Cell and Molecular Biology The Origin of Life

Cell and Molecular Biology The Origin of Life Behrouz Mahmoudi www. soran. edu. iq 1

Aristotle (384 – 322 BC) • Proposed theory of spontaneous generation • Also called abiogenesis • Idea that living things can arise from nonliving matter • Idea lasted almost 2000 years www. soran. edu. iq 2

Proposed Life-Generating Environments • Reducing Atmosphere + Lightning (methane hydrogen, ammonia, water) Urey and Miller experiment. • Hydrothermal Vents (hydrogen sulfide + carbon dioxide + heat in the deep ocean) • Primitive Clays Crystal structures in clays which could spontaneously catalyze the formation of certain prebiotic polymers. • Bubble theory • Exobiology Life came here from elsewhere www. soran. edu. iq 3

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Micelle www. soran. edu. iq 5

Biologists have formulated a list of characteristics by which we can recognize living things üCellular Organization üReproduction üMetabolism (Obtain and Use Energy) üHomeostasis üHeredity üResponsiveness Information processing üGrowth and Development üAdapt Through Evolution www. soran. edu. iq 6

Cell theory. a) Life exists only in cells b) The cell is the smallest unit of life. c) The continuity of life has a ellular basis. www. soran. edu. iq 7

Unicellular Organisms Multicellular Organisms üEntire organism is made up of one single cell üThe organism is made up of many cells üBacteria and protists www. soran. edu. iq üCells have specialized functions within the organism 8

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell www. soran. edu. iq 9

Reproduction is the process of producing new organisms of the same type. Asexual Reproduction üA single parent organism reproducing by itself Sexual Reproduction üTwo different parent organisms contribute genetic information üInvolves the combination of male and female sex cells www. soran. edu. iq 10

Asexual www. soran. edu. iq 11

Sexual: a new genetic combination www. soran. edu. iq 12

Living organisms need energy to grow, develop, repair damage, and reproduce www. soran. edu. iq 13

Anaboli sm The process of building up complex substances from simpler substances ü Building up cells and cellular components ü Photosynthesis www. soran. edu. iq 14

Catabolis The processm of breaking down complex substances into simpler substances to release energy ü Digestion ü Cellular Respiration www. soran. edu. iq 15

Metabolis The total ofm all chemical reactions in an organism ü Anabolism + Catabolism = Metabolism www. soran. edu. iq 16

A stable state of conditions in the body that are necessary for life üBody temperature üBlood volume üp. H balance üWater balance www. soran. edu. iq 17

Genes carry hereditary information Genes are composed of DNA Heredity is the reason children resemble their parents Mutations change DNA code and can be passed from generation to generation www. soran. edu. iq 18

Organisms react to stimuli: üLight An example is a plant’s leaves and stems growing toward light üTemperature üOdor üSound üGravity üHeat üWater üPressure www. soran. edu. iq 19