Historical Background of Genetics PDF

HISTORICAL BACKGROUND OF GENETICS Prepared by: BIOSCI 5 INSTRUCTORS Genetics heredity and variation Grk. Word “gen” – to become or to grow into something study of heredity, or how an organism’s characteristics are transmitted from parent to offspring.  A. Classical Geneti...

HISTORICAL BACKGROUND OF GENETICS Prepared by: BIOSCI 5 INSTRUCTORS Genetics heredity and variation Grk. Word “gen” – to become or to grow into something study of heredity, or how an organism’s characteristics are transmitted from parent to offspring.  A. Classical Genetics: Techniques and methodologies used in genetics are called classical genetics. Areas in 1. Behavioral: The study of the influence of varying Genetics genetics on animal behavior. (Genetics is 2. Clinical: field of genetics to diagnose and treat and divided into counsel of genetic disorders. 2 main 3. Molecular: It focuses on the structure of genes. areas) 4. Population and Ecological: Subfields of classical genetics. 5. Genomics: Knowledge of large-scale of genetic patterns. 6. Genetic Engineering: Manipulation of genes. Areas in B. Mendelian Genetics: It governs the transfer of heredity Genetics characters from parent to offspring. (Genetics is This is based of Gregor Mendel’s work divided into published in 1865-66. 2 main This work was rediscovered by Thomas areas) Hunt Morgan in 1900. He integrated the chromosome theory of inheritance i.e core of classical genetics.  1. Genetics as the basis of Biological sciences: Provide a foundation for biological studies. Laws of inheritance help us to understand the principles of embryology, population, taxonomy, evolution, and ecology. 2. Role of genetics in food production: Rules of genetics help to introduce new varieties of plants and livestock. Scope/ 3. Disease control: Gene therapy helps to cure many genetics- based diseases. Applications 4. Conservation of Wildlife: Conservation of wildlife can be of Genetics achieved in one way by conserving the germplasm of endangered species. Genetics 5. Genetic Engineering/Biotechnology: Genetic Engineering has many applications, including: a. Development of transgenic crops b. Gene Therapy c. Improvement in Food production d. Control of Genetic Diseases e. Gene mapping  6. Behavioral Genetics: It studies the influence of varying genetics on animal behavior. 7. Clinical Genetics: There are several genetic disorders that physicians are trained to diagnose and treat. Scope/ 8. Molecular Genetics: It focuses on the structure Applications and function of a gene. of Genetics 9. Population and Ecological Genetics: Population and ecological genetics are closely Genetics related subfields of genetics. Population genetics is the study of distribution and change in alleles. 10. Genomics: It allows the study of large-scale genetic patterns i.e genomic sequence  Gregor Johann Mendel (1822-1884) ▪ Austrian monk ▪ “Father of Genetics”. The Gregor Mendel, while experimenting on pea Beginnings of plants, discovered the way in which traits are Genetics passed from one generation to the next. Laws of Mendel “Law of independent assortment” “law of segregation”  In 1866, he discovered that hereditary characteristics were determined by genes: 1. The gene is inherited from generation to generation Two 2. The gene provides information regarding important the structure and function, and other attributes of biological properties of the characteristic the gene are: or trait it controls. Before Mendel’s time Heredity was thought to be a “blending” process  There are two basic types of cell: eukaryotic and prokaryotic A gene is the fundamental unit of heredity Genes come in multiple forms called alleles Important a gene for coat color in cats may exist in Basic alleles that encode either black or orange fur. Concepts Genes encode phenotypes Genetic information is carried in DNA and RNA Where are genes located? Chromosomes  How does chromosomes separate? through the processes of mitosis and meiosis Genetic information is transferred from Important DNA to RNA to protein Basic Mutations are permanent, heritable Concepts changes in genetic information Some traits are affected by multiple factors Evolution is genetic change  1859 Origin of Species by C. Darwin 1865 Experiment on Plant Hybridization by G. Mendel 1903 Chromosomes Discovered 1906 Term Genetics Coined by W. Bateson 1913 Genetic map by Alfred Sturtevant Timeline of 1918 R.A Fisher shows correlation traits with factors (genes) Notable 1927 Physical changes in chromosomes named as “mutation” Discoveries 1928 Griffith Experiment on bacteria 19th Century 1931 Crossing over was explained by Barbara McClintock 1869 Friedrich Miescher successfully isolated the “nuclein” inside the nuclei of human white blood cells. Not long after, he was able to prove that the “nuclein” is present in other cells as well. 1871 Ernst Haeckel proved that the genetic material is in the nucleus.  1902: Walter Sutton and Boveri postulated the Chromosomal theory which describes that chromosomes carry the cell’s genetic material (gene). 1905: Nettie Stevens observed the sex chromosomes X and Y. Timeline of 1905: Thomas Morgan discovered the sex-linked inheritance of the white eye traits in fruit flies (Drosophila melanogaster) Notable 1905: William Bateson: coined the term “genetics” from the Greek Discoveries word “genno” which means to “give birth” in order to describe the study of inheritance and variation. (20th 1909: Bateson published his book entitled Mendel’s Principles of Century) Heredity. 1910: Reginald Punnett and Bateson discovered the science of genetic linkage. They also coined the term “epistasis” to describe the interaction between two traits. 1944: The experiments of Oswald Avery and his colleagues proved that DNA is the molecule responsible for inheritance.  1941 Tatum and Beadle show that genes are responsible for protein synthesis 1944 Avery, McLeod, and McCarty isolate DNA 1950 Chargaff Rule A=T and C=G Transposons Timeline of (Jumping Genes) discovered by Barbara McClintock Notable 1952 Hershey-Chase experiment prove phages Discoveries contain DNA as their genetic information (20th 1953 DNA is a double helical structure proved Century) by two young scientists, Watson and Crick 1956 Humans have 46 Chromosomes, proved by Jo Hin Tjio Albert Leaven 1958 DNA is a semiconservative model proved by Measelson-Stahl  1961 Genetic code arranged in triplet (Nirenberg and P. Leder) 1964 Howard Temim proves Watson central dogma is not always true. 1970 Restriction enzyme discovered (Werner Timeline of Arber) Notable 1977 DNA sequence was determined by F. Sanger Discoveries 1983 Karry B. Mullis discover PCR 1985 Alec Jeffreys discovered DNA fingerprinting 1989 Human genome sequenced by F. Collins and Lap-Chee Tsui  1995 Genome of H. influenza was sequenced 1996 yeast genome was sequenced 1998 Round worm genome was sequenced 2001 Human Genome was released by Human Timeline of Genome Project and Celera Genomics Notable simultaneously Discoveries 2003 Successful completion of human genome with 99% accuracy 2006 Marcus Pembrey and Olov Bygren Sex- specific, male-line transgenerational response. (epigenetics- heritable changes in gene expression)  Plant and Animal Improvement Medicine/Pharmaceuticals Applicatio n of Genetic counseling Genetics Legal applications Recombinant DNA Technology/ Genetic engineering  What are model organisms? DO YOU A model organism is a species that WANT TO BE has been widely studied, usually MODEL? because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages.  Many model organisms can breed in large numbers. Some have a very short generation time, which is the time between being born and being able to reproduce so that several generations can be followed at once Why are Mutants allow scientists to study certain characteristics or model diseases. These are model organisms that have undergone a change or mutation. in their DNA? that may result in a change in a organisms certain characteristic. useful in Some model organisms have similar genes. or similar-sized genomes? to humans. genetics Model organisms can be used to create highly detailed genetic research? maps: Genetic maps are a visual representation of the location of different genes on a chromosome? a bit like a real map but one where the key landmarks are areas of interest in the genome. For example, areas of DNA that differ between individuals in the same species (SNPs?) or genes. Examples of model organisms used to study genetics Yeast (Saccharomyces cerevisiae) Fruit fly (Drosophila melanogaster) Nematode worm (Caenorhabditis elegans) Western clawed frog (Xenopus tropicalis) Mouse (Mus musculus) Zebrafish (Danio rerio) “Our own genomes carry the story of evolution, written in DNA, the language of molecular genetics, and the narrative is unmistakable.” Kenneth R. Miller Thank you for listening For genetics modeling  HISTORICAL BACKGROUND Choose 3 scientist that you Assignment believe has significantly paved way for genetics and showcase their significant contributions. Concept map/infographic