Biological Molecules and Macromolecules

Introduction to Macromolecules

Macromolecules are large, complex molecules essential for life, including carbohydrates, proteins, lipids, and nucleic acids. They are formed by polymerization of smaller subunits called monomers.

• Monomer: A small molecule that can join with others to form a polymer.

• Polymer: A large molecule made up of repeating monomer units.

• Dehydration Synthesis: Chemical reaction that joins monomers by removing water.

• Hydrolysis: Chemical reaction that breaks polymers into monomers by adding water.

• Example: Glucose monomers join to form starch or glycogen via dehydration synthesis.

Additional info: Macromolecules are crucial for structure, function, and regulation of the body's tissues and organs.

Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as energy sources and structural components.

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined together (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Formula: General formula for monosaccharides:

• Example: Glycogen is a storage polysaccharide in animals.

Proteins

Proteins are polymers of amino acids and perform a wide range of functions, including catalysis, transport, and structural support.

• Amino Acid: Building block of proteins, containing an amino group, carboxyl group, and side chain.

• Peptide Bond: Covalent bond linking amino acids in a protein.

• Levels of Structure: Primary (sequence), secondary (alpha helix, beta sheet), tertiary (3D folding), quaternary (multiple polypeptides).

• Example: Hemoglobin is a quaternary protein that transports oxygen.

Cell Structure and Function

Prokaryotic vs. Eukaryotic Cells

Cells are the basic units of life, classified as prokaryotic or eukaryotic based on their structure.

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria).

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals).

• Key Organelles: Nucleus, mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus.

• Example: Plant cells contain chloroplasts for photosynthesis; animal cells do not.

Cell Membranes and Transport

The cell membrane regulates the movement of substances in and out of the cell, maintaining homeostasis.

• Phospholipid Bilayer: Fundamental structure of cell membranes.

• Transport Mechanisms: Passive transport (diffusion, osmosis), active transport (requires energy).

• Osmosis: Movement of water across a semipermeable membrane.

• Facilitated Diffusion: Movement of molecules via membrane proteins.

• Example: Sodium-potassium pump uses ATP to move ions against their concentration gradients.

Enzymes and Biological Reactions

Enzyme Structure and Function

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

• Active Site: Region on the enzyme where substrate binds.

• Substrate: The molecule upon which an enzyme acts.

• Enzyme-Substrate Complex: Temporary association during the reaction.

• Factors Affecting Activity: Temperature, pH, substrate concentration, inhibitors.

• Example: Amylase catalyzes the breakdown of starch into sugars.

Equation:

Cellular Respiration

Overview of Cellular Respiration

Cellular respiration is the process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

• Stages: Glycolysis, Krebs Cycle (Citric Acid Cycle), Electron Transport Chain.

• ATP: Adenosine triphosphate, the main energy currency of the cell.

• Equation:

• Example: Muscle cells use cellular respiration to generate energy for contraction.

Photosynthesis

Photosynthesis Process

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose.

• Location: Occurs in chloroplasts of plant cells.

• Stages: Light-dependent reactions and Calvin Cycle (light-independent reactions).

• Equation:

• Example: Photosynthesis provides oxygen and organic compounds for heterotrophic organisms.

Comparison Table: Prokaryotic vs. Eukaryotic Cells

Summary

These notes cover essential topics in General Biology, including macromolecules, cell structure, membranes and transport, enzymes, cellular respiration, and photosynthesis. Understanding these concepts is fundamental for further study in biological sciences.