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.
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.
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.
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.
As amino acids bond, they form longer chains which create intricate three-dimensional structures.
Factors Influencing Protein Structure:
Hydrogen bonding
Hydrophobic interactions
Primary Structure:
Linear sequence of amino acids; determines all subsequent structures.
Secondary Structure:
Local folding patterns stabilized by hydrogen bonds (e.g., alpha helices, beta sheets).
Tertiary Structure:
Overall three-dimensional shape of a polypeptide influenced by the interactions of R groups.
Quaternary Structure:
Arrangement of multiple polypeptide chains into a complex protein.
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.
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.
Proteins are vital for nearly all biological processes in the body, functioning in both intracellular and extracellular environments.