Unifying Characteristics of Life

1. Unifying Characteristics of Life • Order— the smallest unit of life is the cell • Metabolism— • Responsiveness—perceive and react to their environment • Development— • Heredity—genes are passed from parent to offspring • Evolution—populations change over time as they adapt

2. 4. Cell:The simplest entity that has all the properties of life Biological Organization Fig 1.3 3. Organelle: 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: 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 1. 2.

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

8. 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

9. The Unity and Diversity of Life EUKARYOTES Plants Animals Fungi Protists Bacteria Archaea: Bacteria adapted to extreme environments PROKARYOTES Universal Ancestor

10. The Three Domains of Life • The three domains of life are: • Bacteria • Archaea • Eukarya

11. Domain Archaea Domain Bacteria Domain Eukarya Kingdom Protista Kingdom Plantae Kingdom Animalia Kingdom Fungi Fig 1.9

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

13. EVOLUTION: BIOLOGY’S UNIFYING THEME • The history of life is a saga of a restless Earth billions of years old • Fossils document this history Fig 1.10

14. Life evolves Each species is one twig of a branching tree of life extending back in time Fig 1.11 Ancestral bear

15. Darwin’s book developed two main points 1. Descent with modification 2. Natural selection

16. 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

17. Descent with modification 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 Fig 1.13 Common ancestor from South American mainland

18. Darwin’s Conclusion • Fact 1: • Darwin synthesized the concept of natural selection from two observations: • Fact 2: • Conclusion: Unequal reproductive success

19. Fig 1.14: Natural Selection

20. The Evolution of Diversity • Different species have different traits. These arise from: • Mutations – – heritable changes in DNA. Mutations are adaptive if they change the organism’s ability to get food, mate, etc. • Evolution – • Natural selection - adaptive traits tend to increase over time. It is the mechanism of evolution

21. 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

22. BASIC CHEMISTRY • Organisms and all other things in the universe consist of matter • Matter is anything that occupies space and has mass

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

24. 25 Elements are essential to life • C, H, O, N: 96% of the weight of the human body Fig 2.3

25. Elements • Elements can combine to form compounds • Compounds • Examples of Compounds:

26. Atom: (a) Hydrogen atom (b) Carbon atom (c) Oxygen atom Proton Neutron Electron First shell Second shell Atomic nucleus Fig. 2.02

27. Atomic Structure • The subatomic particles of an atom Electron Proton Neutron Nucleus -Consists of neutrons and protons

28. Elements • Atomic Number: • Mass number sum of the number of protons and neutrons

29. Chemical Properties of Atoms • Electrons • The number of electrons in the outermost shell…

30. 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 Fig 2.7

31. Chemical Bonding and Molecules • Chemical reactions: • 2 types of molecular bonding: • Ionic Bonds • Covalent bonds

32. 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 2.8 Sodium chloride (NaCl)

33. 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

34. Covalent Bonds Fig 2.9

35. 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

36. 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

37. The Structure of Water • The polarity of water results in….. () Hydrogen bond () () () () () () () Fig 2.10

38. Water’s Life-Supporting Properties • Hydrogen bonding explains most of water’s life-supporting properties:

39. 1. Water as the Solvent of Life Salt crystal Ion in solution Fig 2.16

40. 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

41. 2. Cohesion = Microscopic tubes Fig 2.12

42. 3. Water Moderates Temperature • Because of hydrogen bonding, water has a strong resistance to temperature change • Water can absorb and store large amounts of heat while only changing a few degrees in temperature. • How?

43. The Four Most Important Organic Biological Compounds • Carbohydrates • Lipids • Proteins • Nucleic Acids

44. 1) Carbohydrates • C:H:O ratio is 1:2:1 (CH20)n • Simple sugars: • Structural units, used to make larger, storage compounds: • Starch – • Glycogen – • Cellulose –

45. Fig 3.13

46. Glucose Fructose Monosaccharides C6H12O6 (Simple sugars) Glucose Fructose Formation of a Disaccharide C12H22O11 H2O (water) Sucrose A portion of a polysaccharide

47. 2. Lipids • Non-polar, hydrophobic (don’t dissolve in water) • (CH)nCOOH • Functions:

48. A) Fats • Triglycerides – most abundant lipids in body, abundant energy!

49. Fig. 3.15