RGENETICS.pdf

BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B Genetics is one of the most rapidly advancing fields of science, have significant economic and ethical implications, Importance of Genetics Genes influence our physical features. These in turn influence our lives. Genes contribute to intellige...

BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B Genetics is one of the most rapidly advancing fields of science, have significant economic and ethical implications, Importance of Genetics Genes influence our physical features. These in turn influence our lives. Genes contribute to intelligence and personality Genes are fundamental to who and what we are Genes are important in agriculture Genes are important in pharmaceutical industry, biotechnology industry, and medicine Genes are important in development The Early Use and Understanding of Genetics The first evidence that people understood and applied the principles of heredity in earlier times is found in the domestication of plants and animals, which began between approximately 10,000 and 12,000 years ago in the Middle East. The first domesticated organisms included wheat, peas, lentils, barley, dogs, goats, and sheep. PANGENESIS Inheritance of acquired characteristics. Traits acquired in a person’s lifetime become incorporated into that person’s hereditary information and are passed on to offspring; for example, people who developed musical ability through diligent study would produce children who are innately endowed with musical ability. 1 RUSSELL M. BAN,BS.EdS II  BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B Preformationism. Inside the egg or sperm there exists a fully formed miniature adult, a homunculus, which simply enlarges during development. Preformationism meant that all traits were inherited from only one parent—from the father if the homunculus was in the sperm or from the mother if it was in the egg. Blending inheritance. The traits of offspring are a blend, or mixture, of parental traits. This idea suggested that the genetic material itself blends, much as blue and yellow pigments blend to make green paint. It also suggested that after having been blended, genetic differences could not be separated in future generations, just as green paint cannot be separated into blue and yellow pigments. The Rise of the Science of Genetics 1676 Nehemiah Grew reported that plants reproduce sexually by using pollen from the male sex cells  1676 Nehemiah Grew reported that plants reproduce sexually by using pollen from the male sex cells 1859 Charles Darwin put forth the theory of evolution through natural selection and published his ideas in On the Origin of Species. Darwin recognized that heredity was fundamental to evolution, and he conducted extensive genetic crosses with pigeons and other organisms 1879 W alther Flemming observed the division of chromosomes and published a superb description of mitosis 1885 Biologists generally recognized that the cell nucleus contains the hereditary information  W eismann proposed the germ-plasm theory, which holds that the cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm.  1900 The experiment with pea plants by Gregor Mendel, which revealed the laws of heredity, was rediscovered  1902 W alter Sutton proposed that genes are located on chromosomes  1910 Thomas Hunt Morgan discovered the first genetic mutant of fruit flies and used fruit flies to unravel many details of transmission genetics (how an individual inherits its genetic makeup and how it passes its genes to the next generation). 2 RUSSELL M. BAN,BS.EdS II  BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B  1930s The foundation for population genetics (how the genetic composition of groups of individuals of the same species (populations) changes over time and space) was laid when geneticists begin to integrate Mendelian genetics and evolutionary theory  1940s Geneticists began to use bacteria and viruses for detailed study of the organization and structure of genes. At about the same time, evidence accumulated that DNA was the repository of genetic information.  1953 James W atson, Francis Crick, Maurice W ilkins, and Rosalind Franklin – described the three-dimensional structure of DNA (Era of molecular genetics); the era of molecular genetics (concerns the chemical nature of the gene itself: how genetic information is encoded, replicated, and expressed).  1966 Scientists had figured out the molecular structure of DNA and the technique by which it controls the amino acid sequence of proteins  1973 First recombinant DNA experiments were conducted  1977 Methods for rapidly sequencing DNA were initially developed, which later allowed whole genomes of humans and other organisms to be determined  1983 The polymerase chain reaction, a technique for quickly amplifying tiny amounts of DNA, was developed by Kary Mullis and others  1990 The Human Genome Project was launched  1995 The first complete DNA sequence of a free-living organism—the bacterium Haemophilus influenzae—was determined  1996 Complete sequence of a eukaryotic organism (yeast) was reported  2000 A rough draft of the human genome sequence was reported  2003 The human genome sequence was essentially completed, ushering in a new era in genetics  Today, the genomes of numerous organisms are being sequenced, analyzed, and compared.  Genes are segments of deoxyribonucleic acid (DNA) that determine our traits; DNA is a molecule in cells that carries the genetic information; chromosomes are long, bundled strands of DNA 3 RUSSELL M. BAN,BS.EdS II  BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B Some Fundamental Genetic Concepts Cells are of two basic types: eukaryotic and prokaryotic. Prokaryotic cells lack a nuclear membrane and do not generally possess membrane-bounded cell organelles, whereas eukaryotic cells are more complex, possessing a nucleus and membrane-bounded organelles such as chloroplasts and mitochondria. The gene is the fundamental unit of heredity. Genes come in multiple forms called alleles. A gene that specifies a characteristic may exist in several forms, called alleles. Genes confer phenotypes. Traits are not inherited directly. Rather, genes are inherited and, along with environmental factors, determine the expression of traits. The genetic information that an individual organism possesses is its genotype; the trait is its phenotype. Genetic information is carried in DNA and RNA. Genetic information is encoded in the molecular structure of nucleic acids, which come in two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Genes are located on chromosomes. The vehicles of genetic information within a cell are chromosomes, which consist of DNA and associated proteins. Replicated chromosomes separate through the processes of mitosis and meiosis. Genetic information is transferred from DNA to RNA to protein. Mutations are changes in genetic information that can be passed from cell to cell or from parent to offspring. Many traits are affected by multiple factors. Many traits are affected by multiple genes that interact in complex ways with environmental factors. Evolution is genetic change. 4 RUSSELL M. BAN,BS.EdS II BACHELOR OF SECONDARY EDUCATION MAJOR IN SCIENCE 2-B 5 RUSSELL M. BAN,BS.EdS II