Genetics: Past, Present, and Future PDF

GENETICS: PAST, PRESENT and FUTURE  History of Genetics People have known about inheritance for a long time. ✓ Children resemble their parents ✓ Domestication of animals and plants, selective breeding for good characteristics ✓ Sumerian horse breeding records ✓ Egyptian data palm breed...

GENETICS: PAST, PRESENT and FUTURE  History of Genetics People have known about inheritance for a long time. ✓ Children resemble their parents ✓ Domestication of animals and plants, selective breeding for good characteristics ✓ Sumerian horse breeding records ✓ Egyptian data palm breeding ✓ Ability to indentify a person as a member of a particular family by certain physical traits  Different Old Theories explained the Similarities and Dissimilarities between Individuals ✓ Blending theory The mixture of sperm and egg resulted in progeny that were a “blend” of two parents’ characteristics. ✓ Acquired characters inheritance (Jean Baptiste Lamarck) Individuals inherit traits are strengthened by their parents ✓ Pangenesis (Charles Darwin) The cells excreted gemmules then collected and concentrated in the reproductive organ. Fathers and mother gemmules blended to form an embryo  Different Old Theories explained the Similarities and Dissimilarities between Individuals ✓ Performation and Epigenesis Organism develop by expressing information carried in their heredity material ✓ Cell Theory (Hooke, Leewenhoek, Schleiden, Schwann, Virchow) 1. All living things are composed of one or more cells 2. Cells are the basic units of structure and function in living things (Schleiden and Schwann, 1839) 3. New cells are produced from existing cells (Virchow, 1858)  Mid 1800’s Discoveries Three major events in the mid-1800’s led directly to the development of modern genetics. 1859: Charles Darwin publishes The Origin of Species, which describes the theory of evolution by natural selection. This theory requires heredity to work. 1866: Gregor Mendel publishes Experiments in Plant Hybridization, which lays out the basic theory of genetics. It is widely ignored until 1900. 1871: Friedrich Miescher isolates “nucleic acid” from pus cells.  Gregor Mendel (1822-1884) Systematically recorded results of crosses Theorized on nature of hereditary material Postulate mechanism of transfer of "Elementen" governing traits  Mendel’s Work with Peas a. He selected strains that differed in particular traits (e.g., smooth or wrinkled seeds, purple or white flowers) b. After making genetic crosses, he counted the appearance of traits in the progeny and analyzed the results mathematically. c. He concluded that each organism contains two copies of each gene, one from each parent, and that alternative versions of the genes (alleles) exist  Mendel’s Work with Peas 4. He deduced that the factors (now called genes) segregate randomly into gametes (Mendel’s first law, the Principle of Segregation). 5. The two factors for a particular trait assort independently of factors controlling other traits (Mendel’s second law, the Principle of Independent Assortment). 6. An example is seed color in peas: i. True-breeding plants with yellow seeds (YY) are crossed with true-breeding plants with green seeds (yy). ii. The progeny (F1) have yellow seeds, and a heterozygous genotype (Yy). iii. When the progeny self-pollinate, the F2 contains 3 yellow:1 green, with genotypic ratios of 1 YY : 2 Yy : 1 yy.  Major Events in the 20th Century 1900: rediscovery of Mendel’s work by Robert Correns, Hugo de Vries, and Erich von Tschermak. 1902: Archibald Garrod discovers that alkaptonuria, a human disease, has a genetic basis. 1904: Gregory Bateson discovers linkage between genes. Also coins the word “genetics”. 1910: Thomas Hunt Morgan proves that genes are located on the chromosomes (using Drosophila). 1918: R. A. Fisher begins the study of quantitative genetics by partitioning phenotypic variance into a genetic and an environmental component.  Thomas Hunt Morgan Thomas Hunt Morgan: early 1900’s – Worked at Columbia University; later at CalTech – Studied fruit fly eye color, determining that trait was sex-linked – Won the Nobel Prize in 1933 for his work on chromosomes and genetics Thomas Hunt Morgan  Thomas Hunt Morgan By this point, it was known that genetic material was located on a chromosome This genetic material was in discrete units called genes It was NOT known whether the gene was simply a protein, or whether it was composed of DNA  More 20th Century Events 1926: Hermann J. Muller shows that X-rays induce mutations. 1944: Oswald Avery, Colin MacLeod and Maclyn McCarty show that DNA can transform bacteria, demonstrating that DNA is the hereditary material. 1953: James Watson and Francis Crick determine the structure of the DNA molecule, which leads directly to knowledge of how it replicates  More 20th Century Events 1966: Marshall Nirenberg solves the genetic code, showing that 3 DNA bases code for one amino acid. 1966: How DNA worked to control the activities of the cell had all been worked out [ DNA >> RNA >> protein] 1972: Stanley Cohen and Herbert Boyer combine DNA from two different species in vitro, then transform it into bacterial cells: first DNA cloning.  More 20th Century Events 1973 – Recombinant DNA molecules formed. 1977 – Sequencing of DNA achieved. 1983 – PCR technique developed. 1990 – First successful gene therapy. 1995 – The Human Genome Project (HGP) gets underway. 2003 – HGP essentially completed. James Watson and Francis Crick  James Watson and Francis Crick Used wire models to conform with the measurements that Franklin and Wilkins had come up with Determined the structure to be a double helix Lead to understanding of mutation and relationship between DNA and proteins at a molecular level 1959 – “Central Dogma” – DNA→RNA→protein Birth of Central Dogma of Biology  What is Genetics? Genetics is a field of biology that studies how traits are passed from parents to their offspring. The passing of traits from parents to offspring is known as heredity, therefore, genetics is the study of heredity.  Branches of Genetics 1. Transmission genetics Classical or Mendelian genetics 2. Molecular genetics – chromosomes, DNA, regulation of gene expression – recombinant DNA, biotechnology, bioinformatics, genomics, proteomics 3. Population, evolutionary genetics allelic frequencies in populations effects of migration study relatedness of taxa via DNA and protein analysis 4. Quantitative genetics – effects of many genes 5. Biochemical genetics- the study of the fundamental relationships between genes, protein, and metabolism. This involves the study of the cause of many specific heritable diseases 6. Cytogenetics- is a branch of genetics that is concerned with the study of the structure and function of the cell, especially the chromosomes 7. Behavioral genetics- is the field of study that examines the role of genetics in animal (including human) behavior 8. Developmental genetics is the study of the process by which organisms grow and develop 9. Conservation genetics- is an interdisciplinary science that aims to apply genetic methods to the conservation and restoration of biodiversity 10. Ecological genetics is the study of genetics in natural populations 11. Genetic engineering is the direct manipulation of an organism's genome using biotechnology. New DNA may be inserted in the host genome by first isolating and copying the genetic material of interest using molecular cloning methods to generate a DNA sequence, or by synthesizing the DNA, and then inserting this construct into the host organism.  Metagenics is the practice of engineering organisms to create a specific enzyme, protein, or other biochemicals from simpler starting materials. The genetic engineering of E. coli with the specific task of producing human insulin from starting amino acids is an example. Genomics is a discipline in genetics that applies recombinant DNA, DNA sequencing methods, and bioinformatics to sequence, assemble, and analyze the function and structure of genomes (the complete set of DNA within a single cell of an organism  12. Human genetics- is the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics and genetic counselling. 13. Medical genetics- is the specialty of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from Human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, but medical genetics refers to the application of genetics to medical care. 14. Microbial genetics- This involves the study of the genotype of microbial species and also the expression system in the form of phenotypes.It also involves the study of genetic processes taking place in these micro organisms i.e., recombination etc 15. Molecular genetics- is the field of biology and genetics that studies the structure and function of genes at a molecular level. Molecular genetics employs the methods of genetics and molecular biology to elucidate molecular function and interactions among genes. It is so-called to differentiate it from other sub fields of genetics such as ecological genetics and population genetics.  Application of Genetics Medicine Food Animal and plant agriculture Conservation Environment Psychology/Social Sciences Forensics  Future of Genetics >> The end of sex and the future of human reproduction >> Gene therapy >> Gene editing for treating diseases >> Cloning higher organisms >> Food production with less farming techniques  Future of Genetics >> Democratizing genetic information >> More effective crime solving in the society >> Prediction of trends in conservation And biodiversity