Origin Of Life Theories

Origin of life theories Creation myth or Cosmogonic myth is a supernatural mytho-religious story or explanation that describes the beginnings of humanity, earth, life, and the universe (cosmogony),[1] usually as a deliberate act by one or more deities. Abiogenesis is the study of how life on Earth emerged from inanimate organic and inorganic molecules. Scientific research theorizes that abiogenesis occurred sometime between 4.4 and 3.5 billion years ago. By 2.4 billion years ago the ratio of stable isotopes of carbon, iron and sulfur points to a biogenic origin of minerals and sediments and molecular biomarkers indicate photosynthesis. Biogenesis had accumulated so much evidential support, due to the work of Pasteur and others, that the alternative theory of spontaneous generation had been effectively disproven. Pasteur himself remarked, after a definitive finding in 1864, "Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment." The collapse of spontaneous generation, however, left a vacuum of scientific thought on the question of how life had first arisen. The Primordial Soup Theory Oparin argued that a "primeval soup" of organic molecules could be created in an oxygen-less atmosphere through the action of sunlight. These would combine in ever-more complex fashions until they formed coacervate droplets. These droplets would "grow" by fusion with other droplets, and "reproduce" through fission into daughter droplets, and so have a primitive metabolism in which those factors which promote "cell integrity" survive, those that do not become extinct. Many modern theories of the origin of life still take Oparin's ideas as a starting point. Around the same time J. B. S. Haldane also suggested that the earth's pre-biotic oceans – very different from their modern counterparts – would have formed a "hot dilute soup" in which organic compounds, the building blocks of life, could have formed. This idea was called biopoiesis or biopoesis, the process of living matter evolving from self-replicating but nonliving molecules. Evolution refers to changes in the inherited traits of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection The 7 Characteristics of Life: 1. Living Things are Composed of Cells: # Single-cell organisms have everything they need to be self-sufficient. # In multicellular organisms, specialization increases until some cells do only certain things. 2. Living Things Have Different Levels of Organization: • Both molecular and cellular organization. • Living things must be able to organize simple substances into complex ones. • Living things organize cells at several levels: • • • •

Tissue - a group of cells that perform a common function. Organ - a group of tissues that perform a common function. Organ system - a group of organs that perform a common function. Organism - any complete living thing.

3. Living Things Use Energy: • Living things take in energy and use it for maintenance and growth. 4. Living Things Respond To Their Environment: • Living things will make changes in response to a stimulus in their environment. • A behavior is a complex set of responses. 5. Living Things Grow: • Cell division - the orderly formation of new cells. • Cell enlargement - the increase in size of a cell. Cells grow to a certain size and then divide. • An organism gets larger as the number of its cells increases. 6. Living Things Reproduce: • Reproduction is not essential for the survival of individual organisms, but must occur for a species to survive. • All living things reproduce in one of the following ways: • Asexual repoduction - Producing offspring without the use of gametes. • Sexual reproduction - Producing offspring by the joining of sex cells. 7. Living Things Adapt To Their Environment: • Adaptations are traits giving an organism an advantage in a certain environment. • Variation of individuals is important for a healthy species. Comparison of plants and animals

Plants # Growth is Accretion # Reproduction are sexual and asexual # Has no locomotion or can not travel from one place to another. # Producer of its food. # makes use of Carbon dioxide released by the animals

Animals # Growth is intususception # Reproduction are sexual and asexual # has locomotion # Can not make its own food, eats its prey # makes use of Oxygen released by the plants

Comparison of Living and non living things Living things

Non-living things

# They breath # requires sunlight # has Reproduction # They grow # they have high brain function # made of cells

# Cannot breath # do not require sunlight # do not reproduce # do not grow # no brain # do not made up of cells