Energy CRAM

General Overview

• ATP Creation

  • Begins with ADP (Adenosine Diphosphate), which has 2 phosphates.

  • Adding another phosphate through phosphorylation creates ATP (Adenosine Triphosphate).

  • This process is endergonic, meaning it requires energy input.

  • ATP Synthase: the enzyme responsible for synthesizing ATP.

• Quick Energy Storage

  • ATP is a reactive molecule that releases energy quickly, making it suitable for immediate use.

    • Combines negatively charged phosphates that repel each other, creating potential energy.

• Cellular Use of ATP

  • ATP is the primary energy carrier in cells, crucial for various processes including:

    • Cell Cycle: ATP is essential for cell division and overall cellular metabolism.

    • Building Polymers: ATP helps assemble monomers into polymers.

    • Movement: Required for muscle contractions.

    • Active Transport: ATP powers the movement of substances against their concentration gradients.

    • Cell Communication: ATP plays a role in signaling pathways.

Photosynthesis

• Active vs. Passive Transport

  • Passive Transport:

    • Simple Diffusion: Molecules move from high to low concentration without energy input.

    • Facilitated Diffusion: Larger or hydrophilic molecules require assistance from transport proteins but still move high to low concentration without energy.

  • Active Transport: Requires energy to move molecules from low to high concentration, often through a transport protein.

• Light Wavelength Absorption

  • Chlorophyll: Primarily absorbs violet, blue, orange, and red wavelengths.

    • Green Light: Around 550 nm, is reflected and thus not utilized, making plants appear green.

• Location of Photosynthesis

  • Occurs within chloroplasts:

    • Thylakoids: Contain light-absorbing pigments, where light-dependent reactions occur.

    • Stroma: Aqueous space where the Calvin cycle (light-independent phase) takes place, synthesizing sugars.

• Stages of Photosynthesis

  • Light-Dependent Reactions: Require sunlight, producing ATP and NADPH in thylakoids.

  • Calvin Cycle: Does not require light, utilizes ATP and NADPH to convert carbon dioxide into glucose in the stroma.

• Photosynthesis Reaction

  • Reaction: 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2 in chloroplasts.

• Role of Oxygen in Photosynthesis

  • Oxygen is released during the splitting of water molecules to replace energized electrons in chlorophyll, exiting through stomata.

• Electron Transport Chain

  • Initially, energized electrons from chlorophyll navigate through an electron transport chain, pumping hydrogen ions and creating a concentration gradient.

  • Electrons ultimately help produce NADPH and ATP used in the Calvin cycle.

Cellular Respiration

• Entry Points for Organic Molecules

  • Entirely dependent on glycolysis for carbohydrates, which yield pyruvate ready for further processing in the mitochondria.

  • Amino acids and fatty acids provide alternative pathways for energy production.

• Stages of Aerobic Respiration

  • Sequence: Glycolysis → Krebs Cycle → Electron Transport Chain.

  • Glycolysis occurs in the cytoplasm, while the Krebs cycle and oxidative phosphorylation take place in the mitochondria.

• Production of ATP

  • Glycolysis: 2 ATP, 2 NADH, 2 pyruvate.

  • Krebs Cycle: 2 ATP, 8 NADH, and 2 FADH2.

  • Electron Transport Chain: Up to 34 ATP can be produced.

• Electron Transport Chain Mechanism

  • Energized electrons from NADH and FADH2 pass through proteins, establishing ATP while oxygen acts as the final electron acceptor to form water.

• Energy Release

  • Energy not stored in ATP during cellular metabolism is released as heat, aiding in thermoregulation for endothermic organisms.

• Comparison: Aerobic vs. Anaerobic Respiration

  • Aerobic Respiration: High ATP yield (~38 ATP), utilizes oxygen, and occurs in both eukaryotes and prokaryotes.

  • Anaerobic Respiration: Low yield (2 ATP), occurs without oxygen, primarily in anaerobic bacteria and some eukaryotes (like yeast).

• Fermentation Types

  • Alcoholic Fermentation: Produces alcohol and carbon dioxide.

  • Lactic Acid Fermentation: Produces lactic acid; occurs in human muscle cells during high demand for energy when oxygen is temporarily insufficient.