wk 3 proteins

Overview of Proteins

• Proteins are essential molecules with diverse functions in living organisms.

• They are the most abundant organic molecules in our bodies and in nature.

• Proteins are large, complex molecules crucial for the structure, function, and regulation of tissues and organs.

Structure of Proteins

Building Blocks: Amino Acids

• Amino acids are the monomers of proteins, each having a central carbon atom.

• Key functional groups:

  • Amino Group: Contains nitrogen (–NH2).

  • Carboxyl Group: Composed of carbon, two oxygens, and one hydrogen (–COOH).

  • R Group: Determines the specific properties and diversity of amino acids.

Types of Amino Acids

• There are 20 different amino acids, each with unique R groups.

• Examples of Amino Acids:

  • Glycine: R group is one hydrogen; crucial for collagen structure and nerve impulse transmission.

  • Cysteine: Contains sulfur; stabilizes protein folding and provides structure.

  • Tryptophan: More complex structure; aids in protein production, enzyme functions, and neurotransmitter synthesis.

Formation of Peptides

• Peptide bonds form when amino acids undergo dehydration synthesis (a process that links monomers to form polymers).

• Types of peptides:

  • Dipeptide: Formed from two amino acids.

  • Tripeptide: Formed from three amino acids.

  • Polypeptide: A chain longer than three amino acids.

Protein Folding and Structure

• As amino acids bond, they form longer chains which create intricate three-dimensional structures.

• Factors Influencing Protein Structure:

  • Hydrogen bonding

  • Hydrophobic interactions

Levels of Protein Structure

1. Primary Structure:

   • Linear sequence of amino acids; determines all subsequent structures.

2. Secondary Structure:

   • Local folding patterns stabilized by hydrogen bonds (e.g., alpha helices, beta sheets).

3. Tertiary Structure:

   • Overall three-dimensional shape of a polypeptide influenced by the interactions of R groups.

4. Quaternary Structure:

   • Arrangement of multiple polypeptide chains into a complex protein.

Sensitivity of Proteins

• Proteins are sensitive to environmental factors, which can disrupt their structure:

  • Heat: High temperatures can lead to protein denaturation (unfolding).

  • pH Changes: Extreme shifts in pH can alter protein structure and bonding.

Importance of Proteins in Health

• Proteins have various roles in the body:

  • Structural Proteins: e.g., Collagen, essential for skin elasticity and tissue integrity.

  • Muscle Proteins: Myosin and actin are crucial for muscle contraction.

  • Transport Proteins: Facilitate movement of substances within the body.

  • Storage Proteins: Example includes albumin, which can change structure with temperature.

  • Digestive Enzymes and Antibodies: Essential for metabolism and immune response.

Conclusion

• Proteins are vital for nearly all biological processes in the body, functioning in both intracellular and extracellular environments.