UNIT THREE COMPREHENSIVE

Study Guide

Chapter 8: Metabolism

Key Terms

• Catabolic Process: A metabolic pathway that breaks down molecules into smaller units, releasing energy.

• Anabolic Process: A metabolic pathway that builds larger molecules from smaller units, consuming energy.

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy.

• Chemical Energy: Energy stored in chemical bonds.

• Gibbs Free Energy: A thermodynamic potential that measures the maximum reversible work that can be performed by a system at constant temperature and pressure.

• Exergonic Process: A spontaneous process that releases energy, characterized by a negative change in Gibbs free energy (ΔG < 0).

• Endergonic Process: A non-spontaneous process that requires energy to proceed, characterized by a positive change in Gibbs free energy (ΔG > 0).

• Spontaneous Process: A process that occurs without needing to be driven by an external force.

• Adenosine Triphosphate (ATP): The primary energy carrier in cells.

• ATP Cycle: The process of ATP formation and breakdown for energy utilization.

Gibbs Free Energy

• The sign of Gibbs free energy indicates whether a process is spontaneous (ΔG < 0) or non-spontaneous (ΔG > 0).

ATP Cycle

• Paired Reactions: Exergonic reactions drive endergonic reactions, effectively coupling the two types of processes. ATP is regenerated by coupling the endergonic formation of ATP from ADP and Pi (inorganic phosphate) with exergonic cellular processes.

• ATP Regeneration: ATP is regenerated from outside energy sources like glucose breakdown.

Role of ATP

• ATP serves as an energy currency in the cell, enabling endergonic processes to occur by coupling with exergonic reactions, thus facilitating cellular functions.

Enzyme and Reaction Terms

• Enzyme: A protein that acts as a catalyst to speed up chemical reactions.

• Substrate: The reactant that an enzyme acts on.

• Products: The substances formed as a result of a chemical reaction.

• Reaction Rate: The speed at which reactants are converted into products.

• Activation Energy (EA): The energy required to initiate a chemical reaction.

• Transition State: A high-energy state during the conversion of reactants to products.

• Enzyme-Substrate (ES) Complex: The temporary complex formed when an enzyme binds to its substrate.

• Active Site: The region of the enzyme where substrate binding occurs.

• Catalysis: The process of increasing the rate of a chemical reaction through the use of a catalyst.

Reaction Energy Diagram

• Identify reactants, transition states, activation energy, products, and whether a reaction is endergonic or exergonic on a reaction energy diagram.

Chapter 9: Cellular Respiration

• Steps of Cellular Respiration:

  1. Glycolysis: Occurs in the cytoplasm; breaks down glucose into pyruvate, yielding ATP.

  2. Pyruvate Oxidation: Occurs in the mitochondria; converts pyruvate into Acetyl CoA.

  3. Citric Acid Cycle (Krebs Cycle): Occurs in the mitochondrial matrix; completes the breakdown of glucose derivatives, releasing electron carriers.

  4. Oxidative Phosphorylation: Occurs in the inner mitochondrial membrane; generates ATP via electron transport and chemiosmosis.

• The breakdown of organic molecules releases energy as they are oxidized, which is an exergonic process.

• Substrate-Level vs. Oxidative Phosphorylation:

  • Substrate-Level Phosphorylation: Direct transfer of a phosphate group to ADP to form ATP; occurs in glycolysis and the citric acid cycle.

  • Oxidative Phosphorylation: ATP production via the electron transport chain and chemiosmosis; accounts for the majority of ATP synthesized in cellular respiration.

Chapter 41: Nutrition and Digestion

• Reasons Heterotrophs Consume Food:

  1. To obtain energy.

  2. To acquire building blocks for growth and repair.

• Essential Nutrients: Include essential minerals, vitamins, and amino acids which are necessary for survival.

  • Macro-nutrients: Required in larger quantities (e.g., carbohydrates, proteins, fats).

  • Micro-nutrients: Required in smaller quantities (e.g., vitamins, trace minerals).

• Digestion Types:

  • Intracellular Digestion: Occurs within cells, used by single-celled organisms.

  • Extracellular Digestion: Occurs in a digestive cavity, utilized by multicellular animals.

• Surface Area and Absorption: Greater surface area enhances nutrient absorption; in humans, the small intestine maximizes surface area with villi and microvilli.

• Alimentary Canal: A "tube within a tube" structure aiding in digestion and absorption.

• Structures of the Alimentary Canal: Includes the mouth, esophagus, stomach, intestines, etc. Core functions include mechanical breakdown, propulsion, digestion, absorption, and excretion.

• Accessory Digestive Structures:

  • Salivary Glands: Produce saliva aiding in digestion; connect to the oral cavity.

  • Pancreas: Produces digestive enzymes and hormones; connects to the duodenum.

  • Gallbladder: Stores bile; connects to the duodenum.

  • Liver: Produces bile and processes nutrients; connects via the hepatic duct.

• Digestive Differences:

  • Herbivores have longer digestive tracts with specialized chambers to ferment plant matter.

  • Carnivores tend to have shorter, simpler digestive systems adapted for meat processing.

Chapter 42: Circulation and Gas Exchange

• Animal Size and Surface Area: Smaller animals have a higher surface area to volume ratio, influencing gas exchange efficiency.

• Components of the Vertebrate Circulatory System: Varies by species; includes heart, blood vessels, blood.

• Definitions:

  • Artery: Blood vessels that carry blood away from the heart.

  • Vein: Blood vessels that carry blood towards the heart.

• Double Circulation Advantage: In mammals, it maintains efficient oxygenation of blood by separating pulmonary and systemic circuits.

• Path of Blood: Blood follows a specific pathway through the heart's chambers and valves (right atrium -> right ventricle -> lungs -> left atrium -> left ventricle -> body).

• Gas Exchange: Occurs in the alveoli of the lungs; oxygen diffuses into the blood while carbon dioxide diffuses out.

• Cardiac Cycle:

  • Systole: Contraction phase of the heart.

  • Diastole: Relaxation phase of the heart.

• Blood Vessel Types: Include arteries (thick walls), veins (thinner walls with valves), and capillaries (thin-walled for exchange).

• Capillary Beds: Allow for nutrient and gas exchange; controlled by precapillary sphincters.

• Blood Components: Major components include red blood cells (oxygen transport), white blood cells (immune function), platelets (clotting), and plasma (liquid transport).