EXPLORING LIFE Introduction and Origin.pptx

Introduction and Origin of Life

1. EXPLORING LIFE UNIT II

2. Every day, you and other organisms around you experience events that may cause you to change, adapt, and survive in your environment. Although you may be different from other organisms in the characteristics and in the roles you play in your environment, you are all interrelated.

3. No organism, not even a human like you, can exist on its own. All organisms depend on each other in order to survive . They are bound to each other in their forms, structures, functions, and synergizing contributions to their environment.

4. Looking at Life: An Introduction to Life Science MODULE 4

5. In this module, you will be able to Identify organisms and the conditions that enable them to exist (enrichment) Explain the evolution of life based on emerging pieces of evidence; Describe classic experiments that model conditions which may have enabled the first life-forms to evolve

6. Describe the unifying themes in the study of life; and Show the connections among living things and how they interact with each other and with their environment.

7. Life and Its remarkable Beginnings MODULE 4

8. PALEONTOLOGISTS are scientists who collect, identify, and study pieces of evidence about earlier life-forms and try to determine how these have evolved into the organisms of today. These pieces of evidence are among the fossils of organisms that existed about billions of years ago

9. A fossil is a remnant or trace of a plant, animal, or another organism that may have been replaced by rock material or left imprinted on a sedimentary rock deposited in riverbeds or on the ocean floor.

10. Some fossils are very small and can be seen only with the aid of a microscope. These are called MICROFOSSILS. The fossils that are considered the oldest on Earth are the STROMATOLITES. These are layers of sheet like sedimentary rocks that were created by layers upon layers of cyanobacteria, single celled photosynthetic microbes.

11. The pieces of evidence collected by paleontologists reveal the remarkable relationship between the diversity of organisms from the earlier life-forms to the present.

12. Scientific research shows that earliest life-forms had gone through evolution , or the gradual change and development of a species or a group of organisms that lead to more advanced form

13. Characteristics of Life

14. (1) the use of chemical energy to help organisms perform activities and carry out chemical reactions (energy processing); (2) the ability of individuals to adapt to their environment (evolutionary adaptation);

15. (3) the consistent growth and development controlled by the inherited gene; (4) the systematic and highly ordered structure of organisms; (5) the ability of organisms to control their internal environment (regulation);

16. (6) the ability of organisms to respond to environmental stimuli; and (7) the ability of every organism to reproduce its own kind

17. Hierarchy of the Biological Organization

18. Unifying Themes of Life GENETICS, EVOLUTION, AND BIOCHEMISTRY.

19. GENETICS is the branch of biology that studies heredity and variation. Genetics shows how the characteristics of the parents are transmitted to their offspring through the reproductive process.

20. Genetics is a unifying theme in biology because it allows humans to understand the complexities of the existence of life. The genetic variation of organisms is also the reason for the natural diversity between and across species.

21. The biological or genetic information and characteristics of an organism are contained in their genes, chemically known as genetic makeup or deoxyribonucleic acid (DNA).

22. Experiments on the Evolution of Life

23. THE THEORY OF SPONTANEOUS GENERATION Spontaneous generation states that vital forces or organic matter can create organisms from inanimate objects. Aristotle claimed that some classes of organisms generate spontaneously.

24. THE THEORY OF SPONTANEOUS GENERATION The appearance of maggots in meat that was left in the open area was thought to be an example of spontaneous generation

25. Redi’s Experiment

26. REDI’S EXPERIMENT Among the scientists who challenged the theory of spontaneous generation was Francesco Redi (1626–1697), an Italian scientist. In 1668, Redi designed a scientific experiment to demonstrate that maggots do not just appear spontaneously but are produced from the eggs of flies.

27. REDI’S EXPERIMENT For his experiment, Redi used two groups of jars. Three jars were used in each group. For the first group, Redi placed an unknown object in jar 1, then a dead fish in jar 2, and a chunk of red meat in jar 3. For the second group, Redi placed the same objects in the three jars. However, he left these uncovered.

28. REDI’S EXPERIMENT A couple of days later, Redi noticed maggots on the objects in all the uncovered jars while there were none on the objects in the covered jars, although maggots were present on the cheesecloth of the covered jars. Through this experiment, Redi was able to prove that organisms do not just come to life spontaneously.

29. Needham’s Test

30. NEEDHAM’S EXPERIMENT In 1750, John Turberville Needham (1713–1781), an English biologist attempted to test the relevance of Redi’s experiment and prove that spontaneous generation can occur under the right conditions. At that time, it was believed that heat could kill even the tiniest of organisms.

31. NEEDHAM’S EXPERIMENT Based on this, Needham conducted an experiment wherein he put some chicken broth in an open container, let it cool, and then covered the container and kept it at room temperature. Needham claimed that, when the broth was boiled, all the organisms in it had died from the heat.

32. NEEDHAM’S EXPERIMENT Days later, when Needham examined the broth, he noticed that a thick solution had formed on the broth and concluded that this was made up of microorganisms that had been generated spontaneously.

33. NEEDHAM’S EXPERIMENT

34. Spallanzani’s Experiments

35. SPALLANZANI’S EXPERIMENT Lazzaro Spallanzani (1729–1799) was an Italian scholar who sought to verify Needham’s test in 1767. Spallanzani believed that Needham had not heated the broth enough to kill the organisms in it.

36. SPALLANZANI’S EXPERIMENT He then repeated Needham’s experiment by boiling equal amounts of chicken broth in two containers, with one container sealed and the other left open.

37. SPALLANZANI’S EXPERIMENT After a few days, Spallanzani observed that the container that had been left open was teeming with microorganisms while the sealed container remained free of microbial growth.

38. SPALLANZANI’S EXPERIMENT

39. Pasteur’s Test

40. PASTEUR’S TEST Louis Pasteur (1822–1895) opposed the concept of spontaneous generation. He believed that microorganisms that decay or spoil materials are present in the air or might have been existing on the surface where decaying materials are found.

41. PASTEUR’S TEST Putrefaction or rotting of organic material is a result of the activities of microorganisms present either in air or in the container.

42. PASTEUR’S TEST If the food were treated to kill the microorganisms and make it sterile, then the food will be protected from rotting or putrefaction

43. PASTEUR’S TEST The process of heating was used by Pasteur to eliminate contaminants. Pasteur disproved spontaneous generation by conducting an experiment (shown in Figure 4.11 on the next page) where he used the process of pasteurization.

44. PASTEUR’S TEST Pasteur filled a swan-necked flask with a nutrient solution that he boiled and sterilized. After heating, the flask was cooled and the air was allowed to reenter, but the bend in the neck prevented particulate matter such as microorganisms from entering and mixing with the nutrient solution that would eventually cause rotting.

45. PASTEUR’S TEST His experiment showed that in the heated flask, organisms did not proliferate. Later on, Pasteur broke the flask and the flask slowly became filled with microorganisms. The work of Pasteur proved that the hypothesis of spontaneous generation is incorrect

46. PASTEUR’S TEST The controversy about spontaneous generation was put to an end because of Pasteur’s experiment. Pasteur’s experiment gave rise to the study of microbiology. Later on, the process introduced by Pasteur was developed and carried out as a basic procedure in both research and food industry.

47. PASTEUR’S TEST