Understanding Cellular Respiration: University's Metabolic Processes, Lecture notes of Astronomy

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UNIVERSITY OF PERPETUAL HELP SYSTEM LAGUNA

BIOCHEMISTRY 1

“Cellular Respiration” Matabolic Pathways: Glycolysis, Citric Acid Cycle, and Oxidative Phosphorylation

CELLULAR RESPIRATION

A cellular processes that are characterized by which cells

derive energy from glucose.

Aerobic Respiration

Characterized as a process of cellular respiration that takes

place in the presence of oxygen gas to produce energy.

Anaerobic Respiration

A cellular respiration through which cells can break down

sugars to generate energy in the absence of oxygen.

GLYCOLYSIS: Preparatory Phase

STEP 1: Phosphorylation

Reactant: Glucose

Enzyme: Hexokinase

Product: glucose 6-phosphate

Note: The process of

phosphorylation costs 1 ATP to

produce ADP

STEP 2: Isomerization

Reactant: glucose 6-phosphate

Enzyme: phosphoglucoisomerase

Product: fructose 6-phosphate

STEP 3: Second

Phosphorylation

Reactant: fructose 6-phosphate

Enzyme: phosphofructokinase 1

Product: fructose -1, 6-

bisphosphate

Note: The process of second

phosphorylation costs 1 ATP to

produce ADP

STEP 4: Cleavage

Reactant: fructose 6-phosphate

Enzyme: fructose bisphosphate

aldolase

STEP 5: DHAP into GADP

Reactant: DHAP (dihydroxyacetone phosphate)

Enzyme: triosephosphate isomerase

Product: G3P (glyceraldehyde 3-phosphate)

The preparatory phase spent 2 ATPs to produce 2 ADP

STEP 10: Second Dephosphorylation Reactant: phosphoenolpyruvate Enzyme: pyruvate kinase Product: Pyruvate Note: This process requires ADP to produce 1 ATP GLYCOLYSIS – 10 STEP

• (^) Preparatory phase (first 5 steps)
  • (^) Glucose + 2 ATP = 2 G3P (Glyceraldehyde-3-Phosphate)
• (^) Payoff phase (last 5 steps)
  • (^) 2 G3P = 2 Pyruvate + 2 ATPs Note: Glycolysis byproducts: 2 G3P(Glyceraldehyde-3-Phosphate), 2 Pyruvate, 2 ATPs, and 2 NADH

CITRIC ACID CYCLE

2. Citric Acid Cycle (Kreb’s Cycle)

A cycle of reactions catalyzed by enzymes in which

pyruvate derived from nutrients and converted to Acetyl

Coenzyme A is completely oxidized and broken down into

carbon dioxide and water to produce high-energy

phosphate compounds, which are the source of cellular

energy. It occurs in the Mitochondrion.

STEP 5 : GTP Formation Reactant: Succinyl-CoA Enzyme: succinyl-CoA synthetase Product: succinate Note: This process uses one Phosphate to produce GTP STEP 6 : Oxidation by FAD Reactant: Succinate Enzyme: succinate dehydrogenase Product: fumarate Note: Uses 1 FAD to produce FADH(2) STEP 7 : Hydration Reactant: Fumarate Enzyme: Fumarase Product: Malate Note: In this process 1 water molecule was gained STEP 8 : Final Oxidation Reactant: Malate Enzyme: Malate dehydrogenase Product: oxaloacetate Note: This process uses 1 NAD+ to produce NADH

NOTE: Since the glucose produces 2 pyruvates

during the glycolysis metabolic pathway process,

therefore 2 Acetyl-CoA. The product of the Citric

acid cycle will double as it produces 6 NADH, 2

FADH(2), and 2 ATPs.