The Chemistry of Life

I. ATOMS

• Definition: The smallest unit of an element that retains the properties of that element.

  • Components of an atom:

  • Proton: positively charged (+)

  • Neutron: neutral charge

  • Electron: negatively charged (-)

II. ELEMENTS

• Element: A substance made of one kind of atom.

• Molecule: Two or more atoms bonded together.

• Compound: A molecule made of more than one kind of atom.

III. WATER

• Chemical Formula: Water is composed of two hydrogen atoms and one oxygen atom (H₂O).

• Properties: Water possesses traits that hydrogen and oxygen do not have on their own, such as dissolving many compounds and constituting most of a cell.

IV. CARBON

• Importance: Life's essential compounds are carbon-based.

• Bonding Capability: Carbon can bond with up to four other atoms.

• Forms:

  • Creates long chains or rings.

• Organic Compound: Any compound containing carbon.

V. ESSENTIAL ORGANIC COMPOUNDS (Macromolecules)

• Types of macromolecules:

  • Carbohydrates

  • Lipids

  • Proteins

  • Nucleic Acids

VI. MACROMOLECULE STRUCTURE

• Composition: All macromolecules except lipids consist of smaller molecules linked into a long chain.

  • Monomer: One "link" in the chain.

  • Polymer: A chain of monomers linked together.

VII. CARBOHYDRATES

• Monomer: Monosaccharide

• Polymer: Polysaccharide

• Naming: Many carbohydrates have names that end in "-ose".

• Functions:

  • Energy Source: Short-term energy.

  • Cells break down monosaccharides like glucose to produce ATP.

  • Storage Polysaccharide:

  • Starch: Stores glucose in plants.

  • Glycogen: Stores glucose in animals.

  • Structural Polysaccharide:

  • Cellulose: Component of plant cell walls.

  • Chitin: Found in fungal cell walls and arthropod exoskeletons.

VIII. LIPIDS

• Definition: Lipids are not made of monomer chains like the other macromolecules.

• Characteristic: Hydrophobic - will not mix with water (nonpolar).

• Functions:

  • Energy Storage: Long-term energy storage (more efficient than carbohydrates).

  • Structure: Integral for cell membrane composition.

IX. STRUCTURE OF LIPIDS

• Types:

  • Triglycerides: Composed of glycerol and fatty acids.

  • Positions: Sn1, Sn2, Sn3 of glycerol.

  • Saturated vs Unsaturated fats:

  • Saturated: No double bonds between carbon atoms.

  • Unsaturated: At least one double bond between carbon atoms.

X. PHOSPHOLIPIDS

• Composition: Combines a hydrophilic phosphate "head" with hydrophobic fatty acid "tails".

• Cell Membrane Structure:

  • Comprised of two layers of phospholipids; fatty acids oriented inward, phosphate heads outward.

XI. PROTEINS

• Monomer: Amino acids (20 different kinds).

• Polymer: Polypeptides.

• Main Functions:

  • Speed up reactions (enzymes like Amylase).

  • Defense (antibodies).

  • Storage (Ovalbumin).

  • Transport (Hemoglobin).

  • Movement (motor proteins).

  • Structure (Keratin).

  • Communication (neurotransmitter receptors).

XII. ENZYMES

• Function: Biological catalysts that speed up reactions by lowering activation energy.

  • Key Components:

  • Activation Energy: The energy required to initiate a reaction.

  • Substrates: Reactants in enzyme-catalyzed reactions.

  • Mechanism:

  • Enzymes hold substrates in optimal orientation until the reaction completes, after which they are available for further reactions.

XIII. NUCLEIC ACIDS

• Monomer: Nucleotide

• Polymers: DNA and RNA.

• Structural Differences:

  • DNA: Double helix structure, stores blueprints for protein synthesis.

  • RNA: Single helix, assists in protein synthesis.

• Nucleotide Composition: Includes nitrogenous bases (Adenine, Cytosine, Guanine, Thymine in DNA; Uracil in RNA) and phosphate groups.

XIV. FUNCTION OF NUCLEIC ACIDS

• Role of ATP: Nucleotide that carries usable energy to a cell's biochemical reactions.

  • Energy Transfer: Mitochondria convert energy from glucose into ATP that cells can utilize.