Cellular Respiration Overview

Cellular Respiration

• Anabolism vs. Catabolism:

  • Anabolism builds complex molecules from simpler ones, requiring energy. Examples include protein synthesis.
  • Catabolism breaks down complex molecules into simpler ones, releasing energy. Cellular respiration is an example.

• Energy Forms:

  • Kinetic energy is energy of motion (like molecular movement).
  • Potential energy is stored energy (like energy in chemical bonds).
  • Chemical energy is potential energy stored in molecules like glucose or ATP.

• ATP Structure and Function:

  • ATP (Adenosine Triphosphate) is a primary energy carrier.
  • It has adenine, ribose, and three phosphate groups with high-energy bonds.
  • Breaking a phosphate bond releases energy, forming ADP (Adenosine Diphosphate) and inorganic phosphate (Pi). ATP is unstable and thus not stored long-term.

• Cellular Respiration Steps:

  • Glycolysis (cytoplasm): Glucose is broken down to 2 pyruvate, producing 2 ATP and 2 NADH.
  • Pyruvate Oxidation (mitochondrial matrix): Pyruvate is converted to Acetyl-CoA, releasing CO₂ and producing NADH.
  • Krebs Cycle (mitochondrial matrix): Acetyl-CoA is further broken down, generating CO₂, ATP, NADH, and FADH₂.
  • Electron Transport Chain (ETC, inner mitochondrial membrane): Electrons from NADH and FADH₂ are passed through protein complexes. This creates a proton gradient used by ATP synthase to produce 32-34 ATP. Water is a product.

• Products of Each Step:

  • Glycolysis: 2 ATP, 2 NADH, 2 Pyruvate
  • Pyruvate Oxidation: 2 NADH, 2 CO₂
  • Krebs Cycle: 2 ATP, 6 NADH, 2 FADH₂, 4 CO₂
  • ETC: 32-34 ATP, H₂O

• Substrate-Level Phosphorylation:

  • ATP is directly formed by transferring a phosphate group from a molecule to ADP.
  • Occurs in Glycolysis and the Krebs Cycle

• Mitochondrial Events:

  • Matrix: Pyruvate oxidation and Krebs cycle take place here.
  • Inner Membrane: The ETC and ATP synthesis occur in the inner membrane.

• Specific ATP NADH, Water, and CO2 Production by Stages:

  • Specific results are noted with quantities of CO2, H2O, ATP and NADH produced in each step

Photosynthesis

• Light-Dependent and Calvin Cycle Products:

  • Light-Dependent Reactions (Thylakoid Membrane): Produce ATP, NADPH, and O₂.
  • Calvin Cycle (Stroma): Produces glucose.

• Photosystems: -Photosystem II (PSII) absorbs light, splits water, realizing oxygen and electrons.

  • Photosystem I (PSI) absorbs light and generates NADPH.

• Electron Flow (Light-Dependent):

  • Light excites electrons in PSII.
  • Electron transport chain from PSII to PSI creates a proton gradient for ATP production.
  • PSI re-energizes electrons to reduce NADP⁺ to NADPH.

• Rubisco:

  • Rubisco is a crucial enzyme in the Calvin Cycle.
  • Fixes CO₂ for glucose production though it is slow.

• Photosynthesis Efficiency:

  • Only 1-2% of light energy is transformed into chemical energy.
  • Photorespiration (Rubisco reacting with O2 instead of CO2) lowers efficiency.

• Chloroplast Events:

  • Thylakoid Membrane: Light-dependent reactions occur generating ATP and NADPH.
  • Stroma: Calvin Cycle utilizing ATP and NADPH to form glucose.

• Chloroplast Structure:

  • Labelled structures include the outer membrane, inner membrane, thylakoids (in stacks called grana), and stroma.

Test your knowledge on cellular respiration, including the differences between anabolism and catabolism. Learn about the forms of energy involved and the structure and function of ATP. Explore the key steps of glycolysis and how energy is produced in the process.