http://fi.wikipedia.org/wiki/Gregor_Mendel http://www.personal.psu.edu/staff/d/c/dcw1/graphics/pea_plant.jpg Genetic Inheritance
Father of Modern Genetics • The first person to trace the characteristics of successive generations of a living thing • He was not a world-renowned scientist of his day. • Rather, he was an Augustinian monk who taught natural science to high school students.
Family • Second child of Anton and Rosine Mendel • They were farmers in Brunn • They couldn’t afford for him to attend college • Gregor Mendel then attended the Augustinian Monastery and became a monk
Where Mendel Studied • He was later sent to the University of Vienna to study. By both his professors at University and his colleagues at the monastery, Mendel was inspired to study variance in plants
The Monastery Garden with the greenhouse whichGregor J. Mendel, O.S.A., had built in 1870. Its appearance before 1902.Courtesy of Villanova University Archives. Gregor J. Mendel, O.S.A., experimental garden (35x7 meters) in the grounds of the Augustinian Monastery in Old Brno.Its appearance before 1922. Courtesy of Villanova University Archives.
How Mendel Got Started • Mendel's attraction to research was based on his love of nature. • He was not only interested in plants, but also in meteorology and theories of evolution. • Mendel often wondered how plants obtained atypical characteristics.
The Birth of the idea: Heredity • On a walk around the monastery, he found an atypical variety of an ornamental plant. • He took it and planted it next to the typical variety. • He grew their progeny side by side to see if there would be any approximation of the traits passed on to the next generation. • This experiment was "designed to support or to illustrate Lamarck's views concerning the influence of environment upon plants.“ • He found that the plants' respective offspring retained the essential traits of the parents, and therefore were not influenced by the environment.
Once he crossed peas and mice of different varieties "for the fun of the thing," and the phenomena of dominance and segregation "forced themselves upon notice." He saw that the traits were inherited in certain numerical ratios. He then came up with the idea of dominance and segregation of genes and set out to test it in peas. It took seven years to cross and score the plants to the thousand to prove the laws of inheritance! Mendel's research reflected his personality.
Mendel's work became the foundation for modern genetics. • The impact of genetic theory is no longer questioned in anyone's mind. • Many diseases are known to be inherited • and pedigrees are typically traced to determine the probability of passing along an hereditary disease. • Plants are now designed in laboratories to exhibit desired characteristics. • The practical results of Mendel's research has not only changed the way we perceive the world, but also the way we live in it.
Interesting Facts • Took seven years to prove laws of inheritance • -Basic Laws- • Heredity Factors do not combine • Each member of a parental generation transfers only one half of its heredity factors to each offspring
More Interesting Facts • Mendel’s works became the foundation of modern genetics • Later crossed mice and pea plants • Noticed traits were inherited in certain numerical ratios • Came up with idea of dominance and segregation of genes and set out to test it in peas • Love of nature encouraged his interest in research • Also interested in meteorology and theories of evolution
http://www.fort.usgs.gov/resources/spotlight/prairiedogs/images/people.gifhttp://www.fort.usgs.gov/resources/spotlight/prairiedogs/images/people.gif Why do we look like we do?
Genetics • Is the study of heredity
Heredity: the transmission of traits from one generation to the next http://www.ogdenfinancial.com/images/three%20generations%202.jpg
You have already learned about chromosomes as compact carriers of DNA.
Gene • “A discrete unit of hereditary information consisting of a specific nucleic sequence in DNA (or RNA in some viruses)” • -Campbell Biology
Locus: a gene’s specific location on a chromosome ( the plural is loci)
Homologous Chromosomes: alike chromosomes carrying genes for the same heritable characteristics
Homologous Chromosomes http://library.thinkquest.org/C0118084/Gene/Genetic_variation/dominant_recessive_files/homologous_chromosomes.gif
Allele: an alternate form of a gene • Ie. One coding for blue eyes and one for brown Allele Allele
Centromere • The joining point of 2 sister chromatids
telomere: the protective structure at the end of the chromosome (protects DNA when it is copied)
Sister chromatids • Replicated forms of a chromosome jointed together by the centromere and eventually separated by mitosis or meiosis 2 (Don’t worry we’ll be learning about mitosis and meiosis on Monday)
http://genetics.gsk.com/graphics/chromosome.gif Parts of a Chromosome
Character: a feature that can be inherited by offspring from a parent (i.e. blue eyes) http://sheilasspot.blogspot.com/uploaded_images/Blue%20eyes-750090.jpg
Trait: a variation of a character I.e. blue or green brown eyes are traits http://www.absolutestockphoto.com/albums/userpics/10007/normal_Absolute_7_5469.jpg
What Mendel did • He took true breeding pea plants • Meaning the parents only produced offspring with the same combination of traits that they had. http://mac122.icu.ac.jp/gen-ed/mendel-gifs/02-pea-life-cycle.JPG
The parents possessed a combination of traits below http://www.gwu.edu/~darwin/BiSc150/One/peas.gif
For now we will examine one trait set at a time • This is called monohybridization or a monohybrid cross • The crossing of a single trait
The parents generation is the P generation • The first generation of offspring is the F1generation • The second generation of offspring is the F2generation
The following is adapted from: http://www.borg.com/~lubehawk/mendel.htm#Law%202%20Seg
Mendel's Laws • 1. the Law of Dominance2. the Law of Segregation3. the Law of Independent Assortment
The Law of Dominance • “In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype.”
A dominant trait will mask or cover up a recessive trait • A recessive trait is only seen if the offspring receive a copy of it from each parent
Dominant DOES NOT = better http://www.thefunnypage.com/toes/
A Dominant trait is expressed as a capital letter i.e. A • A Recessive trait is expressed as a lowercase letter i.e. a
The Law of Segregation “During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then"recombined"at fertilization, producing the genotype for the traits of the offspring. “ (more about this on Monday)
The Law of Independent Assortment “Alleles for different traits are distributed to sex cells (& offspring) independently of one another.” In other words the traits can be in any combinations in offspring it doesn't have to be all from the mother or all from the father.
Heterozygous: having 2 different alleles for the same character “Aa”
How do we do this? http://www.fathom.com/feature/122612/mendel.jpg