Key Concepts of Water and Carbon Chemistry in Biology

Hydrogen Bonds:

• Certain molecules, like water ($H_2O$), exhibit hydrogen bonding due to partial charges; oxygen is slightly negative, while hydrogen is slightly positive.
• These bonds are weak and constantly break and reform as water molecules vibrate and move.

Hydrophilic vs. Hydrophobic:

• Hydrophilic (water-loving) substances are polar or ionic and interact with water (e.g., salts, sugars).
• Hydrophobic (water-fearing) substances are nonpolar and do not interact with water (e.g., oils, methane).

Effects of Water’s Properties:

• Water's high heat capacity means it can absorb a lot of energy without a significant temperature change, helping to stabilize temperatures in biological organisms and environments.
• Cohesion in water allows for effective transport in plants, as water molecules can pull each other along in the xylem by evaporation from leaves.

States of Matter:

• States (solid, liquid, gas) relate to the movement of molecules; solids have less movement than liquids, which have less than gases.
• Absolute zero is theorized as a point where molecular movement stops entirely.

Molecular Interactions:

• Molecules can undergo reactions that result in different structural or functional properties (isomers) depending on the bonds between them.
• For example, single bonds allow rotation whereas double/triple bonds do not, contributing to molecular stability and shape.

Carbon Chemistry:

• Carbon forms the backbone of biological molecules; it typically forms four covalent bonds, which can be polar or nonpolar.
• Various functional groups attached to carbon can determine the polarity and solubility of molecules (e.g., -OH, -COOH increase solubility).

Biological Importance of Water:

• Water is essential for life due to its properties that facilitate biological processes, including nutrient transport and temperature regulation.