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150 BCE
Galen of Pergamon
Galen theorized that human mood differences are because of an imbalance in bodily fluids like blood, yellow bile, black bile, and phlegm. He was also the first to state the differences between venous and arterial blood. He was also a gifted surgeon and he could treat cataracts, which wasn't a treatment used for centuries after his death. -
Lamarck Hypothesis
Lamarck introduced his hypothesis called "Inheritance of acquired characteristics" in 1809, well before Darwin published his book. He hypothesized that physiological changes over time can be passed down to descendants. Hippocrates and Aristotle also noted these ideas but Lamarck made them widely known and accepted. He observed that the younger the fossil, the more similar it was to modern species. Wikipedia -
HMS Beagle
HMS Beagle arrived in Madeira where Darwin was too ill to leave ship. Then went to Tenerife, the crew couldn't disembark due to a cholera outbreak. Next was Camp Verde islands - Darwin researched cuttle-fish. It crossed the equator & into Fernando de Noronha where Darwin noted the volcanic nature. Then to Salvador, he noticed tubelike creatures on the ocean floor. Next: Rio de Janeiro Darwin and Lennon explored 100 miles of tropical forest. pg -
Germ Theory
Robert Koch further developed the germ theory by his 4 postulates which state that a certain organism can inflict disease. He created these from his work with anthrax. They were created to identify pathogens that couldn't be treated with the period techniques. It was noted that some disease that are infectious did not fulfill his postulates of the time, and still don't to this day. Germ theory -
Origin of Species
Charles Darwin published a book, Origin of Species, in which the initial print was sold out. He traveled to the coast of South America & Galapagos Islands in the 1830's. He studied finches and tortoises in the area and how they adapted. He stated that the species evolve through natural selection. His book was met with praise and conflict. genome.gov -
Pasteur refutes spontaneous generation
Louis Pasteur discovered that fermentation and growing microorganisms in broths didn't happen by spontaneous generation. He introduced boiled liquid to air in vessels that had a filter so that nothing could pass through. He also used ones without a filter at all with air coming through a long tube that wouldn't pass dust particles. Nothing grew in the brews and that meant that living things came from outside on dust. wikipedia -
Mendel & pea plants
Mendel measured their height, flower color, seed color, and seed shape through inheritance. He used 2 pure-breed plants w/ short & tall heights. He counted how many plants showed a certain trait and he found similarities in all traits he measured. He presented that flower color, height, seed shape were controlled by heritable factors in 2 different versions (dominant and recessive). Mendel -
Plasmodium falciparum is described as the causative agent of malaria
Charles Louis Alphonse Laveran identified that the parasite, Plasmodium falciparum is a pathogen of malaria in 1880. He renamed it to Oscillaria malariae. He won the Nobel Prize in Physiology or Medicine for his discovery and research in 1907. -
Hardy-Weinberg equation
Hardy and Weinberg came up with the equation to find out the population at an equilibrium. They both independently came up with basic principles for population genetics which is why it is now called the Hardy-Weinberg equation. HW -
T. Hunt Morgan discovers sex-linkage
Thomas Hunt Morgan noticed that a male fruit fly didn't have the normal characteristics he had seen previously when he observed it through a hand lens. He tests red-eyed and white-eyed fruit flies for different traits that may be inherited differently. He established the chromosomal theory of hereditary because of the results he had. -
Bohr Model
The Bohr Model, as introduced by Niels Bohr and Ernest Rutherford in 1913, shows that the atom is a small and positively charged nucleus. It is surrounded by electrons that circle the nucleus. This was a breakthrough for Atomic Physics. -
Frederick Griffith - Process of Transformation
Griffith mixed killed S with alive R and introduced the combination to mice, which then died. He studied the mouse's tissue and found that it had live bacteria with shells like S that were smooth. These were able to kill mice in the future, and continued to do so over time. He stated that something in the bacteria had transformed. Griffith -
Avery, MacLeod, McCarty discovery
Avery and his colleagues killed the bacteria Pneumococcus w/ heat and removed the saline. After using chloroform, the polysaccharides were hydrolyzed with an enzyme. Then, they ran biochemical tests using trypsin, chymotripsin, ribonuclease to make sure it wasn't RNA and the sample wasn't affected. This meant that it wasn't RNA but was in fact DNA. -
Image 51
Raymond Gosling, under Rosalind Franklin, took an image using X-ray diffraction and it helped prove many theories of the structure of DNA. The image was taken of DNA and was done so at the King's College London. -
Hershey-Chase Experiments
The two researchers set out to prove that DNA is the carrier for genetic information and not protein. They reviewed the transfer of proteins and DNA in a virus and a host. They infected their samples with E. coli and used Phosphorus-32 in their first test, and sulfur for the second. They saw that the protein shell was not necessary for genetic material to be inserted. PaulingBlog -
Watson & Crick Double Helix
The two started in 1951 to create a 3d model of a gene. In February of 1953, they put two bases in their cardboard model by moving a hydrogen atom from one position to another so it bonded with oxygen and then bonded with nitrogen. Watson noticed that when A paired w/ T, it resembled C pairing with G. This created the double helix ladder that is now known today as DNA. Watson Crick -
Meselson and Stahl work with DNA replication
The experiment is an experiment by Matthew Meselson and Franklin Stahl which helped Watson and Crick's hypothesis that DNA replication was semiconservativ - about two strands of DNA separate during replication. -
Nirenberg cracks genetic code
Marshall Nirenberg and Heinrich Matthaei performed an experiment on 5/15/1961 in which they deciphered the first of 64 codons in the genetic code. They used nucleic acid homopolymers to translate specific amino acids. -
Endosymbiosis
Lynn Margulis studied the structure of cells in the 1960s. She theorized that cell organelles like mitochondira and chloroplasts were previously independent bacteria. She stated that a significant event in history probably merged the two or more through symbiosis. -
Apollo 11
Apollo 11 set out with the goal to become the 1st lunar exploration by JFK. This mission was carried out by astronauts Neil Armstrong and Buzz Aldrin. During this venture, medallions were left on the surface of the moon to commemorate astronauts and cosmonauts who died during Apollo 1 and other accidents. They spent 21 hours 36 minutes on the surface. They landed back on the Earth on July 24,1969 in the Pacific Ocean.Nasa site -
Spliceosomes were discovered
The Sharp and Roberts lab discovered that genes in higher organisms "split" or can be present in several parts of the DNA structure. Phillip Sharp came up with the name "splicing" and it then turned the genes into "spliceosomes". -
Sanger Technique
The Sanger technique is a method of DNA sequencing that was developed by Frederick Sanger. It selectively incorporates chain-terminating dideoxynucleotides by DNA polymerase during vitro DNA replication. The DNA sample is divided twice to create four reactions. Sanger -
Deep Sea Hydrothermal Vents
In 1977, scientists noticed temperature spikes in their data along the coast of the Galapagos Islands. Their temperatures ranged from freezing to 750F in a short span. They discovered deep sea hydrothermal vents in this area that are like geysers or hot springs along the ocean floor. -
Kary Mullis develops Polymerase Chain Reaction
Kary Mullis invented the Polymerase Chain Reaction (PCR) in 1958 while working as a chemist for a biotechnology firm in California. He placed a small amount of DNA containing desired gene into a test tube. Then he introduced nucleotides to the test tube along with DNA primers. He then heats the test tube, and the double helix separates into two strands. The process takes about 5 minutes and will result in two helices with the desired gene. -
CRISPr/CAS 9 Identified
CRISPR (Clustered Regularly Interspaced Short Paindromic Repeats) was first described by Yoshizumi Ishino in 1987 when he cloned part of a CRISPR together with the iap gene on accident. He earlier noted that iap was closely related to E. coli. Doudna & Charpentier studied the Cas9 which is a 4 component system that has CRISPR RNA and tracRNA. pg -
The Innocence Project
The Innocence Project is a non-profit organization that is dedicated to exonerating wrongfully convicted people using DNA testing and tries to reform the criminal justice system to prevent it from happening again. It was founded by Barry Scheck and Peter Neufeld. -
Dolly the Sheep
Dolly the Sheep was a cloned mammal from a somatic cell by means of nuclear transfer. Keith Campbell and Ian Wilmut were the ones who successfully cloned Dolly. The cell nucleus is transferred to an unfertilized egg cell that had its nucleus removed. Dolly lived until 02/14/2003 and was a huge scientific breakthrough. -
Sahelanthropus tchadensis fossil
This fossil was discovered in 2001 and is one of the earliest known species of our kind. It is theorized that it lived between 6-7 million years ago. It walked up-right, had canine teeth, a spinal cord similar to humans, and had a small brain. There were cranial fossils discovered in Chad, and others in different parts of Africa. humanorigins -
Human Genome
NHGRI and DOE announced their success in completing the Human Genome Project. The sequencing finds out the order of the base pairs in a DNA segment. HGP used BAC-based method to use clones to contain the genome. The BAC clone is mapped to see where the DNA comes from in the genome. Genome.gov -
Richard Bible execution
Flagstaff murderer Richard Bible was executed in June of 1988. This was the first use of DNA technology to convict someone. He was sentenced to death 23 years after the murder. The prosecutors were able to have DNA analysis done of Bible's blood to compare to blood found on the victim's shirt.
