Historians accept that Hippocrates was born around the year 460 BC on the Greek island of Kos (Cos), and became a famous physician and teacher of medicine. Other biographical information, however, is likely to be untrue ( see Legends ).  Soranus of Ephesus, a 2nd-century Greek gynecologist,  was Hippocrates' first biographer and is the source of most information on Hippocrates' person. Information about Hippocrates can also be found in the writings of Aristotle, which date from the 4th century BC, in the Suda of the 10th century AD, and in the works of John Tzetzes, which date from the 12th century AD. 
Soranus wrote that Hippocrates' father was Heraclides, a physician; his mother was Praxitela, daughter of Tizane. The two sons of Hippocrates, Thessalus and Draco, and his son-in-law, Polybus, were his students. According to Galen, a later physician, Polybus was Hippocrates' true successor, while Thessalus and Draco each had a son named Hippocrates. 
Soranus said that Hippocrates learned medicine from his father and grandfather, and studied other subjects with Democritus and Gorgias. Hippocrates was probably trained at the asklepieion of Kos, and took lessons from the Thracian physician Herodicus of Selymbria. The only contemporaneous mention of Hippocrates is in Plato's dialogue Protagoras , where Plato describes Hippocrates as "Hippocrates of Kos, the Asclepiad".  Hippocrates taught and practiced medicine throughout his life, traveling at least as far as Thessaly, Thrace, and the Sea of Marmara.  He probably died in Larissa at the age of 83 or 90, though some accounts say he lived to be well over 100; several different accounts of his death exist. 
Aristotle was born in Stageira, Chalcidice, in 384 BC, about 55 km east of modern-day Thessaloniki.  His father Nicomachus was the personal physician to King Amyntas of Macedon. Aristotle was trained and educated as a member of the aristocracy. At about the age of eighteen, he went to Athens to continue his education at Plato's Academy. Aristotle remained at the academy for nearly twenty years, not leaving until after Plato's death in 347 BC. He then traveled with Xenocrates to the court of his friend Hermias of Atarneus in Asia Minor. While in Asia, Aristotle traveled with Theophrastus to the island of Lesbos, where together they researched the botany and zoology of the island. Aristotle married Hermias's adoptive daughter (or niece) Pythias. She bore him a daughter, whom they named Pythias. Soon after Hermias' death, Aristotle was invited by Philip II of Macedon to become the tutor to his son Alexander the Great in 343 B.C. 
Early Islamic portrayal of Aristotle
Aristotle portrayed in the 1493 Nuremberg Chronicle as a 15th-century-A.D. scholar
Aristotle was appointed as the head of the royal academy of Macedon. During that time he gave lessons not only to Alexander, but also to two other future kings: Ptolemy and Cassander. In his Politics , Aristotle states that only one thing could justify monarchy, and that was if the virtue of the king and his family were greater than the virtue of the rest of the citizens put together. Tactfully, he included the young prince and his father in that category. Aristotle encouraged Alexander toward eastern conquest, and his attitude towards Persia was unabashedly ethnocentric. In one famous example, he counsels Alexander to be 'a leader to the Greeks and a despot to the barbarians, to look after the former as after friends and relatives, and to deal with the latter as with beasts or plants'.  Near the end of Alexander's life he began to suspect plots, and threatened Aristotle in letters. Aristotle had made no secret of his contempt for Alexander's pretense of divinity, and the king had executed Aristotle's grandnephew Callisthenes as a traitor. A widespread tradition in antiquity suspected Aristotle of playing a role in Alexander's death, but there is little evidence for this. 
By 335 BC he had returned to Athens, establishing his own school there known as the Lyceum. Aristotle conducted courses at the school for the next twelve years. While in Athens, his wife Pythias died and Aristotle became involved with Herpyllis of Stageira, who bore him a son whom he named after his father, Nicomachus. According to the Suda, he also had an eromenos, Palaephatus of Abydus. 
It is during this period in Athens from 335 B.C. to 323 B.C. when Aristotle is believed to have composed many of his works.  Aristotle wrote many dialogues, only fragments of which survived. The works that have survived are in treatise form and were not, for the most part, intended for widespread publication, as they are generally thought to be lecture aids for his students. His most important treatises include Physics , Metaphysics , Nicomachean Ethics , Politics , De Anima (On the Soul) and Poetics .
Aristotle not only studied almost every subject possible at the time, but made significant contributions to most of them. In physical science, Aristotle studied anatomy, astronomy, economics, embryology, geography, geology, meteorology, physics and zoology. In philosophy, he wrote on aesthetics, ethics, government, metaphysics, politics, psychology, rhetoric and theology. He also studied education, foreign customs, literature and poetry. His combined works constitute a virtual encyclopedia of Greek knowledge. It has been suggested that Aristotle was probably the last person to know everything there was to be known in his own time. 
Upon Alexander's death, anti-Macedonian sentiment in Athens once again flared. Eurymedon the hierophant denounced Aristotle for not holding the gods in honor. Aristotle fled the city to his mother's family estate in Chalcis, explaining, "I will not allow the Athenians to sin twice against philosophy,"  a reference to Athens's prior trial and execution of Socrates. However, he died in Euboea of natural causes within the year (in 322 BC). Aristotle named chief executor his student Antipater and left a will in which he asked to be buried next to his wife. 
All the biographical information we have of him was provided by Diogenes Laërtius' Lives of the Philosophers , written four hundred years after Theophrastus' time, though "there is no intrinsic improbability in most of what Diogenes records."  His given name was Tyrtamus (Greek: Τύρταμος), but he later became known by the nickname "Theophrastus", given to him, it is said, by Aristotle to indicate the grace of his conversation (ancient Greek: Θεός = God and φραστος = to phrase i.e divine expression). 
According to some sources, Theophrastus' father was named Messapus, and was married to a woman named Argiope and was the father of Cercyon—but, this is not certain.
After receiving his first introduction to philosophy in Lesbos from one Leucippus or Alcippus, he proceeded to Athens, and became a member of the Platonist circle.  After Plato's death he attached himself to Aristotle, and in all probability accompanied him to Stagira. The intimate friendship of Theophrastus with Callisthenes,  the fellow-pupil of Alexander the Great, the mention made in his will of an estate belonging to him at Stagira,  and the repeated notices of the town and its museum in the nine books of his Enquiry into plants and his six books of Causes of Plants point to this conclusion.
Aristotle in his will made him guardian of his children, including Nicomachus with whom he was close.  Aristotle likewise bequeathed to him his library and the originals of his works,  and designated him as his successor at the Lyceum on his own removal to Chalcis.  Eudemus of Rhodes also had some claims to this position, and Aristoxenus is said to have resented Aristotle's choice.
Theophrastus presided over the Peripatetic school for thirty-five years,  and died at the age of eighty-five according to Diogenes.  He is said to have remarked "we die just when we are beginning to live". 
Under his guidance the school flourished greatly— there were at one period more than 2000 students, Diogenes affirms,  and at his death, according to the terms of his will preserved by Diogenes, he bequeathed to it his garden with house and colonnades as a permanent seat of instruction. The comic poet Menander was among his pupils.  His popularity was shown in the regard paid to him by Philip, Cassander and Ptolemy, and by the complete failure of a charge of impiety brought against him.  He was honoured with a public funeral, and "the whole population of Athens, honouring him greatly, followed him to the grave."  He was succeeded as head of the Lyceum by Strato of Lampsacus.
Aelius Galenus or Claudius Galenus (AD 129 – 200/217), better known as Galen of Pergamum (Greek: Γαληνός, Galēnos ), was a prominent Roman physician and philosopher of Greek origin,  and probably the most accomplished medical researcher of the Roman period. His theories dominated and influenced Western medical science for well over a millennium. His account of medical anatomy was based on monkeys as human dissection was not permitted in his time, but it was unsurpassed until the printed description and illustrations of human dissections by Andreas Vesalius in 1543.  Galen's account of the activities of the heart, arteries and veins endured until William Harvey established that the blood circulates with the heart acting as a pump in 1628.  In the 19th century, student physicians would still read Galen to learn some concepts. Galen developed many nerve ligation experiments that supported the theory, which is still believed today, that the brain controls all the motions of the muscles by means of the cranial and peripheral nervous systems.  Galen wrote a small work called "That the Best Physician is also a Philosopher"  , and he saw himself as being both, which meant grounding medical practice in theoretically sound knowledge or "philosophy" as it was called in his time. Galen was very interested in the dispute between Rationalist and Empiricist medical sects,  and his use of direct observation, dissection and vivisection in medical training and as a way to ground medical practice can be understood as considering both of those perspectives and constructing a more complex and nuanced middle ground that avoided problems with each position. 
Vesalius was born in Brussels, into a family long associated with the medical care of the imperial dynasty; his father was the pharmacist for Roman Emperor Charles V. From an early age, Vesalius showed an inclination to follow in the family tradition through his dissection of dead birds and mice. He studied at the University of Leuven from 1530 until 1533, when he began his studies at the University of Paris under Jacobus Sylvius and Johann Guinther. At the outbreak of the war between France and the Holy Roman Empire in 1536, Vesalius returned home to complete his studies at the University of Leuven, where he received his medical degree in 1537.
In the autumn of 1537, Vesalius enrolled in the medical school of the University of Padua, and received his doctorate of medicine shortly thereafter. Upon his graduation, he was immediately offered the chair of Surgery and Anatomy ( explicator chirurgiae ) at Padua, where he began giving public lectures. His innovative lectures and course plans were unique for two reasons. First, he performed his own dissections rather than reading aloud while a demonstrator did the dissection and second, because he used drawings to aid his teaching. These drawings became an integral part in his teaching, and later in his published works.
Soon thereafter, Vesalius became interested in the validity of Galen's findings, and began his study on human anatomy and his major work, De humani corporis fabrica . In 1539, a Paduan judge became interested in Vesalius' work, and made bodies of executed criminals available for dissection. His collection of detailed anatomical diagrams grew, many of which were produced by commissioned artists in the area and were of better quality than previous diagrams. His diagrams became known as the first accurate set of diagrams to be produced.
In 1540, Vesalius went to Bologna where he presented his anatomical findings and criticized Galen for his methods of studying the human anatomy. Between 1539 and 1542, Vesalius compiled his findings, a majority of which were in contradiction to Galen's work, in his masterpiece, De fabrica , and employed talented artists to provide illustrations of the human body, an important feature of his book.
Soon after the publication of De fabrica , Vesalius was invited to become the imperial physician to the court of Emperor Charles V, where over the next twelve years, he traveled with the court, treated injuries from battles and tournaments, and performed surgeries as well as postmortems. He also wrote private letters that addressed specific medical questions. After the abdication of Charles, he continued working for the court under Charles's son, Philip II, who rewarded Vesalius with a life pension.
During the late twentieth century, the American artist, Jacob Lawrence accomplished his Vesalius Suite based on the anatomical drawings of Andreas Vesalius.
On a journey back from Jerusalem in 1564, Vesalius died in a shipwreck off the coast of Greece, near Zante.
Leonardo Da Vinci
Leonardo di ser Piero da Vinci ( pronunciation (help·info), April 15, 1452 – May 2, 1519) was an Italian polymath, scientist, mathematician, engineer, inventor, anatomist, painter, sculptor, architect, botanist, musician and writer. Leonardo has often been described as the archetype of the renaissance man, a man whose unquenchable curiosity was equaled only by his powers of invention.  He is widely considered to be one of the greatest painters of all time and perhaps the most diversely talented person ever to have lived.  Helen Gardner says "The scope and depth of his interests were without precedent...His mind and personality seem to us superhuman, the man himself mysterious and remote". 
Born as the illegitimate son of a notary, Piero da Vinci, and a peasant woman, Caterina, at Vinci in the region of Florence, Leonardo was educated in the studio of the renowned Florentine painter, Verrocchio. Much of his earlier working life was spent in the service of Ludovico il Moro in Milan. He later worked in Rome, Bologna and Venice and spent his last years in France, at the home awarded him by Francis I.
Leonardo was and is renowned  primarily as a painter. Two of his works, the Mona Lisa and The Last Supper , are the most famous, most reproduced and most parodied portrait and religious painting of all time, respectively, their fame approached only by Michelangelo's Creation of Adam .  Leonardo's drawing of the Vitruvian Man is also regarded as a cultural icon,  being reproduced on everything from the Euro to text books to t-shirts. Perhaps fifteen of his paintings survive, the small number due to his constant, and frequently disastrous, experimentation with new techniques, and his chronic procrastination. [nb 2] Nevertheless, these few works, together with his notebooks, which contain drawings, scientific diagrams, and his thoughts on the nature of painting, comprise a contribution to later generations of artists only rivalled by that of his contemporary, Michelangelo.
Leonardo is revered  for his technological ingenuity. He conceptualised a helicopter, a tank, concentrated solar power, a calculator, the double hull and outlined a rudimentary theory of plate tectonics.  Relatively few of his designs were constructed or were even feasible during his lifetime, [nb 3] but some of his smaller inventions, such as an automated bobbin winder and a machine for testing the tensile strength of wire, entered the world of manufacturing unheralded. [nb 4] As a scientist, he greatly advanced the state of knowledge in the fields of anatomy, civil engineering, optics, and hydrodynamics. 
Anton Van Leeuwenhoek
Anton Philips van Leeuwenhoek (in Dutch also Anthonie, Antoni or Theunis, in English Antony or Anton)  (born on October 24, 1632 – baptized on November 4, and buried on August 30, 1723) was a Dutch tradesman and scientist from Delft, the Netherlands. He is commonly known as "the Father of Microbiology", and considered to be the first microbiologist. He is best known for his work on the improvement of the microscope and for his contributions towards the establishment of microbiology. Using his handcrafted microscopes he was the first to observe and describe single celled organisms, which he originally referred to as animalcules , and which we now refer to as microorganisms. He was also the first to record microscopic observations of muscle fibers, bacteria, spermatozoa and blood flow in capillaries (small blood vessels). Van Leeuwenhoek never wrote a book, just letters.
Charles Robert Darwin FRS (12 February 1809 – 19 April 1882) was an English naturalist [I] who realised and presented compelling evidence that all species of life have evolved over time from common ancestors, through the process he called natural selection.  The fact that evolution occurs became accepted by the scientific community and much of the general public in his lifetime, while his theory of natural selection came to be widely seen as the primary explanation of the process of evolution in the 1930s,  and now forms the basis of modern evolutionary theory. In modified form, Darwin’s scientific discovery is the unifying theory of the life sciences, providing logical explanation for the diversity of life. 
At Edinburgh University Darwin neglected medical studies to investigate marine invertebrates, then the University of Cambridge encouraged a passion for natural science.  His five-year voyage on HMS Beagle established him as an eminent geologist whose observations and theories supported Charles Lyell’s uniformitarian ideas, and publication of his journal of the voyage made him famous as a popular author. Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin investigated the transmutation of species and conceived his theory of natural selection in 1838.  Although he discussed his ideas with several naturalists, he needed time for extensive research and his geological work had priority.  He was writing up his theory in 1858 when Alfred Russel Wallace sent him an essay which described the same idea, prompting immediate joint publication of both of their theories. 
His 1859 book On the Origin of Species established evolutionary descent with modification as the dominant scientific explanation of diversification in nature.  He examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex , followed by The Expression of the Emotions in Man and Animals . His research on plants was published in a series of books, and in his final book, he examined earthworms and their effect on soil. 
In recognition of Darwin’s pre-eminence, he was one of only five 19th-century UK non-royal personages to be honoured by a state funeral,  and was buried in Westminster Abbey, close to John Herschel and Isaac Newton. 
Humans, Animals, Plants
Sustainable Development Development that "meets the needs of the present without compromising the ability of future generations to meet their own needs."
Interest & Appreciation
The cell is the structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building brick of life.  Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. (Humans have an estimated 100 trillion or 10 14 cells; a typical cell size is 10 µm; a typical cell mass is 1 nanogram.) The largest known cell is an unfertilized ostrich egg cell. 
In 1835 before the final cell theory was developed, a Czech Jan Evangelista Purkyně observed small "granules" while looking at the plant tissue through a microscope. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells. All cells come from preexisting cells. Vital functions of an organism occur within cells, and all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells. 
The word cell comes from the Latin cellula , meaning, a small room. The descriptive name for the smallest living biological structure was chosen by Robert Hooke in a book he published in 1665 when he compared the cork cells he saw through his microscope to the small rooms monks lived in.
Parts of a Cell
A cell is the smallest part of any living thing. There are many parts of a cell. Each part of a cell completes a certain function for the cell. All cells include the following parts:
Cell Membrane - forms the outer boundary of the cell and allows only certain materials to move into or out of the cell
Cytoplasm - a gel-like material inside the cell; it contains water and nutrients for the cell
Nucleus - directs the activity of a cell; it contains chromosomes with the DNA
Nuclear Membrane - separates the nucleus from the cytoplasm
Endoplasmic Reticulum - moves materials around in the cell
Ribosomes - make protein for the cell
Golgi Bodies - are used for packaging and secreting of energy
Mitochondria - break down food and release energy to the cell
Lysosomes - are chemicals used to digest waste
Vacuoles - are storage areas for the cell
Some organelles are found only in Plant cells. These organelles are:
Cell Wall - provides structure to the plant cell
Chloroplasts - contain chlorophyll that is make food for the plant cell
Animal Cell Plant Cell
Cell motility describes the methods that single-celled organisms use to both move in their environments and move things internal to the cell. Different types of cells use a variety of strategies to seek food, produce energy, avoid death and fulfill roles. In multicellular organisms, cell motility enables single cells and groups of cells to migrate in the embryo to the appropriate locations in the body. Unfortunately, this same process critical to physical development becomes deadly when uncontrolled, leading to cancer and the metastasis of cancerous cells. Most cells in complex animals are stationary. However, cell motility may also be demonstrated in morphology: muscle cell contraction, nerve axon elongation, cell-surface protrusions, even the dividing of cells during mitosis. Inside cells, much more dynamism in cell motility is observed: cytosol streams, vesicle transport systems, and the separation of chromosomes and creation of RNA. Everything in a normal cell is carefully controlled. ATP fuels all cell movements, along with the action of proteins that convert ATP's energy. The cytoskeleton, a changeable system of fibers in the cytoplasm, supports the cell membrane and provides "tracks" for organelles and other elements to move through the cytosol. This system is constantly rearranging itself to suit new processes. This system is a secondary source of cell motility.
Irritability “ Mimosa pudica”
Cell irritability is the ability of living things to react to environment stimuli, such as light, temperature, pressure, tension, chemicals, and gravity.
Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter, for example to harvest energy in cellular respiration. Anabolism, on the other hand, uses energy to construct components of cells such as proteins and nucleic acids.
The chemical reactions of metabolism are organized into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes. Enzymes are crucial to metabolism because they allow organisms to drive desirable but thermodynamically unfavorable reactions by coupling them to favorable ones, and because they act as catalysts to allow these reactions to proceed quickly and efficiently. Enzymes also allow the regulation of metabolic pathways in response to changes in the cell's environment or signals from other cells.
The metabolism of an organism determines which substances it will find nutritious and which it will find poisonous. For example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals.  The speed of metabolism, the metabolic rate, also influences how much food an organism will require.
A striking feature of metabolism is the similarity of the basic metabolic pathways between even vastly different species. For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all organisms, being found in species as diverse as the unicellular bacteria Escherichia coli and huge multicellular organisms like elephants.  These striking similarities in metabolism are most likely the result of the high efficiency of these pathways, and of their early appearance in evolutionary history.
A zygote (or zygocyte ) (from Greek ζυγωτός zugōtos "joined" or "yoked", from ζυγοῦν zugoun "to join" or "to yoke")  is a term in Developmental biology used to describe the first stage of a new unique organism when it consists of just a single cell. The term is also used more loosely to refer to the group of cells formed by the first few cell divisions, although this is properly referred to as a blastomere. A zygote is usually produced by a fertilization event between two haploid cells - an ovum from a female and a sperm cell from a male - which combine to form the single diploid cell. Thus the zygote contains DNA originating from both mother and father and this provides all the genetic information necessary to form a new individual.
In mammal reproduction, after fertilization has taken place the zygote travels down the fallopian tube, while dividing to form more cells  without the zygote actually gaining in size. This cell division is mitotic, and is known as "cleavage".  All mammals go through the zygote stage of life. Zygotes will develop into an embryo, and then a fetus. A human zygote exists for about four days, and becomes a blastocyst on the fifth day. 
The term cell growth is used in the contexts of cell development and cell division (reproduction). When used in the context of cell division, it refers to growth of cell populations, where one cell (the "mother cell") grows and divides to produce two "daughter cells".