8-Biología.Propiedades de las biomoléculas (I)

Understanding the Chemistry of Living Organisms

Introduction to Biochemistry

• The session focuses on the complex topic of biochemistry, emphasizing that living organisms are fundamentally composed of chemical substances and interactions.

• Key elements such as oxygen, nitrogen, sulfur, calcium, and iron are introduced as foundational components of life.

Atomic Structure and Interactions

• Atoms are described as the smallest units identifying different elements; they consist of a positive nucleus (protons) surrounded by electrons that carry energy.

• Discussion on atomic charges: atoms can be neutral or charged (positive/negative), which influences their interactions.

Types of Chemical Bonds

• Covalent bonds are highlighted as strong connections between certain atoms (carbon, hydrogen, oxygen, sulfur, nitrogen, phosphorus), crucial for biological molecules since they do not dissolve in water.

• Ionic bonds are explained using table salt (NaCl), where oppositely charged ions attract each other; these compounds dissolve in water.

Molecular Polarity and Solubility

• Molecules can be polar (like water), allowing them to interact well with other polar substances. Polar molecules have distinct positive and negative regions.

• Non-polar substances like oil do not mix with water due to lack of charge distribution; this property is termed hydrophobic.

Amphipathic Compounds

• Some compounds possess both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties; these are known as amphipathic substances.

• Phospholipids serve as an example of amphipathic molecules critical for cell membranes.

Practical Examples in Everyday Life

• A practical exercise involves adding various common substances to water to observe their solubility characteristics—oil floats while salt dissolves completely.

• The behavior of wax and sugar in water illustrates differences between hydrophobic and hydrophilic materials.

Conclusion on Molecular Behavior

• The discussion concludes with a visualization exercise regarding how amphipathic compounds behave in aqueous environments—polar parts interacting with water while non-polar parts remain separate.