Metabolism, Photosynthesis and Reactions

• Metabolism is the sum of all chemical reactions in a living organism that sustain life
• Metabolism includes processes converting energy from nutrients into usable forms.
• Metabolism is divided into catabolism and anabolism.

Catabolism

• Catabolism releases energy through the breakdown of complex molecules into simpler ones
• Cellular respiration, where glucose breaks down to ATP, exemplifies catabolism.

Anabolism

• Anabolism stores energy through the synthesis of complex molecules from simpler ones, requiring energy
• Protein synthesis, where amino acids assemble into proteins, illustrates anabolism.

Photosynthesis Requirements

• Photosynthesis needs water, carbon dioxide, and sunlight
• Photosynthesis produces glucose
• Chlorophyll absorbs individual protons in the plant in photosynthesis

Photosynthesis Reactions

• Photosynthesis has a light-dependent and light-independent reaction

Light-Dependent Reactions (Calvin Cycle/Dark Reactions)

• Takes place in the thylakoid membrane of the chloroplast
• It requires light energy, Water (H2O), NADP+, and ADP as inputs
• Produces Oxygen (O2), ATP, and NADPH as outputs

Light-Dependent Key Events

• Photon absorption by chlorophyll occurs
• Water splitting (photolysis) occurs, and releases oxygen
• ATP and NADPH is then used to power the next stage

Light-Independent Reactions

• Light-independent reactions occur in the stroma of the chloroplast
• Light-independent reactions needs carbon dioxide (CO2), ATP, and NADPH
• Glucose (C6H12O6), ADP, and NADP+ are produced by light-independent reactions

Light-Independent Key Steps

• Carbon Fixation: CO2 is captured by RuBisCO and attached to RuBP.
• Reduction Phase: ATP and NADPH convert 3-PGA into G3P.
• Regeneration Phase: Some G3P is used to regenerate RuBP, allowing the cycle to continue.

Factors Affecting Photosynthesis

• Light intensity: Rate increase up to a certain point with more light
• Carbon Dioxide (CO2) Concentration: Higher levels of CO2 leads to rapid photosynthesis until saturation
• Temperature: Optimal range varies by plant species; extreme temperatures can impede process
• Water Availability: A lack of water inhibits the splitting of water molecules in the light reactions

Importance of Photosynthesis

• Functions as the primary energy source for most life forms
• Produces oxygen for aerobic organisms
• Photosynthesis forms the basis of the food chain
• It reduces atmospheric CO2, regulating Earth's climate.

Cellular Respiration

• Cellular respiration's purpose is to breakdown glucose and generate ATP
• Cellular respiration starts in the cytoplasm, then moves to the mitochondria

Cellular Respiration Types

• Aerobic Respiration: With oxygen, produces more ATP
• Anaerobic Respiration: Without oxygen, produces less ATP

Glycolysis

• Glycolysis occurs in Cytoplasm
• Reactants: Glucose, 2 ATP, NAD*
• Produces: 2 Pyruvate, 2 ATP (net), 2 NADH
• Glycolysis is the first respiration step
• It can occur without oxygen
• Glycolysis produces a small amount of ATP.

Krebs Cycle (Citric Acid Cycle)

• Krebs Cycle occurs in Mitochondrial Matrix
• Reactants: 2 Pyruvate (converted to Acetyl-CoA), NAD*, FAD
• Products: 6 CO2, 2 ATP, 8 NADH, 2 FADH2
• Krebs Cycle completes glucose breakdown
• It generates high-energy electron carriers (NADH & FADH2) for the next stage

Electron Transport Chain (ETC) & Oxidative Phosphorylation

• ETC & Oxidative Phosphorylation occurs in Inner Mitochondrial Membrane
• Reactants: NADH, FADH2, O2
• Products: 32-34 ATP, H2O
• ETC uses electrons from NADH & FADH2 to pump protons across the membrane
• Oxygen is the final electron acceptor, forming water
• ATP Synthase produces ATP via chemiosmosis

Metabolism encompasses all chemical reactions essential for life, divided into catabolism (energy release) and anabolism (energy storage). Photosynthesis requires water, carbon dioxide, and sunlight to produce glucose, facilitated by chlorophyll's light absorption. It involves both light-dependent and light-independent reactions stages.