Biochemistry of Cell Reactions

Chemical Reactions in Cells

• Nutrients essential for cell metabolism include carbohydrates (glycosidic bonds), proteins (peptide bonds), and lipids (ester bonds).
• Key reactions involve the removal of CO2 from amino acids to form amines and the hydrolysis of glycosidic bonds.

Metabolites

• Primary Metabolites: Necessary for life; include amino acids, nucleic acids, sugars, lipids, and vitamins.
• Secondary Metabolites: Not essential for growth but may provide benefits; examples are essential oils, toxins, and drugs.

Metabolic Pathways

• Metabolic pathways function like traffic flows in a city, with a defined rate and direction.
• Two main types of metabolic pathways:
  • Anabolic (Biosynthetic): Constructive processes forming complex molecules from simpler ones; requires energy (e.g., photosynthesis, protein synthesis).
  • Catabolic: Destructive processes breaking down complex molecules to simpler ones; releases energy (e.g., glycolysis, respiration).

Energy and ATP

• Energy from catabolism is stored in chemical bonds, primarily within adenosine triphosphate (ATP), the main energy currency in living organisms.

Enzymes

• Enzymes are biological catalysts that speed up biochemical reactions without being consumed in the process.
• All enzymes are proteins, but not all proteins serve as enzymes.
• Substrates are the chemicals acted upon by enzymes, converting them into products with specificity.
• Enzymes lower the activation energy required for reactions and are sensitive to temperature changes.
• Thermophilic enzymes are stable at high temperatures and exhibit specialized structures called active sites where substrates bind.

Ribozymes

• Certain RNA molecules, known as ribozymes, can act as enzymes, catalyzing specific reactions.

Carbonic Anhydrase

• Among the fastest enzymes, carbonic anhydrase accelerates the formation of bicarbonate (H2CO3) significantly, achieving up to 600,000 molecules per second in its presence.

Glycolysis and Enzymatic Steps

• The glycolysis pathway for glucose (C6H12O6) involves ten different enzymes, highlighting the specificity and diversity of enzymatic catalysis.

Chemical Bond Reactions

• Chemical reactions involve bond breaking and forming, exemplified by reactions like:
  • Ba(OH)2 + H2SO4 → BaSO4 + 2H2O (inorganic)
  • Starch + H2O → Glucose (organic)

Rate of Reaction

• The rate of a chemical reaction is calculated as the amount of product formed per unit time.