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.

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