Biochemistry of Cell Reactions

Study Notes

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.

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

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.

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

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

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

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