Bioenergetics

• Metabolism is the sum of all the chemical reactions that take place in an organism.
• Catabolism is the breakdown of large molecules into smaller ones; energy is generally released during catabolism.
• Anabolism is the synthesis of large molecules from smaller ones; energy is generally absorbed during anabolism.
• •Often, the process is a series of consecutive reactions called a metabolic pathway, which can be linear or cyclic.
• A linear pathway is the series of reactions that generates a final product different from any of the reactants.
• A cyclic pathway is the series of reactions that regenerates the first reaction.
• Energy production occurs in the mitochondria.
• Mitochondria are organelles within the cytoplasm of a cell.
• Mitochondria contain an outer membrane and an inner membrane with many folds.
• The area between the two membranes is called the intermembrane space.
• The area enclosed by the inner membrane is called the matrix, where energy production occurs.
• Name each part:

  A) inner membrane

  B) outer membrane

  C) intermembrane space

  D) matrix

  
• STAGES OF METABOLISM:

  Stage 1: Digestion

  Stage 2: Formation of Acetyl CoA

  Stage 3: The Citric Acid Cycle

  Stage 4: The Electron Transport Chain and Oxidative Phosphorylation
• fill in the blanks:

  A) Acetyl CoA

  B) Citric Acid Cycle

  C) Electron transport chain and oxidative phosphorylation

  
• Hydrolysis with ___ enzyme:

  Carbohydrates: Amylase

  Proteins: Protease pepsin

  Triacylglycerol: Lipase
• Stage 1: DIGESTION

  The catabolism of food begins with digestion, which is catalyzed by enzymes in the saliva, stomach, and small intestines.
• Carbohydrates are hydrolyzed into monosaccharides beginning with amylase enzymes in saliva and continuing in the small intestine.
• Protein digestion begins when stomach acid denatures the protein and pepsin begins to cleave the large protein backbone into smaller peptides.

  • Then, in the small intestines, trypsin and chymotrypsin cleave the peptides into amino acids.
• Triacylglycerols are emulsified by bile secreted by the liver, then hydrolyzed by lipase into 3 fatty acids and a glycerol backbone.
• After Digestion ___ will undergo to form Acetyl CoA.

  Carbohydrates: Glycolysis

  Proteins: Amino acid catabolism

  Triacylglycerol: Fatty acid oxidation
• Stage 2: Formation of Acetyl CoA

  Monosaccharides, amino acids, and fatty acids are degraded into acetyl groups, which are then bonded to coenzyme A forming acetyl-CoA.
• Stage 3: CITRIC ACID CYCLE

  The citric acid cycle is based in the mitochondria, where the acetyl CoA is oxidized to CO2.
• The cycle also produces energy stored as a nucleoside triphosphate and the reduced coenzymes.
• Stage 4: Electron Transport Chain and Oxidative Phosphorylation.

  This happen within the mitochondria and it produces ATP (adenosine 5’-triphosphate).
• ATP is the primary energy-carrying molecule in the body
• Hydrolysis of ATP cleaves 1 phosphate group forming ADP and hydrogen phosphate (HPO4^2-) releasing 7.3 kcal/mol of energy.
• Phosphorylation is the reverse reaction, where phosphate group is added to ADP. It reforms ATP and requires 7.3 kcal/mol of energy.
• Any process (walking, running, breathing) is fueled by the release of energy when ATP is hydrolyzed to ADP.
• Energy is absorbed and stored in ATP when it is synthesized from ADP.
• Is energy released or absorbed?

  A) released

  
• Is the energy released or absorbed?

  A) absorbed

  
• Coupled reactions are pairs of reactions that occur together.
• The energy released by one reaction is absorbed by the other reaction.
• Coupling an energetically unfavorable (needs a pair) reaction with a favorable one that releases more energy than the amount required is common in biological reactions.
• The hydrolysis of ATP provides the energy for the phosphorylation of glucose. This is a pair of reaction where one releases energy to be used by the other.
• In this example, ATP -> ADP released an energy which was then used by glucose to produce the product glucose 6-phosphate.

  
• A coenzyme (reagent) acting as an oxidizing agent causes an oxidation reaction to occur, so the coenzyme is reduced. Through re-dox reaction.
• When a coenzyme acts as an oxidizing agent, it gains H+ and e−.
• A coenzyme acting as a reducing agent causes a reduction reaction to occur, so the coenzyme is oxidized.
• When a coenzyme acts as a reducing agent, it loses H+ and e−.