11-Biología.Proteínas
Understanding Proteins and Their Structures
Introduction to Proteins
- The discussion begins with the importance of proteins in our diet, highlighting common perceptions about protein-rich foods like meat and bread.
- Proteins are large biomolecules composed of amino acids, which serve as their monomers. Each protein can consist of thousands of these amino acids.
Amino Acids and Genetic Coding
- The sequence and type of amino acids that form a protein are determined by DNA, specifically the genes located within it.
- The human body contains approximately 100,000 different proteins, each performing complex functions such as transport and recognition.
Functions of Proteins
- Examples include insulin (related to diabetes), hemoglobin (oxygen transport in blood), collagen (structural support), and receptors that help identify foreign substances like viruses or bacteria.
Protein Synthesis Process
- There are 20 distinct amino acids that combine to form proteins in three-dimensional structures. These amino acids link through covalent bonds known as peptide bonds.
Structural Levels of Proteins
- The primary structure is a linear chain; secondary structures include alpha helices and beta sheets formed from local folding.
- Tertiary structure represents the overall three-dimensional shape resulting from interactions between various parts of the polypeptide chain.
Quaternary Structure
- Some proteins consist of multiple tertiary structures combined into a more complex quaternary structure. This hierarchy includes primary, secondary, tertiary, and quaternary levels.
Protein Denaturation: Effects of Heat
Practical Example: Cooking an Egg
- When cooking an egg, the clear part (egg white) primarily consists of proteins. Heating causes these proteins to denature—losing their natural structure.
Denaturation Process Explained
- As heat is applied, quaternary and tertiary structures disintegrate while secondary structures also break down. This process results in the egg white turning opaque.
Hydrolysis vs. Denaturation
Consequences of Overheating
- If an egg is overheated (e.g., burnt), not only do higher-order structures break down but covalent peptide bonds may also be disrupted due to excessive energy input.
Hydrolysis Defined