Cellular Respiration Quiz

Cellular Respiration

• Cellular respiration is a series of metabolic processes that occur within a cell. These processes harvest energy from organic substances like glucose.
• The energy is stored in energy-carrying biomolecules, such as ATP, for use in energy-requiring activities of the cell.

Objectives

• Differentiate anabolism from catabolism
• Relate the structure and function of NADH and FADH2 in metabolism and their corresponding enzymes.
• Differentiate and calculate ATP synthesis in oxidative phosphorylation and substrate-level phosphorylation.
• Describe the enzymes, co-factors, regulation and other molecular mechanisms of glycolysis, pyruvate reduction, Krebs cycle and Electron Transport Chain.
• Account for the net ATP and NADH production at the end of glycolysis, Krebs cycle (aerobic) and pyruvate (anaerobic) reduction.
• Account for the net ATP using the two major shuttle systems used by eukaryotic cells.

Cellular Metabolism Overview

• Cellular respiration is a series of metabolic processes.
• The processes take place within a cell.
• The biochemical energy harvesting occurs from organic substances.
• The energy is stored in energy-carrying biomolecules (e.g. ATP).
• The stored energy is used for energy-requiring activities of the cell.

Mitochondria

• Mitochondria are organelles with specific parts.
• Parts include outer membrane, inner membrane, matrix and ribosome.
• DNA is also found within mitochondria.

Anabolism vs Catabolism

• Anabolism: Builds complex molecules from simpler ones using energy (endergonic). Involves condensation reactions (water is a product). Photosynthesis is an anabolic process.
• Catabolism: Breaks down complex molecules into simpler ones, releasing energy (exergonic). Involves oxidation and hydrolysis reactions (water is a reactant). Cell respiration is a catabolic process.

How is work done in a cell?

• Mechanical Work: Chromosomal movement, beating of flagella, muscle contraction, active transport.
• Chemical Work: Synthesis of macromolecules, synthetic processes (e.g., building proteins).

ATP Molecule

• ATP (adenosine triphosphate) is a high-energy molecule.
• It has an adenine base, a ribose sugar, and a triphosphate chain (3 phosphate groups).
• Phosphoanhydride bonds link the phosphate groups, storing energy.

Methods of ATP production

• Substrate Level: Enzyme-catalyzed transfer of phosphate directly to ADP from a phosphorylated intermediate.
• Oxidative: ATP synthase uses a proton gradient across the inner mitochondrial membrane to generate ATP.

High-Energy Molecules (NADH and FADH2)

• NADH: Nicotinamide adenine dinucleotide. Yields three ATP during oxidative phosphorylation.
• FADH2: Flavin adenine dinucleotide. Yields two ATP during oxidative phosphorylation.

Co-enzymes of Biological Oxidation (NADH vs. FADH2)

• NADH: Ubiquitous coenzyme, adenine and nicotinamide nucleotides, produced in glycolysis and Krebs cycle. Transfers electrons to cytochrome complex I.
• FADH2: Riboflavin as the core component, adenine and flavine mononucleotide nucleotides, produced during Krebs cycle. Transfers electrons to cytochrome complex II.

Glycolysis

• Location: Cytoplasm
• Reactant: Glucose
• Major Product: 2 Pyruvates
• Byproduct: None
• ATP: 2

Pyruvate Oxidation

• Converts pyruvate into acetyl-CoA.
• Occurs in the mitochondria.
• Releases carbon dioxide.
• Reduces NAD+ to NADH.

Krebs Cycle (Citric Acid Cycle)

• Location: Mitochondrial matrix
• Reactant: Pyruvate
• Major Product: NADH, FADH2
• Byproduct: CO2
• ATP: 2

Oxidative Phosphorylation

• Location: Inner mitochondrial membrane
• Reactant: NADH, FADH2
• Major Product: ATP
• Byproduct: H2O
• ATP: 28 or more

ATP Synthase

• Enzyme that generates ATP from ADP and inorganic phosphate.
• Utilizes a proton gradient across the inner mitochondrial membrane.

Energy Yield

• Total ATP yield from glucose breakdown via cellular respiration is typically 36 to 38 ATP molecules. (This varies somewhat based on the shuttle system used and other considerations.)

Regulation of Cellular Respiration

• Allosteric Regulation: Enzymes regulated by binding to regulatory sites.
• Feedback Inhibition: End product inhibits early enzymes.
• Substrate Availability: Amount of substrate influences the rate.
• Hormonal Control: Hormones control.
• Energy Charge of the Cell: Energy status influences the rate.
• Oxygen Availability: Energy production depends on oxygen.
• Gene Expression: Gene regulation influences the expression of enzymes involved in cellular respiration.

Applications: Cyanide Toxicity and Type 2 Diabetes

• Cyanide: Inactivates cytochrome oxidase, blocking the electron transport chain, therefore affecting energy production.
• Type 2 Diabetes: Involves mitochondrial dysfunction, oxidative stress, and reduced antioxidant levels affecting glucose regulation.

Additional Note

• The document contains a quiz on photosynthesis and cellular respiration.
• The provided 'cheat sheet' is about cellular respiration.

Test your understanding of cellular respiration, including the metabolic processes involved in energy production and conversion. This quiz will evaluate your knowledge on ATP synthesis, glycolysis, the Krebs cycle, and the Electron Transport Chain. Key concepts such as anabolism, catabolism, and the roles of NADH and FADH2 are also covered.