Photosynthesis and Cellular Respiration Flashcards

Biochemical Pathways and Energy Production

Objectives

• Describe photosynthesis and cellular respiration.

• Investigate the relationship between photosynthesis and cellular respiration.

• Recognize the significance of key components and processes.

Biochemical Pathway

• Also known as a metabolic pathway.

• Sequence of linked biological reactions catalyzed by enzymes.

• Metabolism: Sum of chemical reactions inside a cell.

• Energy metabolism: Generating energy from nutrients.

Catabolism vs. Anabolism

• Catabolism:

  • Breakdown of complex molecules into simpler ones.

  • Exergonic (energy released): Cellular Respiration

• Anabolism:

  • Building up of simple molecules into more complex ones.

  • Endergonic (energy absorbed): Photosynthesis

Photosynthesis

• A CO2 requiring process that combines H2O with light energy to generate glucose and oxygen.

• Occurs in the chloroplast.

• General equation:

  • CO2 + H2O \xrightarrow{\text{Light, Chlorophyll}} C6H{12}O6 + O2

Photosynthesis - Light Dependent Reaction

• Light/Hill reaction.

• Occurs on the thylakoid.

• Produces oxygen, ATP, and NADPH using light and water.

• Requires sunlight.

Photosynthesis - Light Independent Reaction

• Calvin-Benson Fixation/ Dark reaction.

• Occurs in the stroma.

• Uses ATP and NADPH from the light reaction.

• Uses CO_2 to produce carbohydrates (glucose).

• Can occur without light.

Light Dependent Reaction

• Involves Photosystems I and II.

• Water is split to produce oxygen, electrons, and hydrogen ions (O_2 + 2H^+).

• ATP and NADPH are produced.

Light Independent Reaction (Calvin Cycle)

• Occurs in the stroma.

• Involves carbon fixation, reduction, and regeneration of RuBP.

• Key components include RuBisCO, 3-PGA, GA3P, and RuBP.

• Produces 1/2 molecule of glucose (C6H{12}O_6).

Carbon Fixation

• C3, C4, and CAM plants use different mechanisms for carbon fixation.

Cellular Respiration

• Process requiring oxygen where glucose is broken down to produce ATP, with carbon dioxide as a byproduct.

• Occurs mainly in the mitochondria.

• General equation:

  • C6H{12}O6 + 6O2 \rightarrow 6CO2 + 6H2O + \text{ATP}

Stages in Cellular Respiration

1. Glycolysis

2. Pyruvate Oxidation

3. Citric Acid Cycle (Krebs Cycle)

4. Oxidative Phosphorylation

Glycolysis

• Input: Glucose

• Products: 2 ATP, 2 NADH, 2 Pyruvate

Pyruvate Oxidation

• Input: 2 Pyruvate

• Products: 2 Acetyl CoA, 2 CO_2, 2 NADH

Citric Acid Cycle

• Input: 2 Acetyl CoA

• Products: 2 ATP, 6 NADH, 2 FADH, 4 CO_2

Oxidative Phosphorylation

• Involves the electron transport chain and chemiosmosis.

• ATP is synthesized.

Overview of Cellular Respiration

• Glycolysis occurs in the cytosol.

• Pyruvate oxidation and the citric acid cycle occur in the mitochondria.

• Oxidative phosphorylation (electron transport and chemiosmosis) produces approximately 26-28 ATP.