History of Genetics

By anasnavia

  • The Beginning of Natural Selection

    Charles Darwin begins his investigation on Natural Selection and devotes his life to work on the theory. He later publishes the theory.

  • Gregor Mendel breeding experiments

    In 1856 Gregor Mendel began his experiment for the trace of inheritance patterns of certain traits in pea plants.

  • Theory of Natural Selection

    In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He defined natural selection as the ‘process that results in the adaptation of an organism to its environment by means of reproducing changes to its genotype’.

  • Basic Principles of Inheritance

    G. Mendel described the basic principles of inheritance:
    -Fundamental theory of heredity
    -Principle of segregation
    -Principle of independent assortment

  • Heredity Transmitted in Units

    After his initial experiments with pea plants, Mendel settled to study seven traits that seemed to be inherited independently of other traits: seed shape, flower color, seed coat tint, pod shape, unripe pod color, flower location and plant height. The study showed that, when breeding different varieties were crossed to each other, in the second generation, one in four pea plants had purebred recessive traits, two out of four were hybrids, and one out of four were purebred dominant.

  • Nucleus Contains Necessary Factors for Heredity

    E. Haeckel proposed that the nucleus contains the factors necessary for heredity.

  • Isolation of DNA

    Frederick Miescher collects used bandages and washes off the pus. After experimenting for some time, he isolates a new molecule called nuclein, which means he isolated DNA from cells.

  • The Chemical Property of DNA

    F. Miescher described some of the chemical property of DNA (C29H49N9P3O22). At that time proteins were supposed to be the hereditary material.

  • Statistical Approach to Understanding Inheritance

    Francis Galton undertook studies of how various traits might be transmitted from parent to offspring. He injected rabbits with blood of other rabbits with different color coats, tested a speculative theory known as “pangenesis”. As Galton soon realized, that theory- in which particles in the blood were thought to carry hereditary information- was incorrect.

  • Mitosis

    Walther Flemming discovered that certain types of dyes revealed a threadlike material in the nucleus of a cell. Applying the dyes showed that the cell’s nucleus changed during cell division. He showed that the threads (that were later called chromosomes), shortened and split longitudinally into two halves. He called this process mitosis.

  • Cell Division

    Walther Flemming, Anton Schneider, Eduard Strasburger and others in the late 1879s and 1880s led to observations that are almost intuitively evident to us today:
    -Chromosomes are duplicated during cell division.
    -Each daughter cell receives the same number of chromosomes.
    -Gametes contain half the number of chromosomes as an adult cell
    -Fertilization involves the fusion of the nuclei of sperm and egg
    -The resulting zygote had the full chromosome complement.

  • Walther Flemming

    Walther Flemming, a German anatomist investigating the structure of cells, discovers a substance he calls chromatin. He notices that, during cell division, this substance separates into threadlike strings, which become known as chromosomes.

  • Nucleic Acids

    Altmann names "nucleic acids”.

  • The Rediscovery of Mendel's Work

    Botanists DeVries, Correns, and von Tschermak independently rediscover Mendel’s work while doing their own work on the laws of inheritance. The increased understanding of cells and
    chromosomes at this time allowed the placement of Mendel’s abstract ideas into a physical context

  • Chromosome Theory of Inheritance

    Sir. Archibald Edward Garrod became the first person to associate Mendel’s theories with a human disease. By studying the human disorder alkaptonuria, he collected family history information from his patients. Through discussion with William Bateson (Mendelian advocate) he concluded that alkaptonuria was a recessive disorder and in 1902 he published a book called “Incidence of Alkaptonuria A Study in Chemical Individuality”.

  • Chromosomes Contain Genetic Material

    Walter Sutton proposes that chromosomes contain genetic material.

  • Characteristics of the 4 Types of DNA

    All 4 bases in DNA now characterized, (incl. T & C) in roughly equal amounts.

  • Enzymes in Protein

    Enzymes found to be made from proteins. Archibald Garrod proposes chromosomes affects enzymes.

  • Thomas Hunt Morgan

    Morgan demonstrated that genes are carried on chromosomes and are the mechanical basis of heredity.

  • Chromosomes Carry a Gene

    In 1911 a Columbia university student Alfred Sturtevant wondered if the frequency of crossing-over between genes during meiosis might be a clue to the location of the genes. Sturtevant reasoned that the farther apart two genes were on a chromosome, the more likely it would be that a crossover event would occur between them.If two genes are close together, then crossovers between them should be rare. If two genes are far apart, then the crossovers between them should be more common.

  • Discovery of Mutant Traits

    Intensive work led Morgan to discover more mutant traits—some two dozen between 1911 and 1914. With evidence drawn from cytology he was able to refine Mendelian laws and combine them with the theory—first suggested by Theodor Boveri and Walter Sutton—that the chromosomes carry hereditary information. In 1915, Morgan and his colleagues published The Mechanism of Mendelian Heredity.

  • Artificial Gene Mutations

    Hermann J. Muller Used x-rays to cause artificial gene mutations in Drosophila.

  • Diplococcus

    Fred Griffith Proposed that some unknown "principle" had transformed the harmless R strain of Diplococcus to the virulent S strain.

  • Cytological proof of crossing over

    Harriet B. Creighton Barbara McClintock Demonstrated the cytological proof for crossing-over in maize.

  • Discovery of DNA in chromosomes

    1933: Jean Brachet is able to show that DNA is found in chromosomes and that RNA is present in the cytoplasm of all cells.

  • Thomas Morgan Received a Nobel prize

    1933: Thomas Morgan received the Nobel prize for linkage mapping. His work elucidated the role played by the chromosome in heredity.

  • Gene Effect

    George Beadle Edward Tatum Irradiated the red bread mould, Neurospora, and proved that the gene produces its effect by regulating particular enzymes.

  • Purified the Transforming Principle

    Oswald Avery Colin MacLeod Maclyn McCarty Reported that they had purified the transforming principle in Griffith's experiment and that it was DNA.

  • Jumping Genes

    Barbara McClintock, using corn as the model organism, discovered that genes can move around on chromosomes. This shows that the genome is more dynamic than previously thought. These mobile gene units are called transposons and are found in many species.

  • Genes are Made of DNA

    Alfred Hershey & Martha Chase show that only the DNA of a virus needs to enter a bacterium to infect it, providing strong support for the idea that genes are made of DNA.

  • DNA Double Helix

    Francis H. Crick and James D.Watson described the double helix structure of DNA. They receive the Nobel Prize for their work in 1962.

  • 46 Human Chromosomes

    Joe Hin Tjio defines 46 as the exact number of chromosomes in human cells.

  • DNA Copying Enzyme

    Arthur Kornberg and colleagues isolated DNA polymerase, an enzyme that would later be used for DNA sequencing.

  • Cause of Disease Traced to Alteration

    Vernon Ingram discovers that a specific chemical alteration ina hemoglobin protein is the cause of sickle cell disease.

  • Semiconservative Replication of DNA

    Matthew Meselson and Franklin Stahl demonstrate that DNA replicates semi conservatively: each strand from the parent DNA molecule ends up paired with a new strand from the daughter generation.

  • Chromosome Abnormalities Identified

    Jerome Lejeune and his colleagues discover that Down Syndrome is caused by trisomy 21. There are three copies, rather than two, of chromosome 21, and this extrachromosomal material interferes with normal development.

  • First Screen for Metabolic Defect in Newborns

    Robert Guthrie develops a method to test newborns for the metabolic defect, phenylketonuria (PKU).

  • mRNA Ferries Information

    Sydney Brenner, François Jacob and Matthew Meselson discover that mRNA takes information from DNA in the nucleus to the protein-making machinery in the cytoplasm.

  • Genetic Code Cracked

    Marshall Nirenberg and others figure out the genetic code that allows nucleic acids with their 4 letter alphabet to determine the order of 20 kinds of amino acids in proteins.

  • First Restriction Enzyme Described

    Scientists describe restriction nucleases, enzymes that recognize and cut specific short sequences of DNA. The Resulting fragments can be used to analyze DNA, and these enzymes later became an important tool for mapping genomes.

  • First Recombinant DNA

    Scientists produce recombinant DNA molecules by joining DNA from different species and subsequently inserting the hybrid DNA into a host cell, often a bacterium.

  • First Animal Gene Cloned

    Researchers fuse a segment of DNA containing a gene from the African clawed frog Xenopus with DNA from the bacterium E. coli and placed the resulting DNA back into an E. coli cell. There, the frog DNA was copied and the gene it contained directed the production of a specific frog protein.

  • DNA Sequencing

    Two groups, Frederick Sanger and colleagues, and Alan Maxam and Walter Gilbert, both develop rapid DNA sequencing methods. The Sanger method is most commonly employed in the lab today, with colored dyes used to identify each of the four nucleic acids that make up DNA.

  • First Genetic Engineering Company

    Herbert Boyer founds Genentech.The company produces the first human protein in a bacterium, and by 1982 markets the first recombinant DNA drug, human insulin.

  • Introns Discovered

    Richard Roberts’ and Phil Sharp’slabs show that eukaryoticgenes contain many interruptions called introns. These non-coding regions do not directly specify the amino acids that make protein products.

  • First Transgenic Mice and Fruit Flies

    Scientists successfully add stably inherited genes to laboratory animals. The resulting transgenic animals provide a new way to test the functions of genes.

  • GenBank Database Formed

    Scientists begin submitting DNA sequence data to a National Institutes of Health (NIH) database that is open to the public.

  • First Disease Gene Mapped

    A genetic marker for Huntington’s disease is found on chromosome 4.

  • PCR Invented

    The polymerase chain reaction,or PCR, is used to amplify DNA. This method allows researchers to quickly make billions of copies of a specific segment of DNA, enabling them to study it more easily.

  • First Time a Disease Gene is Positionally Cloned

    A method for finding a gene without the knowledge of theprotein it encodes is developed. So called, positional cloning can help in understanding inherited disease, such as musculardystrophy.

  • First Human Genetic Map

    The first comprehensive genetic map is based on variations inDNA sequence that can be observed by digesting DNA withrestriction enzymes. Such a map can beused tohelp locategenes responsible for diseases.

  • Yeast Artificial Chromosomes

    Scientists discover that artificial chromosomes made from yeast can reliably carry large fragments of human DNA containing millions of base-pair pieces. Earlier methods used plasmids and viruses, which can carry only a few thousand base-pair pieces. The ability to deal with much larger pieces of DNA makes mapping the human genome easier.

  • Microsatellites Are New Genetic Markers

    Repetitive DNA sequences called micro satellites are used as genetic landmarks to distinguish between people. Another type of marker, sequence–tagged sites, are unique stretches of DNA that can be used to make physical maps of human chromosomes.

  • Launch of the Human Genome Project 9

    The Department of Energy and the National Institutes ofHealth announce a plan for a 15-year projecttosequence thehuman genome. This will eventuallyresult in sequencing all 3.2billion lettersofthe human genome.

  • ESTs, Fragments of Genes

    An expressed-sequence tag (EST) anidentified piece of a gene,is made by copying a portion of a messenger RNA (mRNA)molecule. As such, ESTs provide a waytofocus onthe“expressed”portion ofthegenome, which is lessthan one-tenth.

  • Second-Generation Genetic Map of Human Genome

    A French team builds a low-resolution, microsatellite genetic map of the entire human genome. Each generationofthe maphelps geneticists more quickly locate disease genes onchromosomes.

  • Ban on Genetic Discrimination in the Workplace

    Protection under the American withDisabilities Act isextended to cover discrimination based on genticinformation.

  • Mouse Genetic Map Completed

    The lab mouse is valuable for genetics research because humans and mice share almost all of their genes, and the genes on average are 85% identical.The mouse genetic increases the utility of mice as animal models for genetic disease in humans.

  • E. coli Genome Sequenced

    The complete sequence of the E. Coli genome will help scientists learn even more about this extensively studied bacterium.

  • M. tuberculosis Bacterium Sequenced

    Mycobacterium tuberculosis causes the chronic infectious disease tuberculosis. The sequencing of this bacterium is expected to help scientists develop new therapies to treat the disease.

  • Roundworm C. elegans Sequenced

    The first genome sequence of a multicellular organism, the roundworm, Caenorhabditis elegans, is completed.

  • Chromosome 22 Sequenced

    The first finished, full-length sequence of a human chromosome is produced. Chromosome 22 was chosen to be first because it is relatively small and had a highly detailed map already
    available. Such a map is necessary for the clone by clone sequencing approach.

  • Human Genome Working Draft Completed

    By the end of Spring 2000, HGP researchers sequence 90 percent of the human genome with 4-fold redundancy. This working draft sequence is estimated to be 99.9% accurate.

  • Mouse Genome Working Draft Assembled and Analyzed

    The Mouse Genome Sequencing Consortium publishes an assembled draftand comparative analysis of the mouse genome. This milestone was originally planned for 2003.

  • Rat Genome Working Draft Completed

    By Fall 2002, researchers sequence over 90%of the rat genome with over 5-fold redundancy.

  • Completion of the Human Genome Sequencing

    The finished human genome sequence will be at least 99.99% accurate.

  • First use of transcription activator

    Transcription activator-like effector nucleases (or TALENs) are first used to cut specific sequences of DNA.

  • Genome is sequenced in outer space for the first time

    A genome is sequenced in outer space for the first time, with NASA astronaut Kate Rubins using a MinION device aboard the International Space Station.

  • Protein derived from parasite has potential to alleviate debilitating disease

    Medical researchers have turned the tables on Schistosoma haematobium, a parasitic worm that freeloads in humans, by using a protein derived from the parasite as a therapeutic molecule to reduce bleeding and pain associated with chemotherapy-induced hemorrhagic cystitis.