1875/1882 - Cellular Biology
1875: He contributed to plant cell biology by discovering the discrete stages of karyokinesis and cytokinesis in algae and higher plants, describing cytoplasmic streaming in different systems, and reporting on the growth of the pollen tube into the embryo sac and guidance of the tube by synergides.
1882: Walther Flemming was one of the first to devote his time to cytology, the study of chromosomes. Cell division had been described as early as 1842 by Carl Nageli, who thought it was an anomalous event. Flemming was the first to detail the chromosomal movements in the process of mitosis.
- Oswald Avery and his colleagues identified the molecule that transformed the R strain of bacteria into the S strain
- He isolated different molecules from killed S cells which he then exposed live R cells to
- This exposure transformed them into S cells
- Conclusion: S cell death releases DNA and the R bacteria incorporated it into their cells, changing them into S cells
- S strain = deadly infection of S pneumococci, R strain = non-virulent R pneumococci
- Proved that DNA (and not proteins) is the substance that is responsible for the transfer of genetic material
- Alexander Fleming accidentally revolutionized medicine by discovering the world's first antibiotic
- He had left on vacation and when he returned he noticed that one of his agar plates was contaminated with a fungus
- The bacteria surrounding the fungus had been completely destroyed
- He then grew and tested the fungus which became penicillin
- German scientist Theodor Boveri and the American Walter Sutton, working independently, suggested that chromosomes could be shown to bear the material of heredity.
- The process of "reduction division" (later called meiosis), which gives rise to reproductive germ cells, or gametes.
- In meiosis, the number of chromosomes is reduced by half in sperm and egg cells, with the original number restored in the zygote, or fertilized egg, during reproduction.
- Sutton suggested that "the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reduction division...may constitute the physical basis of the Mendelian law of heredity."
The botanist discovered chloroplasts as he was studying Andreas Schimper's work with photosynthetic organisms. Mereschkowsky was also the first scientist to propose the theory of symbiogenesis, the process by which larger, more complex cells evolve from their relationship with less complex cells.
- Katsusaburo Yamagiwa and Koichi Ichakawa induce cancer in rabbits by applying coal tar to their skin, providing experimental proof that chemicals can cause cancer
- This led to discovering that coal tar, asbestos, and tobacco are causes of cancer
- Researchers discovered a series of genes called hox genes that set the identity of insect bodies (eg: legs, antennae, wings) from head to tail
- Mutations to hox genes can put an entire leg where an antenna should sprout out or produce other grotesque transformations
This is significant to biology because it furthered genetic mutations and allowed scientists to create many cross genes such as the Grapple and Seedless watermelons.
- Louis Pasteur introduced aerobic & anaerobic cells
- Hypothesis: Microbes come from cells of organisms on dust particles in the air; not the air it self.
The theory of biogenisis
pasteur's S-shaped flask kept microbes from entering.
proved microbes only come from other microbes (life from life) - biogenesis.
- Jan Ingenhousz discovered that, in the presence of light, plants give off bubbles from their green parts while in the shade the bubbles eventually stop
- He identified the gas as oxygen
- He also discovered that in the dark plants give off carbon dioxide
- This demonstrated that some of the mass of plants comes from the air, and not only the soil
R. H. Whittaker proposed the five kingdom classification system
All living things are a member of the monera, protista, fungi, plantae, or animalia kingdoms
- the first thoroughly documented blood transfusion was performed.
- It was administered by the French physician Jean-Baptiste Denys, the famed physician of King Louis XIV (the Sun King).
- The transfusion which Denys performed was not from human to human, but from animal to human. Such transfusions are called xenotransfusions and they preceded human to human transfusions.
- Denys transfused sheep blood into a 15-year old boy. Apparently, the procedure was successful, and the young man recovered from his illness.
- It was probably due to the small amount of blood that was actually transfused that there was no major allergic reaction.
- However, some further attempts resulted in deaths, so in 1670 blood transfusion from animals to humans were banned.
- Rudolph Virchow states that all diseases are disturbances at the cellular level
- To treat disease we must understand its cause and to understand the cause we must understand the alterations that occur at the level of individual cells
Classification is important because it makes the study of such a wide variety of organisms easy, helps us uderstand the interrelationship among different groups of organisms, base for the development of other biological sciences such as biogeography.
- Edward Jenner develops a smallpox vaccine from cowpox pustules
- He observes that milkmaids are commonly immune to smallpox and hypothesizes that the milkmaids contract cowpox (a disease similar to smallpox but much less virulent) which then protects them from smallpox
- He tests this by injecting the pus from cowpox blisters on a milkmaid into an eight year old boy
- The boy becomes sick with cowpox but it passes and he is unable to contract smallpox after that - the vaccine was successful and the boy was immune
- He did further testing and this proved to be true
Taught people that blood transfusions are possible and important to biology as today we still use it to save many lifes
- Robert Hooke observes cork under a microscope and names the tiny chambers that he sees cells
- Publishes drawings of cells, fleas, and other small creatures in his book Micrographia
- Charles Darwin proposes a theory of evolution in his book On the Origin of Species saying that humans and apes share a common ancestor which sparks a heated debate
- Also states that the weak will die because they failed to adapt while the strong will adapt and pass on their favourable characteristics
Cells became the building blocks of every living thing and a huge part of biology as this is what we study and continue to learn about.
- Joseph Priestley produced the first evidence that gases participated in photosynthesis
- If a burning candle is placed in a sealed chamber, the candle goes out. If a mouse was placed in the chamber it would suffocate because combustion uses up all the oxygen in the air, which animals need to respirate
- He discovered that if a plant is placed in an atmosphere lacking oxygen, it soon replenishes the oxygen and a mouse can survive in this mixture
- In his experiment he placed a plant in water inside a sealed container with a mouse. The mouth survived because the plant converted the carbon dioxide into oxygen through photosynthesis
- Carl Linnaeus classified plants based on their sexual parts
- In his Systema Natura he systematically classified every species known to botany and zoology
- Species grouped into genera, then orders, then classes
- Species had a “double” like they do today
- Humans were homo sapiens - part of the animal kingdom
- Gregor Mendel published his findings of inheritance
- Passing of traits to the next generation - heredity
- Studied pea plant traits and cross-pollinated them
- Becomes known as the father of genetics
- Fritz Zernike creates the phase contrast microscope
- Now scientists were able to study biological lifeforms that were colourless or transparent which they were previously unable to study
- Francesco Redi tests the idea that flies spontaneously generate from rotting meat
- Observed that maggots (fly larvae) were only present in flasks open to flies
- Flasks that were closed had no maggots or flies
- Proved that life came from living materials and disproved spontaneous generation
- However this belief was not widely accepted as the flask with no flies also had no air, so critics argued that it was the lack of air that caused the lack of life
- When he later repeated the experiment and proved it, they agreed that it could be true for flies but nothing else
MIcroscopes are important in biology because it helps us learn more in depth about little organisms that are all around and to learn about things such as bacteria.
- Herman Kalckar observes glucose metabolism in microorganisms and animal tissue
- Discovered the role of ATP in energy metabolism
- Called father of bioenergetics
- Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeasts, insects, and many other tiny objects
- First person to describe bacteria
- Created curvatures providing a magnification of up to 270 diameters which made them the best lenses of the time
- Observed algae in lake water
- Discovered protozoa and other single-celled organisms
- First to study muscle fibers, spermatozoa, and blood flow in capillaries
- Called the father of biology because it revealed another world of organisms
1981: Reproduction (Stem Cells)
History of Biology Timeline
- Embryonic stem cells were independently first derived from mouse embryos by two groups
- Martin Evans and Matthew Kaufman revealed a new technique for culturing mouse embryos in the uterus to allow for an increase in cell number, allowing for the derivation of embryonic stem cells (ES cells) from these embryos
- Gail R. Martin showed that embryos could be cultured in vitro and that ES cells could be derived from these embryos
Charles Darwin’s boarded the Beagle that set sail from England
His job was to collect biological and geological specimens during the ship’s travels
He read a book proposing that the Earth was millions of years old which influenced his thinking
He observed fossils of marine life at high elevations in the Andes, unearthed giant fossil versions of smaller living mammals, and saw how earthquakes could lift rocks great distances very quickly
Noticed cliffs 45 feet above sea level which supported the theory that small changes happen on Earth very gradually
1974: Anthropology/Evolution of Humans
- Watson and Crick published a letter in the journal Nature suggesting a structure for DNA and hypothesizing how the molecule replicates, deduced from its structure
- DNA: a double helix structure held together by hydrogen bonds
- Wilkins and Franklin also published, in the same issue, evidence that supported the structure proposed by Watson and Crick
- In 1676 Leeuwenhoek discovered bacteria in water.
- The bacteria were at the limit of observation of his microscope – he estimated that it would take more than 10,000 of them to fill the volume of a small grain of sand. Such was the brilliance of his work that nobody else observed bacteria until another century had passed.
- Anthropologist Donald Johanson discovered an australopithecine skeleton that helped resolve the debate as to whether australopithecus africanus was bipedal (could walk upright on two legs)
- The fossil remains of “Lucy” are discovered and her anatomy provides convincing evidence that Australopithecus was bipedal (there are anatomical differences between quadrupeds and bipeds)
- A few years later Mary Leakey uncovered further evidence that they were bipedal when she discovered their footprints
DNA is important in biology because it is our genetic code, the stuff that orders your body to funtion propertly, DNA is thr root of all genetics which in summary make up yourself.
Evolution is important to biology because it shows the natural way of the world and nature.
1902 - Genetics/Inheritance
Theodor Schwann proposed that:
- All living matter is made up of cells
- The cell is the unit of structure, physiology, and organization in living things
- The cell retains a dual existence as an extinct entity and a building block in the construction of organisms
- Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation)
- James Lovelock and Lynn Margulis hypothesized that organisms interact with their inorganic surroundings on Earth to form a self-regulating, complex system that helps to maintain the conditions for life on the planet
- Suggests that organisms co-evolve with their environment
- They influence the abiotic environment and the abiotics environment influences them
- Archibald Garrod observes that the disease alkaptonuria is inherited according to Mendelian rules.
- It is suggested that chromosomes could be shown to bear material of heredity.
- Mendelian cocepts, as it turned out, had an excellent fit with facts about chromosomes.
- First clinical trial of stem cells receives FDA approval
- Limited phase I trial of a treatment for spinal cord injuries at first and later there were more trials
- Later that lear, scientists in Toronto reported the creation of stem cells from adult cells (iPS cells) in a safer manner than previous methods
- They removed the genes necessary to reprogram an adult cell into a stem cell after the reprogramming step is complete
- President Barack Obama repeals some of the restrictions on human embryonic stem cell research funds
- Walther Flemming described chromosome behaviour during mitosis
- Flemming proposed that all cell nuclei came from another predecessor nucleus
- Iguanodon is a genus of ornithopod dinosaur that existed roughly halfway between the first of the swift bipedal hypsilophodontids of the mid-Jurassic and the duck-billed dinosaurs of the late Cretaceous.
- English geologist Gideon Mantell, based on fossil specimens that are now assigned to Therosaurus and Mantellodon. Iguanodon was the second type of dinosaur formally named based on fossil specimens, after Megalosaurus. Together with Megalosaurus and Hylaeosaurus, it was one of the three genera originally used to define Dinosauria. The genus Iguanodon belongs to the larger group Iguanodontia, along with the duck-billed hadrosaurs. The taxonomy of this genus continues to be a topic of study as new species are named or long-standing ones reassigned to other genera.
- The Human Genome Project begins
- It’s an international effort to sequence the human genome and was completed in 2003
- There are approximately 3 billion nucleotides that make up human DNA and the goal was to determine the sequence of all of them as well as to identify all of the human genes
- In 1885 Roux removed a portion of the medullary plate of an embryonic chicken and maintained it in a warm saline solution for several days, establishing the principle of tissue culture which would later be taken up by Ross Granville Harrison and Paul Alfred Weiss.
Events that are connected?
Biology Discovery that could happen in the next 10 years?
- Godfrey Hardy and Wilhelm Weinberg prove mathematically that evolution will not occur in a population unless allelic frequencies are acted upon by forces that cause change (ie: natural selection)
- When these forces don’t exist, the allelic frequency doesn’t change and evolution doesn’t occur
- This genetic equilibrium is called the Hardy-Weinberg principle
- Publication of the Human Genome Project
- Found that:
- The number of genes turned out to be much smaller than once predicted
- There is a large amount of gene diversity and density
- Humans have many genes not found in invertebrates
- There are large amounts of repetitive DNA
Cells- 1665
Blood- 1667
Microscopy- 1674
Three most significant discoveries!
Aristotle – famous for the classification of living things
- Pavlov started from the idea that there are some things that a dog does not need to learn. For example, dogs don’t learn to salivate whenever they see food.
- He showed the existence of the unconditioned response by presenting a dog with a bowl of food and the measuring its salivary secretions.
- In his experiment, Pavlov used a bell as his neutral stimulus. Whenever he gave food to his dogs, he also rang a bell. After a number of repeats of this procedure, he tried the bell on its own. As you might expect, the bell on its own now caused an increase in salivation.
Cancer research – and its impact on patient care – has made some significant strides in just the last 10 years. For example, the availability and affordability of sequencing genetic information has improved greatly – meaning researchers and doctors are now better able to get information about a person’s risk for certain cancers as well as what drugs might work best for cancer patients.
If the cure of cancer came apparent to us in the next 10 years it could save millions of lives and create a new work force. Persona;;y it would affect me because both sides of my family have had cancer. My grandma and God Father both passed away from cancer. For there to be a cure they could have influenced my life a lot more and possibly still be with us today.
Ancient Greek philosopher, Aristotle, is often not considered when it comes to great biological discoveries but his work on the classification of living things was revolutionary at the time. Referred to as the 'Ladder of Life', Aristotle's classification system was still in use up until the 19th century – that's a long time. Aristotle was the first to person to recognise the relationships between species
- Theses topics all relate to each other due to the fact that, we as humans are always evolving and want to re-invent ourselves.
- At the time we did not know as much as we do toady about our bodies and how they function
- This pushes us as a evolving species to discover or create medicine, tools, machinery ect. to aid our every day needs
- Alexander Rich discovers Z-DNA: “left-handed” form of DNA that’s coiled in the shape of a left-handed screw
- Significance remained a mystery for many years
- Z-DNA is more likely to be present in regions of DNA with lots of cytosine and guanine as well as sodium
- Z-DNA is often associated with transcription
Antonie van Leeuwenhoek – known as the father of microbiology
Leeuwenhoek is well known for his contributions to microscopy, and how he applied this to the field of biology. He revolutionised a technique for creating powerful lenses, which some speculate were able to magnify up to 500 times. Leeuwenhoek used the microscopes to find out more about the living world
Robert Hooke – famous for discovering the cell
Hooke had an extraordinary ability to manipulate microscopes, and when applying this ability to looking closely at a thin slice of cork observed empty spaces contained with walls - terming them cells.