Chapter 18 - Metabolic Pathways and ATP Production

18.1: Metabolism and ATP Energy

• Metabolism comprises all the catabolism and anabolism of cells.
• The catabolic reactions degrade large molecules with accompanying energy release into smaller molecules.
  • In order to synthesize larger, smaller molecules, anabolic reactions require energy.
• The three catabolism stages include food digestion, degradation into smaller groups of large molecules like acetyl and pyruvate, as well as oxidation of acetyl and pyruvate groups in order to release energy for ATP synthesis.
• Catabolic reactions release energy is saved as adenosine
• High-energy hydrolyzed compound triphosphate (ATP),
  • Anabolic reactions require energy.

18.2: Digestion of Foods

• The gastrointestinal process carbons is a Carbons reactions series that collapses
  • Polysaccharides into smaller polysaccharides (dextrins) and finally into glucose monosaccharides, fructose, and galactose.
• The monomers can be absorbed into the bloodstream through the intestinal wall and transferred to cells where new molecules are synthesized with energy and carbon atoms.
• The monoacylglycerol and fatty acids entering the bowels of the small intestines are hydrolyzed.
• New triacylglycerols are formed.
  • They bind to chylomicrons with proteins which carry them through the lymph system and tissue bloodstream.
• Hydrolysis of peptide bonds to produce amino acids which are absorbed and transported to cells through the intestinal wall is used for the digestion of proteins, which begins in the stomach and continues in the intestines.

18.3: Coenzymes in Metabolic Pathways

• Oxidized coenzymes participating in oxidation-reduction reactions are FAD and NAD+.

• When ions and electrons are collected, they are reduced to FADH2 and NADH+H+

• Coenzyme A has a group of thiol usually linked to a group of two-carbon acetyl (acetyl CoA).

  

18.4: Glycolysis: Oxidation of Glucose

• The cytosol glycolysis involves the 10 glucose (6C) to two pyruvate degradation reactions (3C).

  • There are two NADH and two ATPs throughout the reaction series.

• Pyruvate is oxidized to acetyl CoA in mitochondria under aerobic conditions.

  • Pyruvates will be reduced to lactate in the absence of oxygen and NAD+ will be regenerated to further glycolysis.

  

18.5: The Citric Acid Cycle

• In the first reaction sequence known as the citric acid cycle, a group of acetyle and oxaloacetates are combined in order to produce citrate.

  • Citrate is oxidized and decarboxylated to produce 2 CO2, 1 GTP, 3 NADH, and 1 FADH2 with oxaloacetate regeneration.

• ATP results from the direct transfer of phosphate from ADP to GTP.

  

18.6: Electron Transport and Oxidative Phosphorylation

• When their hydrogen ion and electricity are transported to the electron transport system, reduced coenzymes NADH and FADH2 from various metabolic pathways are oxidized into NAD+ and FAD.
  • ATP from ADP and Pi is synthesized with released energy.
• The final admissible, O2, is combined with H2O hydrogen ions and electrons.
  • Hydrogen ions move into the intermembrane, producing an H+ gradient, in the electron transport complexes.
• The energy is released when the H+ ions return to the matrix through ATP Synthase.
• This energy is used in a process called oxidative phosphorylation for driving ATP synthesis.
• NADH oxidization produces ATP 2.5 and ATP 1.5 of FADH2.
  • The total glucose oxidation yields a total of 32 ATP under aerobic conditions.

18.7: Oxidation of Fatty Acids

• Fatty acids are associated with coenzyme A if needed as an energy source and are conveyed to mitochondria, where b-oxidation occurs.
  • Oxidized to produce a shorter, acetyl CoA, and reduced NADH and FADH2 coenzymes, the acyl CoA fatty coA is oxidized.
• Each oxidation cycle produces four ATPs, with another ten ATPs from the Acetyl CoA that enter the cycle, although the energy of a particular fatty acid depends on its length.
  • When high acetyl-CoA levels are present in the cell, ketosis, and acidosis cause ketosis and ketone bodies. are formed.

18.8: Degradation of Amino Acids

• When a quantity of amino acids exceeds the number needed to synthesize nitrogen compounds, they are converted into glutamate by the transamination process.
  • Oxidative glutamate deamination causes ions
• Ammonium ions are converted to urea from oxidative deamination.
• The citric acid cycle or other metabolic tracts may be entered by the carbon atoms caused by amino acid degradation.