Biochemical Energy Production

• Metabolism


  The sum total of all the biochemical reactions that take place in a living organism
• Catabolism


  All metabolic reactions in which large biochemical molecules are broken down to smaller ones
• Anabolism


  All metabolic reactions in which small biochemical molecules are joined together to form larger ones
• Metabolic pathways


  • May be linear, in which a series of reactions generates a final product
  • May be cyclic, in which a series of reactions regenerates the first reactant
• The major metabolic pathways for all life forms are similar
• Prokaryotic cells


  Cells that have no nucleus and are found only in bacteria
• Eukaryotic cells


  Cells in which the DNA is found in a membrane-enclosed nucleus, found in all higher organisms
• Key components of a eukaryotic cell

  • Plasma membrane
  • Nucleus
  • Cytosol
  • Ribosomes
  • Lysosomes
  • Mitochondria
• Cytoplasm


  The water-based material of a eukaryotic cell that lies between the nucleus and the outer membrane
• Organelle


  A minute structure within the cytoplasm of a cell that carries out a specific cellular function
• Cytosol


  The water-based fluid part of the cytoplasm of a cell
• Ribosome


  The site where protein synthesis occurs
• Lysosome


  An organelle that contains hydrolytic enzymes needed for cellular rebuilding, repair, and degradation
• Mitochondrion


  An organelle responsible for the generation of most of the energy for a cell
• Mitochondrion


  • Contains an outer membrane and a multifolded inner membrane
  • The inner membrane divides the mitochondrion into two separate compartments: the matrix and the intermembrane space
  • The folds of the inner membrane that protrude into the matrix are called cristae
  • Contains ATP synthase complexes on the matrix side of the inner membrane that are responsible for ATP synthesis
• Adenosine monophosphate (AMP)


  One of the nucleotides present in RNA molecules
• Adenosine diphosphate (ADP)


  Differs structurally from AMP only in the number of phosphate groups present
• Adenosine triphosphate (ATP)


  Differs structurally from AMP and ADP in the number of phosphate groups present
• Phosphoester bond


  The bond between a phosphate group and a ribose group
• Phosphoanhydride bond


  The chemical bond formed when two phosphate groups react with each other and a water molecule is produced
• Phosphoryl group


  The functional group derived from a phosphate ion when the latter becomes part of another molecule
• Hydrolysis of ATP and ADP

  1. ATP + H2O → ADP + Pi + energy

  2. ADP + H2O → AMP + Pi + energy
• The phosphoanhydride bonds in ATP and ADP are very reactive bonds that require less energy than normal to break
• Phosphoanhydride bonds


  Very reactive bonds that require less energy than normal to break
• Bond strain


  Greater-than-normal electron-electron repulsive forces at specific locations within a molecule, causing the increased reactivity of phosphoanhydride bonds in ATP and ADP
• Hydrolysis of phosphoanhydride bonds in ATP and ADP


  Energy-producing reactions that are used to drive cellular processes requiring energy input
• Adenosine monophosphate (AMP)


  Nucleotide containing adenine, ribose, and one phosphate group
• Adenosine diphosphate (ADP)


  Nucleotide containing adenine, ribose, and two phosphate groups
• Adenosine triphosphate (ATP)


  Nucleotide containing adenine, ribose, and three phosphate groups
• ATP is the most prevalent nucleotide triphosphate present in cells
• Other nucleotide triphosphates present in cells include UTP, GTP, and CTP
• Flavin adenine dinucleotide (FAD)


  Coenzyme required in numerous metabolic redox reactions, containing flavin, ribitol, and ADP subunits
• Oxidation


  Involves hydrogen atom loss
• Reduction


  Involves hydrogen atom gain
• Reduction of FAD to FADH2

  FAD + 2H + 2e → FADH2
• Nicotinamide adenine dinucleotide (NAD)


  Coenzyme involved in metabolic redox reactions, containing nicotinamide, ribose, and ADP subunits
• Reduction of NAD to NADH

  NAD + 2H + 2e → NADH + H+
• Coenzyme A (CoA-SH)


  Coenzyme involved in the transfer of acetyl groups, containing 2-aminoethanethiol, pantothenic acid, and phosphorylated ADP subunits
• Acetyl group


  The portion of an acetic acid molecule (CH3-COOH) that remains after the -OH group is removed from the carboxyl carbon atom
• Formation of acetyl CoA

  Acetyl group bonds to CoA-SH through a thioester bond