Lecture Notes on Biological Macromolecules and Polymers

Lecture Notes on Biological Macromolecules and Polymers

Overview of Physiological Reactions

  • Recording Release: Lecture contents will be available after the lecture.
  • Physiological Conditions:
    • Reactions must occur under physiological conditions:
    • Mild temperatures
    • One atmosphere of pressure
  • Energy Requirements:
    • Biological processes are energy-intensive as they reverse disorder to create order.
    • Second Law of Thermodynamics:
    • States that closed systems move towards disorder (entropy).
    • Biological systems require energy input (from nutrients) to counteract this.

Macromolecules and Polymers

  • Definition of Macromolecules:
    • Large polymer molecules essential for life functions.
  • Example of Large Polymers:
    • Titin:
    • Involved in muscle contraction.
    • Composed of roughly 50 million structural units, illustrating the complexity and size of biological macromolecules.

Recycling and Hydrolysis Reactions

  • Importance of Recycling:
    • Biological macromolecules are periodically recycled through hydrolysis reactions.
    • Hydrolysis Reactions:
    • Breakdown of polymers into monomers (e.g., proteins to amino acids).
    • Essential for:
    • Nutrient extraction from food by breaking down proteins.
    • Recycling of unneeded or damaged proteins.

Dehydration Synthesis Reactions

  • Definition:
    • The process of creating a polymer from monomers.
  • Key Characteristics:
    • Asymmetric addition of single monomers at a time.
    • Energy Requirement:
    • Synthesis requires an energy input, facilitated by enzymes.

Polymerization and Breakdown

  • Polymers vs. Oligomers:
    • Terminology:
    • Poly-: Means many (e.g., polymers contain numerous monomer units).
    • Oligo-: Means few, typically referring to chains of around 5 to 50 units (e.g., oligonucleotides).
  • Synthesis Structure:
    • Polymers generally exhibit hierarchical structure which affects their function.

Protein Structure and Function

  • Secondary Structure of Proteins:

    • Local interactions within a polypeptide.
    • Types include:
    • Alpha Helix:
      • Characterized by coils held together by hydrogen bonds.
    • Beta Sheet:
      • Formed from chains lying adjacent to one another, stabilized by hydrogen bonds.
    • Key Points:
    • Secondary structures do not include side chains in hydrogen bonding.
    • Influences come from side chain conformations.

  • Tertiary Structure of Proteins:

    • Refers to the overall 3D structure formed due to interactions among various side chains.
    • Importance of Tertiary Structure:
    • Determines protein function.
    • Denatured proteins (e.g., heated) can lose their functionality and cannot return to native structure.

Enzymatic Activity in Biochemical Reactions

  • Enzyme Functionality Explained:
    • Enzymes catalyze reactions by:
    • Forming an active site for substrates.
    • Stabilizing a transition state and lowering activation energy needed for the reaction.
  • Dynamic Nature of Enzymes:
    • Enzyme structure is not static; they can move to facilitate reactions.
  • Post-Translational Modifications (PTMs):
    • Proteins undergo modifications after synthesis to enhance their function.
    • Example: Glycosylation and phosphorylation of proteins after they have been synthesized.

Conclusion

  • The structure of biological polymers greatly influences their function and interactions. Their dynamic processes include building (synthesis) and breaking down (degradation), which require energy and involve complex chemistry.