1.3 Biochemical Reactions

1.3 Biochemical Reactions

  • Focus on the study of chemical reactions important in biological processes.

Biochemical Reactions

1) Oxidation/Reduction (Redox) Reactions

  • Involve the transfer of electrons between molecules.

  • When one molecule undergoes oxidation, another molecule undergoes reduction.

2) Biological Context

  • In biological systems, redox reactions are characterized by the transfer of hydrogen atoms (H) between molecules.

Examples of Biochemical Reactions

Example 1: Photosynthesis

  • Chemical Equation: 6CO2 + 6H2O ➔ C6H12O6 + 6O2

    • Reduction Component: Carbon dioxide (CO2) is reduced to glucose (C6H12O6) by adding H atoms.

Example 2: Cellular Respiration

  • Chemical Reaction: C6H12O6 + 6O2 ➔ 6CO2 + 6H2O

    • Oxidation Component: Glucose (C6H12O6) loses electrons and hydrogens.

    • Reduction Component: Oxygen (O2) gains electrons and hydrogens.

2) Neutralization (Acid-Base) Reactions

Definitions

  • Acid: Proton (H+) donor.

  • Base: Proton (H+) acceptor.

Acid-Base Properties

  • pH Scale:

    • Acidic solutions have pH values less than 7 (high [H+] concentration).

    • Basic (alkaline) solutions have pH values greater than 7 (high [OH-] concentration).

Water as a Neutral Solution

  • Chemical Composition: H2O is neutral (H+ and OH- concentrations are equal).

Example: Blood pH Regulation

  • Normal blood pH: 7.35-7.45 (slightly basic).

    • Alkalosis: pH above 7.5 can cause dizziness.

    • Acidosis: pH between 7.1-7.3 can result in fatigue/vomiting.

    • Critical Range: pH below 7.0 or above 7.8 may lead to death.

Buffer Systems

  • Buffers help maintain pH by donating or accepting hydrogen ions as necessary.

Carbonic Acid-Hydrogen Carbonate Buffer System

When Blood is Too Acidic:

  1. Hydrogen carbonate + Hydrogen ions ➔ Carbonic acid.

  2. Carbonic acid dissociates into water + carbon dioxide.

  • This process decreases blood acidity.

When Blood is Too Basic:

  1. Carbon dioxide + Water ➔ Carbonic acid.

  2. Carbonic acid dissociates into hydrogen carbonate + hydrogen ions.

  • This process increases blood acidity.

11) Condensation Reactions

  • Definition: An anabolic reaction where small molecules combine to form larger ones, requiring energy and releasing water in the process.

  • Mechanism: Monomers join together by removing OH from one monomer and H from another creating a covalent bond.

Example of Condensation:

  • Monomer 1 + Monomer 2 ➔ Linked by covalent bond (releasing H2O).

12) Hydrolysis Reaction

  • Definition: "Hydro" = water; "lysis" = break apart. It's a catabolic reaction breaking down large molecules into smaller ones, releasing energy.

  • Mechanism: Water is used to facilitate the breakdown.