This comprehensive study guide covers all the key concepts in AP Biology Unit 2, focusing on cellular energetics. We'll delve into the intricacies of enzyme function, cellular respiration, fermentation, and photosynthesis, equipping you with the knowledge and understanding needed to excel on the AP exam.
I. Enzyme Function & Regulation
This section lays the groundwork for understanding all metabolic processes. Mastering this material is crucial for success in Unit 2.
A. Enzyme Structure and Function
- Enzymes as Biological Catalysts: Understand how enzymes lower activation energy, speeding up reaction rates without being consumed in the process. Know the difference between catabolic and anabolic reactions.
- Enzyme-Substrate Specificity: Discuss the "lock and key" and "induced fit" models of enzyme-substrate binding. Explain the importance of the active site and its role in substrate binding and catalysis.
- Factors Affecting Enzyme Activity: Analyze the impact of temperature, pH, and substrate concentration on enzyme activity. Understand the concept of optimal conditions and how deviations from these affect enzyme function. Explain enzyme denaturation.
B. Enzyme Regulation
- Competitive vs. Non-competitive Inhibition: Distinguish between these two types of enzyme inhibition, providing examples of each. Understand how inhibitors affect the enzyme's active site and its catalytic activity.
- Allosteric Regulation: Explain how allosteric regulators (activators and inhibitors) bind to enzymes at sites other than the active site, influencing enzyme conformation and activity.
- Feedback Inhibition: Describe how feedback inhibition helps regulate metabolic pathways, preventing the overproduction of products.
II. Cellular Respiration
Cellular respiration is the process by which cells harvest energy from glucose. Understanding the stages and their respective products is essential.
A. Glycolysis
- Overview: Describe the process of glycolysis, including its location (cytoplasm), reactants (glucose), and products (pyruvate, ATP, NADH). Understand the net ATP gain.
- Energy Investment and Payoff Phases: Differentiate between these phases, outlining the key events and energy changes in each.
B. Krebs Cycle (Citric Acid Cycle)
- Overview: Describe the location (mitochondrial matrix), reactants (pyruvate), and products (ATP, NADH, FADH2, CO2) of the Krebs cycle.
- Decarboxylation and Redox Reactions: Understand the significance of these reactions in the Krebs cycle and their role in generating energy carriers.
C. Oxidative Phosphorylation (Electron Transport Chain & Chemiosmosis)
- Electron Transport Chain: Explain the role of the electron transport chain in creating a proton gradient across the inner mitochondrial membrane. Understand the role of oxygen as the final electron acceptor.
- Chemiosmosis: Describe how the proton gradient drives ATP synthesis via chemiosmosis, emphasizing the role of ATP synthase.
- ATP Yield: Calculate the total ATP yield from cellular respiration (considering both substrate-level and oxidative phosphorylation).
III. Fermentation
Fermentation provides an alternative pathway for energy production in the absence of oxygen.
A. Alcoholic Fermentation
- Process: Describe the process of alcoholic fermentation, including its products (ethanol, CO2). Identify the organisms that utilize this process.
B. Lactic Acid Fermentation
- Process: Describe the process of lactic acid fermentation, including its product (lactic acid). Identify the organisms that utilize this process.
IV. Photosynthesis
Photosynthesis is the process by which plants and other organisms convert light energy into chemical energy.
A. Light-Dependent Reactions
- Photosystems I & II: Explain the roles of photosystems I and II in capturing light energy and generating ATP and NADPH.
- Electron Transport Chain: Understand the role of the electron transport chain in the light-dependent reactions and its connection to chemiosmosis.
- ATP and NADPH Production: Describe how ATP and NADPH are generated during the light-dependent reactions.
B. Light-Independent Reactions (Calvin Cycle)
- Carbon Fixation: Describe the process of carbon fixation, involving the enzyme RuBisCo.
- Reduction and Regeneration: Outline the steps involved in reducing carbon dioxide to form glucose and the regeneration of RuBP.
- Products of the Calvin Cycle: Identify the final product of the Calvin cycle (glucose) and its importance in plant metabolism.
This study guide provides a solid framework for your AP Biology Unit 2 review. Remember to supplement this with textbook readings, practice problems, and past AP exam questions to solidify your understanding. Good luck!
