Macromolecules and Their Functions

Macromolecules

• Four main macromolecules are essential for cell survival: carbohydrates, lipids, proteins, and nucleic acids.
• Each macromolecule is a large molecule composed of smaller repeating units called monomers.

Carbohydrates

• Function: Provide quick energy for the body.
• Structural components: Carbon, hydrogen, and oxygen (CH₂O ratio).
• Monomer: Monosaccharide (e.g., glucose).
• Examples: Glucose (most common monosaccharide), glycogen (animal energy storage), starch (plant energy storage), cellulose (plant structural component).
• Polysaccharides are long chains of monosaccharides.

Lipids

• Functions: Long-term energy storage, insulation, and plasma membrane formation.
• Structural components: Carbon, hydrogen, and oxygen (more carbons than oxygens).
• Monomer: Fatty acid.
• Examples: Phospholipids (plasma membrane component), cholesterol (can contribute to heart problems), steroids (sex hormones).
• Lipids are also known as fats.
• Lipids are hydrophobic (don't mix with water).

Proteins

• Functions: Act as the "workers" of the cell.
• Structural components: Carbon, hydrogen, oxygen, and nitrogen (CHON).
• Monomer: Amino acid.
• Examples: Hemoglobin (oxygen transport), insulin (blood sugar regulation), enzymes (catalyze chemical reactions).
• Many proteins end in "-ion" (e.g., insulin, collagen).

Nucleic Acids

• Functions: Store and transmit genetic information.
• Structural components: Carbon, hydrogen, oxygen, nitrogen, and phosphorus (CHONP).
• Monomer: Nucleotide.
• Examples: DNA (deoxyribonucleic acid), RNA (ribonucleic acid).

Enzymes

• Proteins that speed up chemical reactions.
• Also known as catalysts.
• Function by lowering activation energy, the amount of energy needed for a reaction to occur.
• Involved in breaking down and building molecules.

Enzyme Reactions

• Substrate: The molecule that the enzyme acts upon.
• Enzyme-substrate complex: The temporary combination of the enzyme and substrate.
• Products: The molecules resulting from the chemical reaction catalyzed by the enzyme.

5 Key Facts About Enzymes

• Shape and Function: The shape of an enzyme determines its function. The substrate fits perfectly into the enzyme's active site.
• Specificity: Enzymes are specific, meaning they only bind to one type of substrate.
• Reusability: Enzymes are not consumed during a reaction and can be used repeatedly.
• Denaturation: Enzymes can lose their shape (denature) due to high temperatures (fevers) or low pH (acidity).
• Activation Energy: Enzymes reduce the activation energy required for a reaction to occur, speeding up the process.

Enzyme Activity

• Enzymes speed up chemical reactions by lowering the activation energy needed for the reaction to occur.
• This makes the reactions happen faster.
• The graph illustrates this: the blue line represents a reaction without an enzyme (high activation energy, slow process), while the pink line depicts a reaction with an enzyme (lower activation energy, faster process).