Study Notes on The Chemical Level of Organization

Chapter 2: The Chemical Level of Organization

1. Introduction

  • Importance of chemistry in understanding body composition and functions
  • All body activities are chemical reactions; familiarity with chemistry is crucial

2. Chapter Overview

  • Key Topics:
    • Matter
    • Chemical bonds
    • Chemical energy
    • Chemical reactions
    • Inorganic compounds
    • Organic compounds

3. Basic Principles

  • Chemistry: The science of the structure and interactions of matter
  • Matter: Anything that occupies space and has mass
    • Mass: Amount of matter in a substance
    • Weight: Force of gravity acting on a mass
  • Weight Change: Two methods to change weight:
    1. Increasing/decreasing mass
    2. Altering gravitational force (e.g., moving to a different planet)

4. Organization of Matter

  • Atoms: The building blocks of matter
  • Elements: Pure substances made up of the same type of atom
  • Chemical Characteristics: Determine physiological processes at molecular/cellular levels

5. Atomic Particles

  • Protons: Positively charged, with a mass unit of 1
  • Neutrons: Neutral charge, also with a mass unit of 1
  • Electrons: Negatively charged, with negligible mass compared to protons and neutrons

6. Electron Shells

  • Electron Cloud: Most probable electron location
  • Electron Capacity:
    • 1st shell: holds 2 electrons
    • 2nd shell: holds 8 electrons
  • Electrical Neutrality: Atoms usually have equal protons and electrons, resulting in a charge of 0

7. Particles and Mass

  • Atomic Number: Number of protons in the nucleus
  • Mass Number: Total of protons and neutrons in an atom
  • Atomic Weight: Exact mass of all particles in daltons

8. Isotopes

  • Definition: Atoms with the same number of protons but different neutrons
  • Radioactive Isotopes: Unstable isotopes that decay, useful in studying tissue structure/function

9. Ions

  • Ions: Charged atoms formed by gaining or losing electrons
    • Cations: Positively charged ions (e.g., Na+)
    • Anions: Negatively charged ions (e.g., Cl-)

10. Free Radicals

  • Definition: Electrically charged atoms/groups with unpaired electrons
  • Stability: Can stabilize by gaining/loss of an electron
  • Health Implications: Linked to conditions like cancer, diabetes, and accelerated aging; antioxidants (e.g., vitamins C and E) may mitigate damage

11. Chemical Bonds

  • Definition: Attractions that hold atoms in a molecule together
  • Bond Formation: Depends on the number of valence electrons
  • Types of Chemical Bonds:
    • Ionic Bonds: Attraction between cations and anions
    • Covalent Bonds: Strong bonds formed by sharing electrons
    • Hydrogen Bonds: Weak polar bonds important in large molecules and water cohesion

12. Detailed Insights on Chemical Bonds

  • Sodium Chloride Formation:
    • Na loses an electron → Na+ cation
    • Cl gains an electron → Cl- anion
    • Formation of NaCl (table salt) through ionic bonding
  • Covalent Bonding:
    • Sharing of electrons between atoms
    • Types of bonds based on electron sharing:
    • Single Bond: 1 pair shared
    • Double Bond: 2 pairs shared
    • Triple Bond: 3 pairs shared
  • Polar Covalent Bonds: Unequal sharing, example in water (H2O)
    • Oxygen's higher electronegativity causes partial charges
  • Hydrogen Bonds:
    • Important in establishing molecular connections and determining complex shapes of very large molecules (e.g., proteins)
    • High cohesion attributed to water's hydrogen bonds

13. Chemical Reactions

  • Definition: Process where bonds break/form, allowing molecular rearrangement
  • Metabolism: Sum of all chemical reactions in the body; follows the law of conservation of mass
    • Mass of reactants = Mass of products

14. Forms of Energy

  • Energy: Capacity to perform work
    • Kinetic Energy: Energy from motion; temperature reflects molecular motion
    • Potential Energy: Stored energy based on position, such as chemical energy in bonds
    • Law of Conservation of Energy: Total energy remains constant but can change form

15. Energy Transfer in Reactions

  • Exergonic Reactions: Release energy (e.g., breakdown during catabolism)
  • Endergonic Reactions: Require energy input (e.g., ATP needed for bond formation)
  • Coupled Reactions: Combine exergonic with endergonic to drive biological processes
  • Example: Energy from glucose breakdown is used to produce ATP

16. Activation Energy

  • Activation Energy: Minimum energy needed to initiate a reaction
  • Factors: Concentration and temperature can affect activation energy requirements

17. Catalysts and Enzymes

  • Catalysts: Speed up reactions by lowering activation energy without being consumed
    • They do not change energy differences between reactants/products
  • Enzymes: Biological catalysts that facilitate specific reactions in living organisms
    • Example: Lactase breaks lactose into glucose and galactose

18. Types of Chemical Reactions

  • Decomposition Reaction (catabolism): $AB
    ightarrow A + B$
  • Synthesis Reaction (anabolism): $A + B
    ightarrow AB$
  • Exchange Reaction: $AB + CD
    ightarrow AC + BD$
  • Reversible Reaction: $AB
    ightleftharpoons A + B$
  • Hydrolysis: $A—B—C—D + H_2O
    ightarrow A—B—H + HO—C—D$
  • Dehydration Synthesis: $A—B—H + HO—C—D
    ightarrow A—B—C—D + H_2O$

19. Oxidation-Reduction Reactions

  • Oxidation: Loss of electrons (decreases potential energy)
    • Often involves hydrogen loss
  • Reduction: Gain of electrons (increases potential energy)
  • Coupled oxidation-reduction reactions occur frequently in biological systems

20. Organic vs Inorganic Molecules

  • Organic Molecules: Contain carbon and hydrogen
  • Inorganic Molecules: Do not primarily consist of carbon and hydrogen

21. Essential Molecules

  • Nutrients: Essential molecules from food
  • Metabolites: Molecules created or degraded in the body

22. Water

  • Importance: Most abundant inorganic compound in living systems
  • Polarity: Water has a partial negative charge on oxygen and positive charges on hydrogens due to electron sharing

23. Properties of Water

  • Solubility: Ability to dissolve solutes in solvents
  • Reactivity: Most bodily reactions occur in water
  • High Heat Capacity: Capability to absorb and retain heat
  • Lubrication: Moisten and reduce friction

24. Aqueous Solutions

  • Hydration Shells: Polar water molecules surround ions and small polar molecules in solution

25. Electrolytes

  • Inorganic ions conducting electricity in solution, imbalances can disturb bodily functions

26. Hydrophilic and Hydrophobic Molecules

  • Hydrophilic: Molecules that interact with water
  • Hydrophobic: Molecules that do not react with water

27. Mixtures

  • Definition: Combination of elements/compounds physically blended and not chemically bound
    • Types of Liquid Mixtures:
    • Solution: Solvent dissolves solute
    • Colloid: Particles large enough to scatter light
    • Suspension: Mixture settles over time

28. pH

  • Definition: Concentration of hydrogen ions (H+) in a solution
  • Neutral pH: Balance of H+ and OH−, example pure water pH = 7
    • Acid: pH < 7 (high H+ concentration)
    • Base: pH > 7 (low H+ concentration)
  • pH Scale: Logarithmic scale; every unit change represents a tenfold difference in H+ concentration

29. Control of pH

  • Acidosis: Excess H+ leads to low pH, damaging cells and altering protein function
  • Alkalosis: Excess OH− leads to high pH, rarer issues
  • Buffers: Weak acids/salts that maintain pH stability

30. Organic Compounds

  • Characteristics: Large molecules containing carbon, hydrogen, and oxygen
  • Major Classes:
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic acids

31. Carbon Properties

  • Versatile and reactive with multiple bonding capabilities
  • Generally insoluble in water; forms strong stable structures
  • Mostly comprises covalent bonds and serves as an energy source

32. Functional Groups

  • Specific groups allowing molecules to interact with one another

33. Carbohydrates

  • Role: Primary energy source for life; includes sugars, starches, glycogen, and cellulose
  • Classification:
    • Monosaccharides: 3 to 7 carbon atoms (e.g., glucose, fructose, galactose)
    • Disaccharides: Formed by dehydration synthesis from monosaccharides (e.g., sucrose, maltose, lactose)
    • Polysaccharides: Largest carbohydrates like glycogen, stores energy

34. Clinical Application: Lactose Intolerance

  • Caused by lactase deficiency, leading to undigested lactose fermentation, causing gas

35. Lipids

  • Composition: Carbon, hydrogen, and oxygen atoms; primarily hydrophobic
  • Types:
    • Triglycerides
    • Phospholipids
    • Steroids
    • Eicosanoids
    • Lipoproteins
  • Comprise 18-25% of body weight

36. Triglycerides

  • Most abundant lipids, serve protective and energy functions; greater energy yield than carbs
  • Forms: Solid (fats) or liquid (oils); storage is nearly limitless

37. Saturation of Triglycerides

  • Depends on covalent bond types:
    • Saturated: Only single bonds
    • Monounsaturated: One double bond
    • Polyunsaturated: Multiple double bonds

38. Clinical Application: Essential Fatty Acids

  • Must be obtained from diet or supplements (e.g., omega-3 and omega-6)

39. Phospholipids

  • Key components of membranes, amphipathic (both hydrophilic and hydrophobic properties)
    • Consist of polar heads and nonpolar tails

40. Steroids

  • Characterized by four fused carbon rings; biologically significant substances include hormones and cholesterol

41. Eicosanoids

  • Derived from arachidonic acid; include prostaglandins and leukotrienes impacting a variety of physiological responses

42. Proteins

  • Most abundant organic molecules vital for numerous biological functions
  • Composition: Carbon, hydrogen, oxygen, nitrogen
  • Building Blocks: 20 amino acids

43. Protein Functions

  • Functions include:
    • Support: Structural proteins
    • Movement: Contractile proteins
    • Transport: For moving substances
    • Buffering: pH regulation
    • Metabolic regulation: Enzymatic functions
    • Coordination: Hormonal signaling
    • Defense: Antibodies fighting pathogens

44. Key Concept about Proteins

  • Control anatomical and physiological functions, shape, properties of tissues, and perform cell functions

45. Amino Acids and Peptides

  • Building blocks of proteinsforming chains, peptides, and polypeptides

46. Protein Structure

  • Primary Structure: Long chains of amino acids (polypeptides)
  • Secondary Structure: Hydrogen bonds create spirals (alpha helix) or pleats (beta sheet)
  • Tertiary Structure: Unique three-dimensional shapes from secondary structural folding
  • Quaternary Structure: Multiple tertiary structures come together

47. Enzymes

  • Definition: Catalysts that lower activation energy without being consumed
  • Characteristics: Highly specific, increase reaction rates significantly (up to 10 billion times)

48. Protein Denaturation

  • Protein functionality depends on its 3D shape, which can be altered by extreme conditions such as heat or acidity, leading to loss of function

49. Nucleic Acids: DNA and RNA

  • Nucleic Acids: Store and process genetic information
    • DNA: Genetic code encodes protein synthesis control
    • RNA: Relays instructions from nucleus for protein assembly on ribosomes

50. DNA Structure

  • DNA consists of nucleotides comprising nitrogen bases (A, T, G, C), a sugar, and a phosphate group

51. RNA Structure

  • RNA is single-stranded with ribose sugar and uses uracil instead of thymine; various forms include mRNA, rRNA, and tRNA

52. Adenosine Triphosphate (ATP)

  • Function: Energy storage molecule, powering various cellular activities (muscle contraction, substance transport, etc.)
    • Consists of three phosphate groups connected to adenine and ribose

53. Formation & Usage of ATP

  • ATP synthesis catalyzed by ATP synthase; energy from glucose can produce 36 to 38 ATP during respiration
  • Hydrolysis by ATPase releases energy for cellular processes, resulting in ADP (adenosine diphosphate)