Cellular Respiration Overview

Glycolysis

• Glycolysis breaks down glucose into pyruvate
• Enzymes used in glycolysis: Hexokinase, phosphoglucoisomerase, phosphofructokinase, aldolase, triosephosphate isomerase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, pyruvate kinase
• Mnemonic for enzyme order: "H E P UT THE P HONE A ND TRI ED TO G ET THE P LASTIC P LATE TO E AT P IE"
• Net products of glycolysis: 2 ATP, 2 NADH, 2 pyruvate

Transition Reaction

• Pyruvate, a three-carbon molecule, must be oxidized to acetyl-CoA
• Occurs in the mitochondrion under aerobic conditions.
• Converts pyruvate into acetyl-CoA
• Produces CO2 and NADH

Krebs Cycle

• Oxidizes pyruvate molecules to produce energy
• Acetyl-CoA combines with oxaloacetate to form citrate
• Subsequent oxidation produces CO2, NADH, and FADH2
• Electron carriers (NADH and FADH2) enter the electron transport chain

Electron Transport Chain

• Oxidizes NADH and FADH2
• Releases electrons that pump hydrogen ions (H+) from the matrix to the intermembrane space

Chemiosmosis

• H+ passively returns to the matrix via ATP synthase
• This movement powers ATP synthase to produce ATP from ADP and inorganic phosphate

Photosynthesis: Light-Dependent Reactions

• Absorbs radiant energy from the sun via chlorophyll
• Excitation of electrons in photosystem II (PSII) moves them to the reaction center and electron transport complexes
• Electron transport pumps H+ from the stroma to the thylakoid lumen
• H+ movement drives ATP synthesis via ATP synthase
• Plastocyanin transfers low-energy electrons to photosystem I (PSI)
• PSI re-excites electrons via solar energy absorption
• Electrons move to ferredoxin and NADP reductase, reducing NADP+ to NADPH

Photosynthesis: Calvin Cycle

• Utilizes ATP and NADPH from the light-dependent reactions
• Carbon dioxide (CO2) reacts with RuBP (ribulose-1,5-bisphosphate) using RuBisCO
• Produces 3-PGA, which is reduced by ATP and NADPH to form G3P
• G3P used to produce glucose and regenerate RuBP

Cellular Respiration vs Photosynthesis (Similarities)

• Both involve redox reactions and ATP synthesis from electron flow through protein complexes and ADP phosphorylation

This quiz covers the key processes of cellular respiration, including glycolysis, the transition reaction, the Krebs cycle, and the electron transport chain. Learn about the enzymes involved, the products generated, and how these steps contribute to energy production in cells.