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Unifying Characteristics of Life

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Unifying Characteristics of Life

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  1. Unifying Characteristics of Life • Order - the smallest unit of life is the cell; all living things have complex organization • Regulation – • Metabolism—synthesis and break down of molecules, producing energy to power life processes. • Responsiveness— • Development—from simple to more complex organism • Reproduction/Heredity— • Evolution— populations change over time as they adapt

  2. Biological Organization 4. Cell: Fig 1.1 3. Organelle: A structure within a cell that performs a specific function 2. Molecule: 1.Atom: smallest unit of an element that still retains the element’s properties

  3. 7. Organ System: A group of body parts that carries out a particular function in an organism 6. Organ : 5. Tissue: A group of similar cells that carries out a particular func- tion in an organism

  4. 9. Population: 10. Community: all populations of all species occupying a specific area 8. Organism: individual composed of many coordinated organ systems

  5. 11. Ecosystem: 12. Biosphere: Those regions of the earth’s waters, crust and atmosphere in which organisms can exist.The global ecosystem

  6. Cells and Their DNA • The cell is the simplest structure that can perform all activities required for life • Cell Theory: • There are two major types of cells • Prokaryotic cells • Eukaryotic cells

  7. The prokaryotic cell is simple and contains no organelles Nucleus (contains DNA) • The eukaryotic cell Eukaryotic cell Prokaryotic cell DNA (no nucleus) Organelles Fig 1.3

  8. All cells use DNA as the chemical material of genes • Genes

  9. The Diversity of Life • The diversity of known life includes 1.7 million species • Estimates of the total diversity range from 5 million to over 30 million species

  10. The Unity and Diversity of Life EUKARYOTES Plants Animals Fungi Protists Bacteria Archaea: PROKARYOTES Universal Ancestor

  11. The Three Domains of Life • The three domains of life are: • Bacteria • Archaea • Eukarya: consists of four kingdoms: • Protista • Animalia • Plantae • Fungi

  12. Domain Archaea Domain Bacteria Domain Eukarya Kingdom Protista Kingdom Plantae Kingdom Animalia Kingdom Fungi Fig 1.5B

  13. Unity in the Diversity of Life • Underlying the diversity of life is a striking unity, especially at the lower levels of structure • Example: • Evolution accounts for this combination of unity and diversity

  14. EVOLUTION: BIOLOGY’S UNIFYING THEME • The history of life is a saga of a restless Earth billions of years old • Fossils document this history

  15. Life evolves Ancestral bear

  16. The Darwinian View of Life • The evolutionary view of life came into focus in 1859 when Charles Darwin published The Origin of Species

  17. Darwin’s book developed two main points • . • .

  18. Natural Selection • Darwin was struck by the diversity of animals on the Galápagos Islands • He thought of origin of new species and adaptation to the environment the as closely related processes

  19. Descent with modification • Fourteenspecies of Galápagos finches have beak shapes adapted to suit their environ-ments Cactus ground finch Medium ground finch Small tree finch Medium tree finch Woodpecker finch Large cactus ground finch Large ground finch Small ground finch Gray warbler finch Green warbler finch Large tree finch Vegetarian finch Mangrove finch Sharp-beaked ground finch Cactus-flower-eaters Bud-eater Seed-eaters Insect-eaters Tree finches Ground finches Warbler finches Common ancestor from South American mainland

  20. Darwin’s Conclusion • Darwin synthesized the concept of natural selection from two observations:

  21. Fact 1: Struggle for existence • Fact 2: Individual variation • Conclusion: • The product of natural selection is adaptation

  22. Fig 1.6B: Natural Selection

  23. The Evolution of Diversity • Different species have different traits. These arise from: • Mutations – • Evolution – heritable changes in the line of descent over time. Caused by: • Natural selection - adaptive traits tend to increase over time. It is the mechanism of evolution

  24. Observing Artificial Selection • Artificial selection is the selective breeding of domesticated plants and animal by humans Fig 13.2

  25. Observing Natural Selection • There are many examples of natural selection in action

  26. Darwin’s publication of The Origin of Species fueled an explosion in biological research • Evolution is one of biology’s best demonstrated, most comprehensive, and longest lasting theories • Evolution is the unifying theme of biology

  27. Chapter 2: Chemical Basis of Life

  28. BASIC CHEMISTRY • Organisms and all other things in the universe consist of matter • Matter • Matter is composed of chemical elements • There are 92 naturally occurring elements on Earth

  29. Atomic number Periodic table of the elements Element symbol Mass number

  30. 25 Elements are essential to life

  31. Elements • Elements can combine to form compounds • Compounds • Examples of Compounds: • Table salt (sodium chloride): NaCl • Water: H2O • Glucose: C6H12O6 • Is O2 gas a compound?

  32. Atom:smallest unit of matter that retains the properties of an element (a) Hydrogen atom (b) Carbon atom (c) Oxygen atom Proton Neutron Electron First shell Second shell Atomic nucleus Fig. 2.02

  33. Atomic Structure • The subatomic particles of an atom Electron Negativecharge Proton • Participates in chemical reactions  Positive charge  • Neutron  No charge Nucleus • Consists of neutrons and protons

  34. Elements • differ in the number of protons in their atoms • Atomic Number: • Mass number • sum of the number of protons and neutrons

  35. Chemical Properties of Atoms • Electrons • The number of electrons in the outermost shell determines the chemical properties of an atom

  36. Atoms of the four elements most abundant in life First electron shell: can hold 2 electrons Outermost electron shell: can hold 8 electrons Electron Hydrogen (H) Atomic number = 1 Carbon (C) Atomic number = 6 Nitrogen (N) Atomic number = 7 Oxygen (O) Atomic number = 8

  37. Chemical Bonding and Molecules • Chemical reactions: • Atoms give up, acquire, or share electrons in order to complete their outer shells • Result: • 2 types of molecular bonding: • Ionic Bonds • Covalent bonds

  38. Ionic Bonds • When an atom loses or gains electrons, it becomes electrically charged = ion • Ionic bonds Sodium atom Chlorine atom Complete outer shells Na Cl Fig 2.7A Sodium chloride (NaCl)

  39. Atoms: electrically neutral Ions: Electrically charged (a) Hydrogen atom (H) (b) Hydrogen ion (H+) 1 electron No electron 1 proton 1 proton No electrical charge (c) Sodium atom (Na) (d) Sodium ion (Na+) 11 electrons 10 electrons 11 protons 11 protons No electrical charge

  40. Covalent Bonds Table 2.8 • A covalent bond forms when

  41. Covalent bonding in water Water molecule (H2O) Oxygen atom with unfilled shell Full shell with 8 electrons – Slightly negative Covalent bond (shared pair of electrons) + + Slightly positive Full shells with 2 electrons each Hydrogen atoms with unfilled shells

  42. WATER AND LIFE • Life on Earth began in water and evolved there for 3 billion years • The abundance of water is a major reason Earth is habitable • Your cells are composed of 70%–95% water

  43. The Structure of Water • The polarity of water results in • These interactions are called hydrogen bonds () Hydrogen bond () () () () () () () Fig 2.10

  44. Water’s Life-Supporting Properties • Hydrogen bonding explains most of water’s life-supporting properties: • Water as a solvent • Cohesion • Water moderates temperature • Ice floats

  45. 1. Water as the Solvent of Life • A solution is a liquid consisting of two or more substances evenly mixed Salt crystal Ion in solution Fig 2.14

  46. Dissolving of Sodium Chloride, NaCl, in Water Salt Electrical attraction Water molecules dissolve NaCl, breaking ionic bond Water Water molecules (H2O) Hydrogen bonds Ionic bond Edge of one salt crystal

  47. 2. Cohesion = attraction of identical molecules • Water molecules stick together as a result of hydrogen bonding Microscopic tubes

  48. Surface tension • is the measure of how difficult it is to stretch or break the surface of a liquid Fig 2.11 Figure 2.13

  49. 3. Water Moderates Temperature • Because of hydrogen bonding, water has a strong resistance to temperature change • How? • Earth’s Oceans cause temperatures to stay within limits that permit life

  50. 4. Ice floats • Water is less dense as a solid than as a liquid (due to hydrogen bonds!) • This allows fish and other organisms to survive under the ice.