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Galen of Pergamum
Galen was born in a wealthy and intellectual family. His father once had a dream, in which the Greek god of medicine, Ascelpius, told him that Galen must redirect his efforts into medicine and healing. Galen then became an elite physician. He was the first to discover that arteries carried blood and dissection of the human cranial nerves. https://www.famousscientists.org/galen/ -
Lamarck Develops Hypothesis of Evolution by Means of Acquired Characteristics
Lamarck believed an organism changes during life in order to adapt to its environment, those changes are then passed on to its offspring. Therefore saying, change is made when organisms want or need. One example is, he believed all giraffe had short necks, then when they couldn't reach their food they wanted, they stretched out there necks. He also believed that body parts that aren't being used will slowly disappear.(http://necsi.edu/projects/evolution/lamarck/lamarck/lamarck_lamarck.html) -
The Voyage of the HMS Beagle
22-year-old Charles Darwin received an amazing invitation to be apart of the HMS beagle, as the ship's naturalist. This voyage lasted about five years. The Beagle looked over the coast of South America. Darwin explored the continent and islands. He made and wrote down many observations he made of the animals, plants and geology. He also collected thousands of specimens. Darwin said, "by far the most important event in my life". (https://www.amnh.org/exhibitions/darwin/a-trip-around-the-world/) -
Louis Pasteur Refute Spontaneous Generation
Greek philosopher Aristotle, was one of the earliest scholars to express the theory of spontaneous generation. The theory states, the notion that life can arise from nonliving matter. The debate over this theory continued into the 19th century. Louis Pasteur a French chemist, set out experiments to disprove this theory. He then proposed "life only comes from life".(https://courses.lumenlearning.com/microbiology/chapter/spontaneous-generation/) -
The Origin of Species by Means of Natural Selection
Charles Darwin introduced the idea of natural selection, in his book "The Origin of Species by Means of Natural Selection". He thought that it can produce a small diversity within animal populations, and that should explain all of the diversity that's observed in biology. He made a great observation of this but not a great conclusion, as some believe. He concluded with that if it explains variety, all life must be related in some way. (https://www.allaboutscience.org/origin-of-species.htm) -
"Father of Genetics" Gregor Mendel
Gregor Mendel studied pea plants, from which he discovered the laws of inheritance. He concluded gene pairs define each inherited trait, offspring inherit one genetic allele from each parent (which unite in fertilization). Inheritance of traits are independent of each other. Genes express forms that are either dominant or recessive. It wasn't until after Mendel's time that his laws were rediscovered and understood.
(http://www.dnaftb.org/1/bio.html) -
Plasmodium Falciparum Causative Agent of Malaria
Maleria caused by the agent plasmodium falciparum is the most dangerous form of malaria. The life cycle of plasmodium begins with an infected female mosquito bites a human which released sporozoites. P. falciparum sporozoites enter the bloodstream and invade hepatocytes. It infects red blood cells which cause them to stick to blood vessels. This leads to the disfunction of multiple organs. http://scientistsagainstmalaria.net/parasite/plasmodium-falciparum -
Hardy & Weinberg Equation
Godfrey Hardy and Wilhelm Weinberg conducted different mathematical modeling based on probability. They developed a simple equation to discover the probable genotypes recurrence in a population and track their changes from one generation to another. It is best known as the Hardy-Weinberg equilibrium equation. (p2+2pq=q2=1)
https://www2.palomar.edu/anthro/synthetic/synth_2.htm -
Thomas Hunt Morgan Discovers Sex Linkage
Morgan began breeding the common fruit fly. He hoped to make new discoveries of large-scale mutations that would represent the emergence of new species. After breeding millions of fruit flies, he noticed 1 fruit fly with a different set of eye color. He then discovered Mendelian rules of inheritance of dominant and recessive traits could apply, discovering that eye color in the fruit fly is expressed as a sex-linked trait.
http://www.genomenewsnetwork.org/resources/timeline/1910_Morgan.php -
Bohr model of the atom structure
Niels Bohr was the first to discover that electrons travel in different orbitals around the nucleus, the number of electrons in the orbit will then determine the element's properties. The Bohr model has a small, positive nucleus surrounded by the electrons in their separate orbits. Bohr believed the orbits were stable and stationary. Bohr's model ultimately only works for hydrogen.
https://www.livescience.com/32016-niels-bohr-atomic-theory.html -
The Germ Theory of Disease is Published
The Germ theory states that particular microscopic organisms are the cause of specific diseases. Between 1850 and 1920 the theory grew, demonstrated and popularized in Europe and North American. This theory changed the theory and practice of medicine and the unraveling of disease. The Germ theory required public awareness not only of the germs but also the diseases. The public was therefore taught of the germs and how they can be passed on. (http://ocp.hul.harvard.edu/contagion/germtheory.html) -
Frederick Griffith's Transformation Experiment
Griffith was trying to find a vaccine against the Spanish flu. His experiment showed that bacteria was capable of transferring their genetic information by a procedure called transformation. In his experiment, which was composed of testing the effects of killed bacteria on live cells, was intended for developing a vaccine. However, he concluded that the bacterial stains, he experimented on, were capable of gene transfer.
http://www.brighthub.com/science/genetics/articles/43672.aspx -
DNA is the Genetic Material
Oswald Avery, Maclyn McCarty and Colin MacLeod obtained small amounts of highly purified transforming principle, analyzed and determined its identity as DNA to be the transforming principle from Frederick Griffith's bacterial transformation experiments. The purified substance gave a positive result in a chemical test used to detect DNA.
https://www.khanacademy.org/science/biology/dna-as-the-genetic-material/dna-discovery-and-structure/a/classic-experiments-dna-as-the-genetic-material -
Rosalind Franklin and Image 51
Rosalind Franklin improved X-ray crystallography unit at King's College in London. She obtained two sets of high-resolution photos of crystallized DNA fibers, one the fibers of DNA was more hydrated than the other. From these photos, she deduced that phosphates were on the outside of the DNA strands. Her colleague Wilkins showed one of the images "Image 51" to two scientists, Watson and Crick which helped them deduce the shape of DNA and publish their work.
http://www.dnaftb.org/19/bio-3.html -
Hershey & Chase Experiments
Alfred Hershey believed proteins was the molecule that carried genetic information. To test his hypothesis, him and his lab technician, Martha Chase determined to track the transfer of proteins and DNA between a virus and it's host. T2 bacteriophage delivered the genetic material. The virus with the largest bacteria formed was in the phosphorus. Phosphorus is found in DNA, proving Hershey's hypothesis wrong.(https://paulingblog.wordpress.com/2009/08/18/the-hershey-chase-blender-experiments/) -
Waston and Crick and the discovery of the double helix model of DNA structure
James D. Watson and Francis H.C. Crick were working on figuring out the structure of DNA when they were shown an X-ray photograph that belonged to Rosalind Franklin, which helped the scientists in their discovery of the structure of DNA. The two scientists determined the DNA structure was made of two DNA strands composed of monomer nucleotides in a spiral formation.
http://www.history.com/this-day-in-history/watson-and-crick-discover-chemical-structure-of-dna -
The Meselson-Stahl Experiment
Matt Meselson and Franklin Stahl grew E.coli in broth containing heavy nitrogen. They used density gradient centrifugation to separate molecules of DNA into bands. The bands of different generations were compared. From their experiment they concluded that each strand in DNA serves as a template for its complementary strand, called semi-soncervative DNA replication. https://www.khanacademy.org/science/biology/dna-as-the-genetic-material/dna-replication/a/mode-of-dna-replication-meselson-stahl-exp -
Nirenburg Cracks the Genetic Code
A young biochemist discovered the first "triplet", a sequence of three bases of DNA that codes for one of the 20 amino acids that serve as the building blocks of proteins. The breakthrough of this experiment came about when Nirenburg's colleague added "poly-U". This discovery decoded the genetic code. Nirenburg went about cracking down other triplets in the genetic code. A total of 35 by 1963 and over 60 by 1966.
http://www.genomenewsnetwork.org/resources/timeline/1961_Nirenberg.php -
Endosymbiosis is Described by Lynn Margulis
Lynn Margulis looked at the similarities of prokaryotes, eukaryotes and organelles and explained it as endosymbiosis. Endosymbiosis is a type of symbiosis where an organism lives inside of another, mutually benefiting form the relationship. She originally hypothesized that aerobic bacteria were ingested by anaerobic bacteria for survival advantages. Which resulted in a double-membrane bound organelle. https://www.biology.iupui.edu/biocourses/N100/2k2endosymb.html -
Apollo 11 Lands On The Moon
The morning of July 16th 1969; astronauts Neil Armstrong, Buzz Aldrin and Michael Collins take off in a three-stage-363-foot rocket. On their way to making history, Armstrong was greatly concerned of the landing. At 10:56pm EDT on July 20th, Armstrong gets ready to place the first step of man on the moon. He climbs down the latter and sets foot on the moon, saying, "That's one small step for man, one giant leap for mankind". (https://www.nasa.gov/mission_pages/apollo/apollo11.html) -
Hydrothermal Vents
Water seeps from the cracks of Earth's crust and rises through the ocean floor which causes geysers to from the hydrothermal vent. The minerals and metals from the vent react with the cold sea water to form a chimney around the vent. Unique communities of shrimp, crabs, and fish live around the vents. Instead of sunlight, these organisms live off of the hydrogen sulfide from the vents.
(http://wwf.panda.org/about_our_earth/blue_planet/deep_sea/vents_seeps/) -
Spliceosomes
Splicesomes are huge molecular complexes that were identified in yeast extracts as well as mammalian cells. They contain small nuclear RNAs (snRNAs or slurps) which aid in the removal on an intron. The splice some envelopes the RNA being sliced for initial transcription. It represents a potential regulatory step in eukaryotic gene expression.(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3119917/) -
Sanger Sequencing
Frederick Sanger developed the process of selective incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication. It is the most widely known sequencing method for about 25 years. This method is the classical "rapid DNA sequencing" technique. Special enzymes are used to combine short pieces of DNA, which end in selected "terminating" base, added to the stretch of the combined DNA. https://unlockinglifescode.org/timeline/11 -
Polymerase Chain Reaction
Kary B. Mullis discovered the technique of PCR, which makes copies of DNA. DNA polymerase synthesizes the new strand of DNA which is complementary to the template strand. DNA polymerase can add a nucleotide to the existing 3'OH group, it uses a primer to add the nucleotides. This allows scientists to amplify a specific spot on the template sequence. The specific sequence can make billions of copies.
https://www.ncbi.nlm.nih.gov/genome/probe/doc/TechPCR.shtml -
DNA Technology is Used to Convict Richard Bible
Arizona's first use of DNA technology helped to convict child-killer Richard Bible. Bible beat and killed a girl. Evidence found at the scene of the crime matched evidence from the inside of Bible's vehicle. DNA analysis was used to match the blood on Bible's shirt to the victim. The court allowed the new technology to be used in this case. Bible was found guilty of first-degree murder. http://www.abc15.com/news/crime/death-row-diaries-the-first-use-of-dna-technology-in-an-arizona-murder-case -
The Innocence Project
The Innocence Project was founded by Peter Neufeld and Barry Scheck at Cardozo School of Law, abolishing the wrongly convicted through DNA testing. The mission of this project is to free the number of people that have been or are incarcerated for crimes they did not commit. Also reforming the system for their unjust imprisonment. https://www.innocenceproject.org/about/ -
Sheep Clone "Dolly"
Scientists from the Rosalin Institute in Scotland used an udder cell from one sheep which was injected into an unfertilized egg from another sheep. The cells were cultured and developed into an embryo. The embryo was implanted into 13 surrogate mothers, only one pregnancy made it to full term, Dolly. Most importantly cloning technology has led to new medicines and improved developments in genetics.
(http://www.animalresearch.info/en/medical-advances/timeline/cloning-dolly-the-sheep/) -
Sahelanthropus Tchadensis Fossil Discovery
Sahelanthropus Tchadensis is a specie that lived in West-Central Africa (Chad) sometime between 7 and 6 million years ago. It is one of the oldest known species in the human family tree. French paleontologist Michael Brunet led a research team and discovered some fossils. By looking at the fossils found, researchers believe this species walked upright because of the foramen magnum. (http://humanorigins.si.edu/evidence/human-fossils/species/sahelanthropus-tchadensis) -
Human Genome Project
The Human Genome Project was a global research project. The goal was to complete a mapping and grasping of all the genes of human beings. In 1911, Alfred Sturtevant knew he had to map the locations of the fruit fly. This started the human genome project. The International Human Genome Sequencing Consortium printed the first draft in a journal, with a sequence of the entire genome's three billion base pairs. (https://www.genome.gov/12011238/an-overview-of-the-human-genome-project/) -
CRISPr/CAS9
CRISPR-Cas9 is used to identify the genes that lead to failing pregnancies. A target specific RNA guides Cas9 to the target site on the genomic DNA. Double stranded breaks can than be repaired by homologous recombination or nonhomologus end joining. A DNA template is then used to repair the broken ends of the DNA. The sequence is inserted to identify indells. http://www.clontech.com/VG/Products/Genome_Editing/CRISPR_Cas9/Technical_Notes/Indel_Identification
