Chemistry in Biology

1. Organic Compounds

Organic Compounds

• Contain both Carbon (C) and Hydrogen (H) together

• Created by and found in living organisms

• Glucose C₆H₁₂O

• DNA

• Proteins

• Lipids

1. Inorganic Compounds

• Do not contain both C and H bonded together.

• Found in non-living matter (Earth, atmosphere)

• Water H₂O

• Carbon Dioxide CO₂

• Salts NaCl

2. The pH Scale & Ion Concentrations

• pH Scale Definition: Measures the relative concentration of hydrogen ions (\(H^{+}\)) in a solution.

• Scale Range: Ranges from 0 to 14, where 7 is completely neutral (pure water).

• Acidic Solutions: pH below 7. High concentration of \(H^{+}\) ions and low concentration of hydroxyl ions (\(OH^{-}\)).

• Basic (Alkaline) Solutions: pH above 7. Low concentration of H⁺ ions and high concentration of \(OH^{-}\) ions.

• Biological Consequences: Organisms use buffers to maintain homeostasis. Slight shifts in pH can destroy cellular structures and stop chemical reactions.

3. Biological Macromolecules: Structure & Function

Carbohydrates

• Monosaccharides: Single sugar units (e.g., glucose, fructose). Energy source.

• Disaccharides: Two sugars linked (e.g., sucrose, lactose). Transport sugar.

• Polysaccharides: Long sugar chains (e.g., starch, glycogen, cellulose). Storage and structure.

• Functional Groups: Contain hydroxyl (-OH) and carbonyl (C=O) groups.

🥑 Lipids

• Fatty Acids: Hydrocarbon chains with a carboxyl group (-COOH); can be saturated or unsaturated.

• Glycerol: A three-carbon alcohol that combines with fatty acids.

• Triglycerides: Three fatty acids attached to one glycerol. Long-term energy storage.

• Phospholipids: Form the structural basis of all cell membranes.

🥩 Proteins

• Amino Acids: The building blocks of proteins.

• Structure: Contain an amino group (\(-NH_{2}\)), a carboxyl group (\(-COOH\)), and a unique R-group (side chain).

• Functions: Enzymes, structural support, cell signaling, defense (antibodies).

🧬 Nucleic Acids

• Nucleotides: Building blocks containing a sugar, a phosphate group, and a nitrogenous base.

• DNA & RNA: Store and transmit genetic information for making proteins.

4. Enzyme Function & Specificity

• Enzyme Function: Biological catalysts that lower activation energy to speed up biochemical reactions.

• Substrate Specificity: Enzymes have a uniquely shaped active site. Only a specific substrate fits into it, like a lock and key.

• Denaturation: The unfolding or loss of an enzyme's 3D shape, making it completely nonfunctional.

• Denaturing Factors:

  • Extreme temperatures: High heat disrupts weak molecular bonds.

  • Extreme pH levels: Shifts in acidity alter ionic charges on the enzyme. Inhibitors and Activators: Molecules that can affect enzyme activity. Inhibitors decrease activity, while activators increase it.

5. Unique Properties of Water

• Cohesion & Adhesion: Water sticks to itself (cohesion) and other surfaces (adhesion), driving capillary action in plants.

• High Specific Heat: Water resists rapid temperature changes, stabilizing aquatic environments and global climates.

• Less Dense as a Solid: Ice floats because hydrogen bonds expand when frozen, insulating underlying liquid water for aquatic life.

• Universal Solvent: Polar water molecules dissolve other polar and ionic substances, allowing for cellular nutrient transport.

• Unique Properties: Water has several remarkable characteristics that play essential roles in biological systems.