General Biology: Biomolecules, Cell Structure, Membranes, Enzymes, and Cellular Respiration Study Guide

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Chapter 5: Biomolecules and Macromolecules

Polymers and Synthesis/Degradation

Biological macromolecules such as polysaccharides, fats, and proteins are polymers formed by linking monomers through specific chemical reactions.

Polymer Synthesis: Polymers are synthesized by dehydration synthesis (condensation reactions), where water is removed to form a bond between monomers.
Polymer Degradation: Polymers are broken down by hydrolysis, where water is added to break the bonds between monomers.
Example: Formation of a peptide bond between amino acids releases water; breaking the bond requires water.

Monosaccharides, Disaccharides, and Polysaccharides

Carbohydrates are classified based on the number of sugar units.

Monosaccharides: Simple sugars (e.g., glucose, fructose) with one sugar unit.
Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).
Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).
Functions: Energy storage (starch, glycogen), structural support (cellulose, chitin).

Fats and Fatty Acids

Fats are a type of lipid important for energy storage and insulation.

Triacylglycerol (Triglyceride): A fat molecule consisting of one glycerol and three fatty acids.
Saturated vs. Unsaturated Fatty Acids: Saturated fatty acids have no double bonds (solid at room temperature); unsaturated fatty acids have one or more double bonds (liquid at room temperature).
Effect of Saturation: Degree of saturation affects melting point and fluidity.

Steroids and Phospholipids

Steroids: Lipids with a four-ring structure; cholesterol is a common example.
Phospholipids: Major component of cell membranes, composed of two fatty acids, a phosphate group, and glycerol.
Common Element in Steroids: All steroids have a carbon skeleton with four fused rings.

Proteins and Amino Acids

Proteins are polymers of amino acids, which are linked by peptide bonds.

Amino Acids: 20 different types, each with a unique side chain (R group).
Protein Structure: Primary (sequence), secondary (alpha helix, beta sheet), tertiary (3D folding), quaternary (multiple polypeptides).
Denaturation: Loss of protein structure due to pH, temperature, or chemicals.
Stabilizing Bonds: Hydrogen bonds, disulfide bridges, ionic bonds, hydrophobic interactions.

Nucleic Acids: DNA and RNA

DNA vs. RNA: DNA contains deoxyribose, is double-stranded, and stores genetic information; RNA contains ribose, is single-stranded, and is involved in protein synthesis.
Nucleotide Structure: Each nucleotide has a phosphate group, a sugar, and a nitrogenous base.
Base Pairing: DNA bases pair via hydrogen bonds (A-T, G-C).

Chapter 6: Cell Structure and Organelles

Prokaryotic vs. Eukaryotic Cells

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, fungi, protists).

Major Organelles and Their Functions

Nucleus: Contains genetic material (DNA).
Mitochondria: Site of cellular respiration and ATP production.
Chloroplasts: Site of photosynthesis in plant cells.
Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
Lysosomes: Contain digestive enzymes for breakdown of macromolecules.
Vacuoles: Storage and structural support in plant cells.

Cytoskeleton and Cell Membrane

Cytoskeleton: Network of protein filaments (microtubules, microfilaments, intermediate filaments) that provide structural support and facilitate movement.
Cell Membrane: Composed of a phospholipid bilayer with embedded proteins; regulates entry and exit of substances.
Peripheral vs. Integral Proteins: Peripheral proteins are on the membrane surface; integral proteins span the membrane.

Chapter 7: Membrane Structure and Transport

Biological Membranes

Components: Phospholipids, proteins, cholesterol, carbohydrates.
Fluid Mosaic Model: Describes the dynamic and flexible nature of the membrane.

Transport Across Membranes

Passive Transport: Movement of substances down their concentration gradient without energy input (e.g., diffusion, osmosis).
Active Transport: Movement against the concentration gradient, requiring energy (ATP).
Endocytosis: Uptake of materials via vesicles (phagocytosis, pinocytosis, receptor-mediated endocytosis).
Exocytosis: Release of materials from the cell via vesicles.
Isotonic, Hypertonic, Hypotonic Solutions: Affect water movement and cell volume.

Table: Types of Membrane Transport

Type	Energy Required?	Direction	Example
Simple Diffusion	No	High to Low	Oxygen, CO2
Facilitated Diffusion	No	High to Low	Glucose via carrier protein
Active Transport	Yes (ATP)	Low to High	Na+/K+ pump
Osmosis	No	Water movement	Water across membrane

Chapter 8: Metabolism and Enzymes

Metabolic Pathways and Reactions

Spontaneous Reaction: Occurs without input of energy; increases entropy.
Anabolic Pathways: Build complex molecules from simpler ones (require energy).
Catabolic Pathways: Break down molecules to release energy.
Coupled Reactions: Energy from exergonic reactions drives endergonic reactions.

Enzymes and Enzyme Activity

Enzymes: Biological catalysts that speed up reactions by lowering activation energy.
Substrate: The reactant on which an enzyme acts.
Active Site: Region of enzyme where substrate binds.
Enzyme Inhibitors: Competitive inhibitors bind to the active site; noncompetitive inhibitors bind elsewhere, changing enzyme shape.
Allosteric Regulation: Regulation of enzyme activity by binding at a site other than the active site.
Optimum pH and Temperature: Each enzyme has specific conditions for maximum activity.
Feedback Inhibition: End product of a pathway inhibits an earlier step to regulate pathway activity.

Chapter 9: Cellular Respiration

Redox Reactions

Oxidation: Loss of electrons.
Reduction: Gain of electrons.
Redox Reaction: Chemical reaction involving transfer of electrons.

Stages of Cellular Respiration

Glycolysis: Occurs in cytoplasm; breaks glucose into pyruvate; produces ATP and NADH.
Citric Acid Cycle (Krebs Cycle): Occurs in mitochondrial matrix; completes breakdown of glucose; produces ATP, NADH, FADH2, and CO2.
Electron Transport Chain: Occurs in inner mitochondrial membrane; uses NADH and FADH2 to produce ATP via oxidative phosphorylation.
Oxygen: Final electron acceptor in the electron transport chain.
ATP Production: Most ATP is produced during oxidative phosphorylation in the electron transport chain.

Key Equations

Cellular Respiration Overall Equation:

ATP Yield: Complete oxidation of one glucose molecule yields up to 30-32 ATP molecules.

Table: Stages of Cellular Respiration

Stage	Location	Main Products
Glycolysis	Cytoplasm	2 ATP, 2 NADH, 2 Pyruvate
Citric Acid Cycle	Mitochondrial Matrix	2 ATP, 6 NADH, 2 FADH2, 4 CO2
Electron Transport Chain	Inner Mitochondrial Membrane	~26-28 ATP, H2O

Additional info: Some explanations and examples were expanded for clarity and completeness based on standard General Biology curriculum.