GENETICS INTRO

• 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