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Chapter 2: The Chemical Level of Organization

Chapter 2: The Chemical Level of Organization. Introduction to Chemistry. Matter is made up of atoms Atoms join together to form chemicals with different characteristics Chemical characteristics determine physiology at the molecular and cellular level. Atomic Particles. Proton :

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Chapter 2: The Chemical Level of Organization

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  1. Chapter 2:The Chemical Level of Organization

  2. Introduction to Chemistry • Matter is made up of atoms • Atoms join together to form chemicals with different characteristics • Chemical characteristics determine physiology at the molecular and cellular level

  3. Atomic Particles • Proton: • positive, 1 mass unit • Neutron: • neutral, 1 mass unit • Electron: • negative, low mass

  4. Particles and Mass • Atomic number: • number of protons • Mass number: • number of protons plus neutrons • Atomic weight: • exact mass of all particles (daltons)

  5. Electron shell n p+ e p+ e e n + n p (c) Hydrogen-3, tritium Hydrogen-1 (electron-shell model) (b) Hydrogen-2 deuterium Isotopes • 2 or more elements with equal numbers of protons but different numbers of neutrons

  6. Elements in the Human Body Table 2–1

  7. How do atoms form molecules and compounds?

  8. Molecules and Compounds • Molecules: • atoms joined by strong bonds • Compounds: • atoms joined by strong or weak bonds

  9. Chemical Bonds • Ionic bonds: • attraction between cations (+) and anions (-) • Covalent bonds: • strong electron bonds • Non polar covalent bonds: equal sharing of electrons • Polar covalent bonds: unequal sharing of electrons • Hydrogen bonds: • weak polar bonds

  10. Ionic Bonds Are atoms with positive or negative charge Figure 2–3a

  11. Formed between atoms that share electrons Electron-Shell Model and Structural Formula Molecule Hydrogen (H2) H–H Oxygen (O2) O=O Carbon Dioxide (CO2) O=C=O Nitric Oxide (NO) N=O Covalent Bond Free Radicals: Ion or molecule that contain unpaired electrons in the outermost shell. - Extremely Reactive -Typically enter into destructive reactions -Damage/destroy vital compounds

  12. Hydrogen Bonds • Attractive force between polar covalent molecules • Weak force that holds molecules together • Hydrogen bonds between H2O molecules cause surface tension Figure 2–6

  13. How is it possible for two samples of hydrogen to contain the same number of atoms, yet have different weights? A.One sample has more bonds. B. One sample contains fewer electrons, decreasing weight. C. One sample contains more of hydrogen’s heavier isotope(s). D. One sample includes more protons, increasing weight.

  14. Both oxygen and neon are gases at room temperature. Oxygen combines readily with other elements, but neon does not. Why? A. Neon has 8 electrons in its valence shell, oxygen has only 6. B. Neon cannot undergo bonding due to its polarity. C. Neon is exergonic. D. Neon’s molecular weight is too low to allow bonding.

  15. Both oxygen and neon are gases at room temperature. Oxygen combines readily with other elements, but neon does not. Why? A. Neon has 8 electrons in its valence shell, oxygen has only 6. B. Neon cannot undergo bonding due to its polarity. C. Neon is exergonic. D. Neon’s molecular weight is too low to allow bonding.

  16. Which kind of bond holds atoms in a water molecule together? What attracts water molecules to one another? A. polar covalent bonds; hydrogen bonds B. ionic bonds; charge interactions C. hydrogen bonds; charge interactions D. covalent bonds; hydrogen bonds

  17. Why are chemical reactions important to physiology?

  18. Energy • Energy: • the capacity to do work • Work: • a change in mass or distance

  19. Forms of Energy • Kinetic energy: • energy of motion • Potential energy: • stored energy • Chemical energy: • potential energy stored in chemical bonds When energy is exchanged, heat is produced - cells cannot capture it or use it for work

  20. Break Down, Build Up • Decomposition reaction(catabolism): AB A + B • Synthesis reaction(anabolism): A + B AB • Exchange reaction(reversible): AB + CD AD + CB If Water is Involved: • Hydrolysis: A—B—C—D—E + H2O A—B—C—H + HO—D—E • Dehydration synthesis(condensation): A—B—C—H + HO—D—E A—B—C—D—E + H2O

  21. KEY CONCEPT • Reversible reactions seek equilibrium, balancing opposing reaction rates • Add or remove reactants: • reaction rates adjust to reach a new equilibrium

  22. How do enzymes control metabolism?

  23. Activation Energy • Chemical reactions in cells cannot start without help • Activation energy gets a reaction started Figure 2–7

  24. Materials in Reactions • Reactants: • materials going into a reaction • Products: • materials coming out of a reaction • Enzymes: • proteins that lower the activation energy of a reaction

  25. Energy In, Energy Out • Exergonic reactions: • produce more energy than they use • Heat will be the by-product • Endergonic reactions: • use more energy than they produce • Most chemical reactions that sustain life cannot occur unless the right enzymes are present

  26. In cells, glucose, a six-carbon molecule, is converted into two three-carbon molecules by a reaction that releases energy. How would you classify this reaction? A. endergonic B. exergonic C. decomposition D.B and C

  27. In cells, glucose, a six-carbon molecule, is converted into two three-carbon molecules by a reaction that releases energy. How would you classify this reaction? A. endergonic B. exergonic C. decomposition D.B and C

  28. Why are enzymes needed in our cells? A. to promote chemical reactions B. for chemical reactions to proceed under conditions compatible with life C. to lower activation energy requirements D. all of the above

  29. What is the difference between organic and inorganic compounds?

  30. Organic and Inorganic Molecules • Organic: • molecules based on carbon and hydrogen • Inorganic: • molecules not based on carbon and hydrogen

  31. Essential Molecules • Nutrients: • essential molecules obtained from food • Metabolites: • molecules made or broken down in the body

  32. Why is water so important to life?

  33. Properties of Water • Solubility: • water’s ability to dissolve a solute in a solvent to make a solution • Reactivity: • most body chemistry uses or occurs in water • High heat capacity: • water’s ability to absorb and retain heat • Lubrication: • to moisten and reduce friction Water is the key structural and functional component of cells and their control mechanisms, the nucleic acids

  34. Aqueous Solutions Polar water molecules form hydration spheres around ions and small polar molecules to keep them in solution Figure 2–8

  35. Electrolytes • Inorganic ions: conduct electricity in solution • Electrolyte imbalance seriously disturbs vital body functions

  36. Molecules and Water • Hydrophilic: • hydro = water, philos = loving • reacts with water • Hydrophobic: • phobos = fear • does not react with water

  37. Solutions • Suspension: • a solution in which particles settle (sediment) • Concentration: • the amount of solute in a solvent (mol/L, mg/mL)

  38. What is pH and why do we need buffers?

  39. pH: Neutral, Acid, or Base? • pH: • the concentration of hydrogen ions (H+) in a solution • Neutral pH: • a balance of H+ and OH— • pure water = 7.0 • Acid(acidic): pH lower than 7.0 • high H+ concentration, low OH— concentration • Base(basic): pH higher than 7.0 • low H+ concentration, high OH— concentration

  40. pH Scale • Has an inverse relationship with H+ concentration: • more H+ ions mean lower pH, less H+ ions mean higher pH Figure 2–9

  41. KEY CONCEPT • pH of body fluids measures free H+ ions in solution • Excess H+ ions (low pH): Acidosis • damages cells and tissues • alters proteins • interferes with normal physiological functions • Excess OH— ions (high pH): Alkalosis • Uncontrollable and sustained skeletal muscle contractions

  42. Controlling pH • Salts: • positive or negative ions in solution • contain no H+ or OH— (NaCl) • Buffers: • weak acid/salt compounds • neutralizes either strong acid or strong base

  43. Why does a solution of table salt conduct electricity, but a sugar solution does not? A.Electrical conductivity requires ions. B. Sugar forms a colloid, salt forms a suspension. C. Electricity is absorbed by glucose molecules. D. Table salt is hydrophobic, sugar is hydrophilic.

  44. How does an antacid help decrease stomach discomfort? A.by reducing buffering capacity of the stomach B. by decreasing pH of stomach contents C. by reacting a weak acid with a stronger one D. by neutralizing acid using a weak base

  45. Organic Compounds What kinds of organic compounds are there, and how do they work?

  46. Functional Groups of Organic Compounds • Molecular groups which allow molecules to interact with other molecules Table 2–4

  47. Carbohydrates • Consist of C:H:O in 1:2:1 ratio 1. Monosaccharides: • simple sugars with 3 to 7 carbon atoms (glucose) • Glucose: important metabolic fuel 2. Disaccharides: • 2 simple sugars condensed by dehydration synthesis (sucrose)

  48. Simple Sugars • Structural Formula: • Straight-chain form • Ring from • 3-D • Isomers: Glucose vs. Fructose: • - Same chemical formula • but different shape Figure 2–10

  49. Polysaccharides • Chains of many simple sugars (glycogen) • Formation: • Dehydration synthesis • Breakdown: • Hydrolysis synthesis Glycogen: made and stored in muscle cells Figure 2–12

  50. Carbohydrate Functions Polysaccharides Glycogen: made and stored in muscle cells Cellulose: structural component of plants -Ruminant Animals: Cattle, sheep, and deer Table 2–5

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