bio 3

Proteins

• Amino Acids: Building blocks of proteins; aspartic acid is represented as D or ASP.

• Polypeptide Chain: Formed from multiple amino acids.

Secondary Structure

• Folding: Proteins have local folding that forms structures like beta-pleated sheets and alpha helices.

  • Beta-Pleated Sheets: Chains are oriented in sheets with kinks, seen as colors in illustrations.

  • Alpha Helix: Chains spiral due to hydrogen bonds between amino acids spaced four positions apart.

• Both structures still exist within a single polypeptide chain.

Tertiary Structure

• 3D Folding: Further folding occurs making the structure take up more volume.

• Structure Dictates Function: Changes in primary structure (due to pH, temperature) can lead to denaturation and loss of function.

Energy Sources

• ATP: Essential for energy, derived similarly to fatty acids from stored energy sources.

• Cell Signaling: Proteins are crucial for cell communication, using hormones as messenger molecules.

Lipids

• Fat Functions: Used for long-term energy storage, insulation, and signaling.

• Hydrophobic Nature: Nonpolar lipids do not mix with water, making them hydrophobic.

• Types of Lipids: Include triglycerides, phospholipids, steroids, and waxes.

Triglycerides

• Structure: Composed of glycerol head and three fatty acid tails.

• Energy Storage: Breaking carbon bonds releases energy crucial for metabolism.

• Types of Fatty Acids:

  • Saturated: Solid at room temperature, fully bonded carbons.

  • Unsaturated: Liquid at room temperature, contains one or more double bonds, leading to kinks in structure that affect storage efficiency.

  • Monounsaturated: One carbon-carbon double bond.

  • Polyunsaturated: More than one carbon-carbon double bond.

• Health Implications: Saturated fats are easier to store; unsaturated fats can contribute to health issues.

Phospholipids

• Structure: Similar to triglycerides but with one fatty acid replaced by a phosphate group.

• Membrane Formation: Phospholipids create bilayers essential for cell membranes.

Carbohydrates

• Monosaccharides: Simple sugars with structures of 3 to 7 carbons, can form linear chains or stable rings.

• Disaccharides: Comprise two monosaccharides, bonded by glycosidic links (e.g. sucrose, lactose).

• Polysaccharides: Comprise many monosaccharides; types include:

  • Starch: Energy storage in plants.

  • Glycogen: Short-term energy storage in animals (stored in liver/muscles).

  • Cellulose: Provides structural support in plant cell walls.

  • Chitin: Structural material in fungal cell walls and exoskeletons of arthropods.