Chemical Reactions and Enzymes

Types of Chemical Reactions

• Neutralization reactions occur between an acid and a base, producing water (H₂O) and salt.
• Oxidation-Reduction (Redox) reactions involve the transfer of electrons.
• Oxidation is the loss of electrons (LEO = Lose Electrons Oxidation).
• Reduction is the gain of electrons (GER = Gain Electrons Reduction).
• Condensation reactions produce water molecules.
• Hydrolysis reactions use water molecules to break down substances.

Enzymes and Their Function

• Enzymes are proteins that accelerate biochemical reactions by lowering activation energy.
• Enzymes act as catalysts, speeding up reactions without being consumed.
• They are vital for life; almost all biochemical reactions rely on enzymes.
• Enzymes bind to the substrate (reactant) at their active site.
• The enzyme aids in converting the substrate into products.
• The enzyme is then available to be reused for subsequent reactions.
• Pepsin, a stomach enzyme, functions optimally in low pH (acidic) conditions.
• Trypsin, a small intestine enzyme, functions best at a higher pH.
• Inhibitors reduce or halt enzyme activity.
• Competitive inhibition occurs when an inhibitor binds to the active site, obstructing the substrate.
• Non-competitive inhibition happens when an inhibitor binds to an allosteric site, altering the enzyme's shape.
• Activators enhance enzyme activity.
• Lactase breaks down lactose.
• Lipase breaks down fats.

Basics of Eukaryotic Cell Structure

• The cell membrane regulates what enters and exits the cell.
• Phospholipids constitute the flexible membrane structure.
• Proteins assist in transport and signaling.
• Carbohydrates contribute to cell recognition.
• The fluid mosaic model describes the membrane's fluidity due to molecule movement.
• Intermolecular forces, rather than covalent bonds, hold the membrane together.

Transport Across the Cell Membrane

• Passive transport doesn't need energy.
• Simple diffusion involves molecules moving directly through the membrane.
• Facilitated diffusion utilizes transport proteins (channel proteins) to aid molecule movement across the cell membrane.
• Osmosis involves the diffusion of water through the cell membrane.
• In a hypertonic solution, water exits the cell, leading to cell shrinkage due to a higher solute concentration.
• In an isotonic solution, there's no overall water movement, and the cell size remains constant because the solute concentration is the same inside and outside the cell.
• In a hypotonic solution, water enters the cell, causing it to swell because there is a higher concentration inside the cell compared to outside.
• Active transport requires energy.
• It moves substances against their concentration gradient.
• Active transport always needs protein channels.
• Activity pumps move molecules out of the cell to create a low concentration inside but high concentration outside of the cell.
• Bulk transport moves large molecules or large amounts of a substrate across the cell membrane.
• Exocytosis ("Exit the Cell") moves large molecules or large quantities of substances out of the cell.
• During exocytosis, a vesicle within the cell merges with the cell membrane to release its contents outside.
• Examples include cells secreting hormones, enzymes, or waste products.
• Endocytosis ("Enter the Cell") moves large molecules or large amounts of substances into the cell.
• The cell membrane surrounds the substance during endocytosis, creating a vesicle that enters the cell.