The Chemistry of Life

Characteristics of Life

  • All organisms:
    • Consist of cells
    • Grow and develop
    • Regulate metabolic processes
    • React to stimuli
    • Reproduce
    • Have DNA

Levels of Organization

  • Biosphere > Ecosystem > Community > Population > Organism > Body system > Organ > Tissue > Cell > Molecule > Atom

Elements of Life

  • 96% of living organisms are made of:
    • Carbon (C)
    • Oxygen (O)
    • Nitrogen (N)
    • Hydrogen (H)

Organic vs. Inorganic Compounds

  • Organic:
    • Contain carbon and hydrogen
    • Found in living organisms (except CO2CO_2)
  • Inorganic:
    • Do not contain carbon
    • Does not have a living origin

Biological Molecules

  • Organic compounds contain carbon, oxygen, and hydrogen. Also nitrogen and sulfur.
  • Inorganic compounds do not contain carbon.
  • Four groups of macromolecules:
    • Carbohydrates
    • Lipids
    • Proteins
    • Nucleic Acids

Macromolecules

  • Monomers: Smallest unit/building blocks.
  • Polymers: Large molecules formed by joining monomers.

Carbohydrates

  • Made of carbon, hydrogen, and oxygen ((CH<em>2O)</em>x(CH<em>2O)</em>x).
  • Hydrogen to oxygen ratio is 2:1.
  • Simple carbohydrates are sugars.
    • Pentose (5-sided): ribose and deoxyribose.
    • Hexose (6-sided): glucose and fructose.
  • Classes:
    • Monosaccharides: simple sugars (glucose, fructose, galactose).
    • Disaccharides: two monosaccharides (sucrose, maltose, lactose).
    • Polysaccharides: many sugars (starch, cellulose, glycogen).

Carbohydrate Reactions

  • Condensation: Monosaccharides join to form di- and polysaccharides; water is released.
  • Hydrolysis: Compound sugars break down into monosaccharides; water is required.

Lipids

  • Oily, greasy, or waxy organic compounds containing carbon, hydrogen, and oxygen (H:O ratio > 2:1).
  • Hydrophobic and soluble in organic solvents.
  • Classes:
    • Simple lipids: fats, oils, waxes.
    • Phospholipids.
    • Steroids.
  • Roles: energy storage, hormones, membrane structure.

Fats and Oils

  • Fats are solid at 20°C; oils are liquid.
  • Saturated fatty acids (animal) vs. unsaturated (plant).

Phospholipids

  • Glycerol + two fatty acids + phosphate group.

Steroids

  • Lipids with different structures (e.g., cholesterol, sex hormones).

Proteins

  • Macromolecules of amino acids linked as polypeptide chains.
  • Roles: enzymes, structural, transport, hormones, antibodies.

Amino Acids

  • Basic units of proteins (~20 types).
  • Peptide bond: bond between amino acids.
    • Di-/Tri-/Poly-peptide: 2/3/>4 Amino Acids

Protein Denaturation

  • Loss of 3D structure; usually irreversible.
  • Caused by:
    • Strong acids/bases
    • Heavy metals
    • Heat/radiation
    • Detergents/Solvents

Enzymes

  • Biological catalysts (proteins) that speed up reactions.
  • Substrate: compound acted upon by an enzyme.
  • Active site: region where substrate binds.
  • Enzyme-substrate complex forms.

Enzyme Models

  • Lock and Key: Substrate fits into enzyme's active site.

Enzyme Reactions

  • Catalysts lower activation energy.
  • Catabolic: Breakdown of larger molecules.
  • Anabolic: Formation of larger molecules.

Factors Affecting Enzyme Activity

  • Enzyme concentration
  • Substrate concentration
  • Temperature: Increase activity, until enzyme denaturation.
  • pH: Extremes can cause denaturation

Nucleic Acids

  • DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

DNA

  • Double-stranded, coiled, contains genetic information.
  • Nucleotides: phosphate group, deoxyribose sugar, nitrogen base (A, T, G, C).

RNA

  • Single-stranded, not coiled, instructs cells on protein synthesis.
  • Ribose sugar, uracil (U) instead of thymine (T).
  • Types: rRNA, mRNA, tRNA.

DNA vs RNA

  • DNA: double helix, deoxyribose, Thymine, A=T, G=C.
  • RNA: single-stranded, ribose, Uracil, A, U, G, C vary.

Vitamins

  • Organic compounds needed in small amounts for health and growth.
  • Assist in fighting infection, wound healing, and hormone regulation.
  • Water-soluble (B, C) vs. Fat-soluble (A, D, E, K) – know these.

Minerals

  • Inorganic salts ingested or absorbed for health.
  • Macro- vs. micronutrients (e.g., Ca vs. Fe).

Water

  • H2OH_2O; essential for metabolic reactions.
  • 60-70% of organisms.

Importance of Water

  • Solvent, reagent, support, temperature regulation, lubricant, transport.

Food Labels

  • Serving size, calories, % daily value, nutrients.