equivalent of semen
Theory of Preformationism is when the organism is contained in one of the sex cells as a fully developed homunculus (miniature human)
Theory of Inheritance and Acquired Characteristics is based on Pangenesis theory proposed by Jean-Baptiste Lamarck
Theory of Lamarck is a model for evolution wherein he enunciated the law of use and disuse: when some organs become specially developed as a result of some environmental need, then that state of development is hereditary and can be passed on to progeny.
August Weismann first challenged the theory of Pangenesis through Germplasm Theory
Germplasm is sex cells while somatoplasm is cells of all other parts of the body
Mice tail experiment is about cutting off tails of mice generation after generation produced offsprings with normal tail length
Blending theory of inheritance was before Mendel’s time where heredity was thought to be a blending process that offsprings were essentially mixtures of characteristics obtained from both parents.
Kolreuter observed that although hybrids between species might have shown uniform appearance, their fertile offspring would usually produce considerably diversity
Karl Gartner is about plant reproduction
Charles Naudin is a botanist who studied hybridization and heredity
Charles Darwin proposed theory of evolution
Mendel's boyhood experience in grafting trees taught him the importance of attention to detail
Mendel's university experience in physics and natural history taught him to view world as an orderly place and these laws can be stated mathematically
Hybridization is the mating or crossing between two individuals that have different characteristics
Hybrids are the offspring that result from such a mating
1866, Gregor discovered that hereditary characteristics were determined by elementary factors now called Genes.
Gene is inherited and has information regarding structure, function and other biological function and properties
Garden pea is also know as the Pisum Sativum
Two experiments carried by Mendel: Self fertilization and cross fertilization
Self fertilization pollen and egg are derived from the same plant
cross fertilization pollen and egg are derived from different plant
Characters or traits is the morphological characteristics of an organism.
True breeder is a variety that produces the same trait over and over again.
He used an empirical approach and tried to deduce empirical laws.
Monohybrid cross is termed from Mendel crossing two variants that differ in only one trait.
F1 generation showed only one of the two parental traits
F2 generation showed an 3:1 ratio of the two parental traits
Mendel's law of segregation is when during gamete formation, the paired factors segregate randomly so that half of gametes received one factor and half of the gametes received the othr
Alleles are different versions of the same gene
Dihybrid cross is crossing of an individual plants that differ in two traits