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Unformatted text preview: Topic 2 What is Life? Historical Perspectives Aristotle A student of Plato he developed the practice of logical thinking and guidelines for scientific thinking. The relationship of form and matter is an integral part of all things. Neither exists without the other. He had a hierarchical approach to classifying organisms. He espoused the concept of spontaneous generation. generation Historical Perspectives Redi Decided to test the concept of spontaneous generation The idea was that maggots arose spontaneously from decaying meat. Observed that flies had an affinity for rotten meat. Proposed that maggots came from flies and vice versa. Devised an experiment to test his hypothesis. Historical Perspectives Pasteur Discovered asymmetry in molecules (D,L). Father of microbiology for his work on fermentation and bacterial growth. Disproved the theory of spontaneous generation using his "swan necked flasks". Developed "Pasteurization" Contributed to the concept of "vaccination". Historical Perspectives Creationism A supreme being has created the universe. The time frame for creation is either literal or symbolic. Scopes monkey trial in 1925. 1925 The concept of evolution is still not accepted in many cultures. Does George Bush believe in evolution? Historical Perspectives Panspermia Life on earth originated from an extraterrestrial source. source Were we visited by aliens. Roswell, NM? aliens What about the evidence from asteroids and mars rocks? rocks "Is anybody out there".....Pink Floyd there"..... Studying Life Holism Vitalism...that there is a "vital force". Vitalism "gestalt" concept....the whole is greater than the sum of its parts. There is still a "wholistic approach" to thinking and studying biology and organisms. Physics......string theory Sociology/psychology...lack of real free will Ecology.....ecosystems, biosphere Studying Life Reductionism De ve lo p s a s a th e o ry c o inc id e nt with th e ris e o f Studying Life Emergent Properties Knowing the components does not necessarily provide a prediction of properties. properties Occurs at all levels of biological organization. The toothpick versus pasta conundrum. Reductionism and the analysis of life Alpha and Beta D-glucose Enzyme stereospecificity Properties associated with assembly Properties associated with interactions Hydrogen bonds Hydrophilicity vs. lipophilicity Studying Life Emergent Properties Rotation around the #1 carbon determines whether the OH is above or below the ring Studying Life Emergent Properties Depending on whether the 1,4 glycosidic linkage is from the alpha or beta configuration, the product is either starch or cellulose. Properties of Life Definition versus description Ho w d o e s o ne d e fine life . Diffe re nt c ulture s h a ve d iffe re nt d e finitio ns . De fining life is a t th e ro o t o f th e d e b a te o n a b o rtio n . We c a n o nly d e s c rib e life . P ro p e rtie s o f Life o r Ho w Do We De fine Life ? Biological Order The association of macromolecules to form the various structures such as membranes, organelles, cell walls, etc. Anabolism (metabolic building), Catabolism (metabolic breaking down) i.e.. respiration is catabolic Growth of cell size and number...tissues to organisms We maintain body temperature, blood pH etc.....maintaining the internal environment of the organism Energy Utilization (metabolism) Growth and Development Homeostasis P ro p e rtie s o f Life o r Ho w Do We De fine Life ? Response to the Environment Reproduction We put on a sweater when it is cool....response to external factors life begets life...the cell theory.....cells beget cells Sex is not for reproduction it is to maintain the diversity in the population so that the species has the capability to change in response to the environment Evolutionary Adaptation The Cell Theory Hooke (1635-1703) One of the most outstanding scientists of 17 century Not the inventor of the microscope (Galileo invented compound microscope) but first to use one to look at biological materials and to coin the term cell. cell Was the most important in studying and documenting a wide variety of organisms Worked on perfecting the microscope
th Van Leeuwenhoek (1632-1723) The Cell Theory Ma tth ia s S c h le id e n (1 8 0 4 1 8 8 1 ) n A botanist Recognized a role for the nucleus in cell division Early to accept Darwin's theory of evolution A zoologist and physiologist Considered the father of modern histology Defined the cell as basic unit of animal structure Many other accomplishments Schwann cells of nerves named after him T h e o d o r S c h wa nn (1 8 1 0 1 8 8 2 ) nn Principle Concepts of Cell Theory All living m a te ria l is c o nta ine d in c e lls . l T h e c e lls o f th e o rg a nis m a re a ll ind ivid ua l a nd l o f th e s a m e ra nk. nk T h e tis s ue c e ll is m o rp h o lo g ic a lly a nd p h y s io lo g ic a lly a n e le m e nta ry ind ivid ua l, th e unit o f s truc ture a nd func tio n . T h e o rg a nis m is a n a g g re g a te o f c e lls o r b uild ing b lo c ks . T h e func tio ning o f th e o rg a nis m is th e to ta lity o f th e num e ro us a c tio ns p e rfo rm e d b y m a ny kind s o f c e lls wo rking to g e th e r. r The Organismal Theory Originates from the many plasmodesmata found in plants Also originates from the existence of coenocytic (multinucleated) organisms The development of form in plants is a result of gradients. That there is a single protoplasmic mass that differentiates that can be apportioned into cells Unicellular protozoa versus man Consider the cellular slime molds such as Dictyostelium ...
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- Spring '08